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disturbances associated with physical symptoms and usage of computers
International Journal of Industrial Ergonomics 43 (2013) 257e263
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International Journal of Industrial Ergonomics journal homepage: www.elsevier.com/locate/ergon
Self-reported sleep disorders/disturbances associated with physical symptoms and usage of computers Leena Korpinen a, b, *, Rauno Pääkkönen c a
Environmental Health, Tampere University of Technology, Tampere, Finland School of Medicine, University of Tampere, Tampere, Finland c Finnish Institute of Occupational Health, Tampere, Finland b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 8 November 2011 Received in revised form 29 December 2012 Accepted 7 May 2013 Available online 13 June 2013
The aim of our work is to study self-reported sleep disorders/disturbances associated with physical symptoms and usage of computers, and to analyse physical symptoms of different groups, usage of desktop computers, usage of portable computers or mini-computers, and background information. The study was carried out as a cross-sectional study by posting a questionnaire to 15 000 working-age persons. The responses (6121) included 1016 (16.6%) respondents, who reported that they suffered quite often or more often sleeping disorders/disturbances during the last 12 months. Of those respondents 708 (69.7%) were employed. In statistical analyses comparisons have been done between: 1) workers with quite often or more often sleep disorders/disturbances and without and 2) employed and unemployed persons with quite often or more often sleep disorders/disturbances. When comparing employed persons with and without sleep disorders/disturbances we found significant differences in self-reported physical symptoms and mental symptoms. In addition, there were differences in the usage of desktop computers at leisure. In the future it is important to take into account that persons with sleep disorders also have other differences e.g., in symptoms as persons without sleep disorders. Situations can also be quite different if a person is in employed or unemployed. Relevance to industry: Sleep disorders/disturbances are quite common symptoms that have their effect on the productivity and well-being of industrial workers. A large-scale questionnaire offers a good reference for evaluating the prevalence of the self-reported sleep disorders/disturbances associated with physical symptoms and usage of computers. Ó 2013 Elsevier B.V. All rights reserved.
Keywords: Sleep disorders Sleep disturbances Symptoms Questionnaire Computer
1. Introduction Sleep disorders/disturbances disturbances, such as chronic insomnia, are common problems in populations of Western industrialised countries (Koskenvuo et al., 2010). For example according Buscemi et al. (2005) and Ohayon and Partinen (2002) 10e 35% of persons suffer from insomnia symptoms. Sleep disorders/ disturbances have been shown to be associated with many health risks and medical conditions (Buscemi et al. , 2005); Healey et al., 1981; Vahtera et al., 2007). Swanson et al. (2011) studied how sleep impacts work performance and how work affects sleep in individuals not at-risk for a sleep disorder and assessed work performance outcomes for
* Corresponding author. ELT, Environmental Health, Tampere University of Technology, P.O. Box 589, 33101 Tampere, Finland. Fax: þ358 3 3115 3751. E-mail address: leena.korpinen@tut.fi (L. Korpinen). 0169-8141/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ergon.2013.05.004
individuals at-risk for sleep disorders. Their study included insomnia, obstructive sleep apnea (OSA) and restless legs syndrome (RLS). In addition they characterized work performance impairments in shift workers (SW) at-risk for shift work sleep disorders relative to SW and day workers. Based on the answers of the 1000 Americans, who worked 30 h or more per week, they classified 37% of respondents as at-risk for any sleep disorder. They found that presenteeism was a significant problem for individuals with insomnia symptoms, OSA and RLS when they compared results with respondents not at-risk. In addition other research groups fould that reduced productivity and absenteeism are the most widely work performance impairments in individuals with insomnia (Daley et al., 2008; Erman et al., 2008; Godet-Cayre et al., 2006; Kleinman et al., 2009; Leger et al., 2002, 2006; Ozminkowski et al., 2007; Walsh et al., 2007). Leger et al. (2002) also reported that occupational accidents were more common among French employees characterized as experiencing severe insomnia as compared with matched good sleepers.
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Sleep complaints are connected to cardiovascular disease (Schwartz et al., 1999; Wolk et al., 2005). In some publications the hypothesis that the chronic insomnia is an independent risk factor for cardiovascular disease has been tested and some positive findings have reported (Mallon et al., 2002; Nilsson et al., 2001; Schwartz et al., 1998). Spiegelhalder et al. (2011) investigated also the association between primary insomnia, defined as subjectively reported sleep disturbance in the absence of any other pathology or substance intake, and alterations in polysomnographically determined nocturnal heart rate (HR) and heart rate variability (HRV). They evaluated 104 participants (58 with primary insomnia, 46 healthy controls). They summarized that a lower wake-to-sleep HR reduction as well as a lower standard deviation of RR intervals (SDNN) were found in subjectively reported insomnia, while resting HR and frequency domain measures of HRV were normal. They also found that a reduced parasympathetic activity compared to healthy controls. Urponen et al. (1988) studied self-evaluations of factors promoting and disturbing sleep in Finland. Their aim was to describe the factors which middle-aged urban people in Finland perceived as promoting or disturbing sleep. They showed that the quality of sleep is determined by numerous factors such as social and psychological factors, health status, external sleeping conditions, lifestyle and living habits. For men the most important factor which disturbed falling asleep or quality of sleep was work-related pressure and fatigue (20%) and in the women’s ranking work problems appeared third (Urponen et al., 1988). Ohayon and Sagales (2010) reported that in Spain 20.8% of those sample reported at least one insomnia symptom occurred at least three nights per week. The prevalence in women was 23.9% and in men 17.6% and it increased with age. In addition, other research groups found that sleep complaints tend to be more prevalent among women and older people, the widowed and divorced, and among those in lower socioeconomic positions (Arber et al., 2009; Ribet and Derriennic, 1999; Roth and Roehrs, 2003; Sekine et al., 2006). Lallukka et al. (2010) studied how physical working conditions, psychosocial working conditions and workefamily conflicts are associated with sleep complaints, and whether health behaviours explain these associations. They used questionnaire surveys collected in 2001e2002 among 40e60-year-old employees of the City of Helsinki in Finland. They found that physically strenuous working conditions, psychosocial job strain and workefamily conflicts can increase sleep complaints (Lallukka et al., 2010). In another Finnish study (Perkiö-Mäkelä et al., 2006), 3122 persons (51% male and 49% female) ages 25e64 were interviewed by phone. The interviewed group was the same as Finnish workaged population in general; 70% employed and 8% unemployed. According to the interviews: 48% of the participants had pain in the neckeshoulder, 32% had pain in the arms and shoulder, 28% had hip and lower back pain, 28% had weakness, 25% had insomnia, 24% had pain in the hips and legs, 23% had tension and nervousness, 22% had irritation, 19% had pain in the wrists and fingers and 13% had depression (Perkiö-Mäkelä et al., 2006). The link between the symptoms and sleep disorders was not studied in this study. The use of new and different technical equipment has increased in many jobs. According to the ‘Fourth European Working Condition Survey’ Report (Parent-Thirion et al., 2007) around 26% of workers work with a computer all, or almost all, of the time. In 1990, the equivalent figure was around 13% (Parent-Thirion et al., 2007). Thomée et al. (2010) studied with qualitative methods perceived connections between information and communication technology use and mental symptoms (also sleep disorders) among young adults. They interviewed 16 women and 16 men (ages 21e28 years). They discovered that central factors which appeared to explain high quantitative ICT use were: personal dependency,
demands for achievement, availability originating from the domains of work (study, social life, and individual aspirations). The aim of our work is to study self-reported sleep disorders/ disturbances associated with physical symptoms and usage of computers comparing: 1) workers with quite often or more often sleep disorders/disturbances and without, and 2) employed and unemployed persons with quite often or more often sleep disorders/disturbances. The aim is to analyse groups of physical symptoms, usage of desktop computers, usage of portable computers or mini-computers, and background information such as age and gender. Our work is part of a larger questionnaire study on the possible influence of new technical equipment on the health of the workingage population. The results of physical and psychological symptoms have been reported earlier (Korpinen et al., 2009; Korpinen and Pääkkönen, 2009). 2. Methods 2.1. Study population and questionnaire The questionnaire was sent to 15 000 Finns in 2002. The study focused on the working age population. Therefore, the questionnaire was only sent to people between the ages of 18e65. Names and addresses were obtained as a random sample from the Finnish Population Register Centre. The study design was approved by the Ethical Committee (Pirkanmaa Health District, Finland, decision R02099). The questionnaire included six sections: 1) background information (such as age, gender, marital status, education, occupation, and home county), 2) the familiarity and use of given technical devices at leisure and at work, 3) physical loading and ergonomics, 4) psychological welfare 5) accidents and close call situations at leisure or at work and 6) an open-ended question ‘other observations concerning technology and health’. The details of the questionnaire have been reported in an earlier article (Korpinen et al., 2009). 2.2. Statistical analysis First, only the respondents, who had quite often or more often sleep disorders/disturbances were chosen. In addition, using the data, subgroups were made based on gender and work situations (employed and unemployed persons). The statistical analyses were done using the IBM SPSS Statistics version 19. The options for question ‘13) Have you had an ache, pain or numbness in the following body part during the last twelve months? a) in wrists and fingers, b) in elbows and forearms, c) in neck, d) in shoulders, e) in hip and lower back, f) in feet‘ was classified so that answers: ‘cannot say’,’ not at all’ and ‘sometimes’ were coded 0 (no symptoms), quite often was 1, often was 2, and very often was 3. In addition, the question ‘16) Have you suffered a) sleeping disorders/disturbances, b) depression, c) exhaustion at work, d) substance addiction, e) anxiety or f) fear situations during the last 12 months?’ were codified in the same way. In the first analysis background information (age, gender, marital status, education and occupation), daily usage of computers at work (questions 11b and 11e) and symptom questions 13aef and 16aef were analysed with independent samples ManneWhitney U-test. In analyses of employed and unemployed persons we compared groups: 1) respondents, who had quite often or more often sleeping disorders/disturbances and 2) respondents, had not quite often or more often sleeping disorders/disturbances. The same analyses were also made for subgroups of women and men. In the second analysis of independent samples ManneWhitney U-test we used the same questions (background information, usage
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of computers at work and symptoms) as in first analysis and compared groups: 1) employed respondents who had quite often or more often sleeping disorders/disturbances and 2) unemployed respondents, who had quite often or more often sleeping disorders/ disturbances. The same analyses were also made for subgroups of women and men. In this study p-value 0.05 was chosen. 3. Results 3.1. Background information A total of 6121 responses arrived (during 2002e2003) and the response percent was 41. The mean age standard deviation was 41.3 13.1 years. For all respondents 4368 (71.4%) persons were at work and 1599 (26.1%) were unemployed persons. In addition 2.5% of responses were missing. Table 1 shows background information and the results of all employed persons, workers with sleeping disorders/disturbances, female workers with sleeping disorders/ disturbances and male workers with sleeping disorders/disturbances. In the question 11b usage of a desktop computer at work and 11e usage of a portable computer or mini-computer at work, there are the amounts of ‘daily’ answers. In the part on the question 13aef and in the part on the question 16aef Table 1 shows the amount of answers ‘quite often’, ‘often’ and ‘very often’.
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All of 1016 (16.6%) respondents reported that they suffered quite often or more often sleeping disorders/disturbances during the last 12 months. Of those 708 (69.7%) were employed and 276 (27.2%) were unemployed (3.1% missing). From unemployed persons with quite often or more often sleeping disorders/disturbances 48 (17.4%) used a daily desktop computer at leisure and 3 (1.1%) used daily portable computers or mini-computers at leisure. From the employed respondents 241 (34.0%) used daily desktop computer at leisure and 42 (5.9%) used daily portable computers or minicomputers at leisure. 3.2. Results of an independent sample ManneWhitney U-test Table 2 shows the analyses of the background information, questions 13aef (physical symptoms) and 16bef (mental symptoms) in comparison groups: all workers with and without sleeping disorders/disturbances, female workers with and without sleeping disorders/disturbances and male workers with and without sleeping disorders/disturbances. In analyses of all workers with and without sleeping disorders/disturbances there were significant differences in age, in gender, in usage of desktop computer at leisure, and in all symptoms. In the women’s and men’s data the significant differences were in age and in all symptoms. In addition in the men’s data (Table 2) there is difference in marital status.
Table 1 A summary of background information from all employed persons, employed persons with sleep disorders/disturbances, female and male employed persons with sleep disorders/disturbances, the daily usage of the computers at work, mental symptoms and experienced pain, numbness or aches (amounts of positive answers including answers; ‘quite often’, ‘often’, ‘very often’). Topics of questions and choices
Q3 Marital status Single Married or live-in Divorced Widow or widower Q5 Education Comprehensive school Matriculation Vocational school Vocational high school University Q6 Occupation Enterpriser Farmer Upper-level white-collar workersa Lower-level white-collar workersb Blue-collar workersc Home work, student Other Q11 Use at work (daily) b) Desktop computer e) Portable computer or mini-computer Q13 Experienced pain, numbness or aches a) In wrists or fingers b) In elbows or forearms c) In neck d) In shoulders e) In hip and lower back f) In feet Q16 Mental symptoms a) Sleeping disorders/disturbances b) Depression c) Exhaustion at work d) Substance addiction e) Anxiety f) Fear situations a b c
All employed persons
%
Workers with sleeping disorders/ disturbances
%
Female workers with sleeping disorders/ disturbances
%
Men workers with sleeping disorders/ disturbances
%
768 3218 328 48
17.6 73.8 7.5 1.1
129 489 80 9
18.2 69.2 11.3 1.3
90 290 58 6
20.3 65.3 13.1 1.4
39 197 22 3
14.9 75.5 8.4 1.1
586 349 1208 1534 679
13.5 8.0 27.7 35.2 15.6
96 61 171 259 118
13.6 8.7 24.3 36.7 16.7
62 39 91 181 71
14.0 8.8 20.5 40.8 16.0
34 22 79 77 47
13.1 8.5 30.5 29.7 18.1
366 105 971 1150 1548 48 171
8.4 2.4 22.3 26.4 35.5 1.1 3.9
59 12 171 228 203 11 22
8.4 1.7 24.2 32.3 28.8 1.6 3.1
27 8 89 172 128 8 11
6.1 1.8 20.1 38.8 28.9 1.8 2.5
32 4 82 55 75 3 10
12.3 1.5 31.4 21.1 28.7 1.1 3.8
2728 426
62.5 9.8
468 73
66.1 10.3
300 25
67.4 5.6
167 48
64.0 18.4
855 607 2194 1338 1396 991
19.6 13.9 50.2 30.6 31.9 22.7
246 181 513 354 351 277
34.8 25.5 72.4 50.0 49.5 39.1
178 131 355 248 229 173
40.1 29.4 79.8 55.7 51.5 38.9
67 49 156 105 122 104
25.7 18.8 59.8 40.3 46.7 39.9
708 350 853 68 242 108
16.2 8.0 19.4 1.6 5.5 2.4
225 391 37 150 74
31.8 55.2 5.2 21.2 10.5
148 239 16 101 51
33.3 53.7 3.6 22.7 11.5
77 152 21 49 23
29.5 58.2 8.0 18.8 8.8
Administrative or managerial duties, designing, research, teaching. Clerical duties and supervision. Industrial workers, distributive and service trade.
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Table 2 Comparison between workers with and without sleep disorders/disturbances, female workers with and without sleep disorders/disturbances and male workers with and without sleep disorders/disturbances, (with independent samples ManneWhitney U-test analyses) for backgroud information, daily usage of computers, physical and mental symptoms (amounts of positive answers to symptoms including answers; ‘quite often’, ‘often’, ‘very often’). Comparison groups with ManneWhitney U-test
Workers with and without sleeping disorders/disturbances Asymp. Sig. (2-tailed)
Female workers with and without sleeping disorders/disturbances Asymp. Sig. (2-tailed)
Male workers with and without sleeping disorders/disturbances Asymp.Sig. (2-tailed)
Age Gender Marital status Education Occupation Q11b) Use of desktop computer at work (daily) Q11e) Use of portable computer or mini-computer (daily) Q13 Experienced pain, numbness or aches a) In wrists or fingers b) In elbows or forearms c) In neck d) In shoulders e) In hip and lower back f) In feet Q16 Mental symptoms b) Depression c) Exhaustion at work d) Substance addiction e) Anxiety f) Fear situations
<0.001** <0.001** 0.085 0.311 0.010** 0.029**
<0.001** e 0.725 0.959 0.051 0.213
<0.001** e 0.030** 0.271 0.031** 0.115
0.585
0.579
0.176
<0.001** <0.001** <0.001** <0.001** <0.001** <0.001**
<0.001** <0.001** <0.001** <0.001** <0.001** <0.001**
<0.001** 0.001** <0.001** <0.001** <0.001** <0.001**
<0.001** <0.001** <0.001** <0.001** <0.001**
<0.001** <0.001** 0.001** <0.001** <0.001**
<0.001** <0.001** <0.001** <0.001** <0.001**
**Significant at p < 0.05.
Table 3 shows the results of a comparison between all employed and unemployed persons, female employed and unemployed persons and male employed and unemployed persons with sleeping disorders/disturbances. In the analysis of all employed and unemployed persons with sleeping disorders/disturbances there were significant differences in education, in occupation, in usage of desktop computer at leisure, in usage of portable computer or minicomputer at leisure, in some physical symptoms Q13e-f and in all mental symptoms. In the women’s data (Table 3) there are no significant differences in substance addiction, and in men’s data
there are not differences in depression and in fear situations. In addition, in the men’s data (Table 3) there are differences in marital status. 4. Discussion 4.1. Evaluation of methods In this study the population was 15 000 Finns and the amount of responses were 6121 (41%), which is quite large. Therefore, it was
Table 3 Comparison between employed and unemployed persons with sleep disorders/disturbances, female employed and unemployed persons with sleep disorders/disturbances, and male employed and unemployed persons with sleep disorders/disturbances, (with independent samples ManneWhitney U-test analyses) for backgroud information, daily usage of computers, physical and mental symptoms (amounts of positive answers to symptoms including answers; ‘quite often’, ‘often’, ‘very often’). Comparison groups with ManneWhitney U-test
Employed and unemployed persons with sleeping disorders/ disturbances Asymp. Sig. (2-tailed)
Age Gender Marital status Education Occupation Q8b) Use of desktop computer at leisure (daily) Q8e) Use of portable computer or minicomputer at leisure (daily) Q13 Experienced pain, numbness or aches a) In wrists or fingers b) In elbows or forearms c) In neck d) In shoulders e) In hip and lower back f) In feet Q16 Mental symptoms b) Depression c) Exhaustion at work d) Substance addiction e) Anxiety f) Fear situations
0.629 0.913 0.008** <0.001** <0.001** <0.001** 0.001**
e
e
0.351 <0.001** <0.001** <0.001** 0.077
0.001** <0.001** <0.001** 0.001** 0.005**
0.591 0.801 0.543 0.895 <0.001** <0.001**
0.527 0.633 0.091 0.545 0.008** <0.001**
0.058 0.223 0.170 0.265 0.010** 0.003**
0.016** <0.001** 0.014** 0.001** 0.007**
0.071 <0.001** 0.546 0.011** 0.015**
0.118 <0.001** 0.006** 0.018** 0.230
**Significant at p < 0.05.
Employed and unemployed women with sleeping disorders/ disturbances Asymp. Sig. (2-tailed)
Employed and unemployed men with sleeping disorders/ disturbances Asymp. Sig. (2-tailed)
0.335
0.049**
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possible to make analyses on the subgroup of persons, who reported quite often or more often sleep disorders/disturbances. In addition in our earlier article (Korpinen and Pääkkönen, 2009) we reported, that in this Finnish working-age population 59% had some or more sleeping disorders/disturbances and sleep disorders/ disturbances were associated with the use of a desktop computer in all data and in the women’s data. Because so many respondents have the sleep disorders/disturbances symptoms and the sleep disorders/disturbances had associations, it was interesting to make more analyses from this topic. However, one of the difficulties with this study is that it is basing sleep disorders on one question in a larger survey. There is no clarity as to the type of sleep disorders occurring. This is one weakness of this study. In this article, we used cases, which had quite often or more often sleep disorders/disturbances. From our data it is not possible to say exactly what sleep disorders respondents had and how difficult it is. It is also important to take into account the analyses of results that our data included only selfreported symptoms. It is not same as sleep disorder diagnosis. Our data is quite old, because we collected it in 2002e2003. For example respondents’ usage of different devices can be nowadays different than what it was when they answered the questionnaire. However, physical symptoms and mental symptoms are perhaps more permanent parameters than the usage of computers or mobile phones. Therefore our results are still relevant. Different types of biases were also included in the study. The questionnaire or questions can influence participants and only the active persons participated in the questionnaire. Because the questionnaire included only one question regarding the sleep disorders/disturbances it is possible that persons who are interested in sleep disorders did not answer. In addition respondents’ opinions can change quite quickly as the technology develops. Not everyone understands the physical or mental symptoms in the same way and the questionnaire did not include all possible questions or symptoms. There can be other factors, which can influence the sleep disorders, for example, atmosphere in workplace. 4.2. Evaluation of amount symptoms In our data 16.6% respondents reported that he or she suffered quite often or more often sleeping disorders/disturbances during the last 12 months. Lallukka et al. (2010) reported that in their questionnaire surveys the prevalence of sleep complaints was 24% among women and 20% among men aged 40e60-year-old employees of the City of Helsinki in Finland. According by Buscemi et al. (2005) and Ohayon and Partinen (2002) 10e35% of persons suffer from insomnia symptoms. So our result (16.6%) was quite similar that have been published in this area. In all employed persons’ data, 50.2% of persons had experienced quite often or more pain, numbness or aches in the neck, 30.6% had it in the shoulders and 31.9% in the hip and lower back. In the group of workers with sleep disorders/disturbances 72.4% had experienced quite often or more pain, numbness or aches in the neck, 49.5% in the hip and lower back and 50.0% in the shoulders. Regarding mental symptoms the values are the following: employed persons without sleep disorders/with sleep disorders: depression 8%/31.8%, exhaustion at work 19.4%/55.2%, anxiety 5.5%/ 21.2%, and fear situations 2.4%/10.5%. In other Finnish study (Perkiö-Mäkelä et al., 2006), there was for example: pain in the neckeshoulder 48%, pain in the arms and shoulders 32%, pain in the hip and lower back 28%, weakness 28%, insomnia 25% and pain in the hips and legs 24%. In our data of all employed persons, the values are almost a similar amount as in the other Finnish study (Perkiö-Mäkelä et al., 2006). However, the other study (PerkiöMäkelä et al., 2006) was based on interviews by phone.
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In Ohayon and Sagales (2010) “study prevalence of insomnia and sleep characteristics in the general population of Spain” participants with insomnia symptoms were more frequently treated for a physical disease. In addition, in other epidemiological studies, where participants with insomnia were more likely to report poor health and various diseases for example asthma, chronic bronchitis, rheumatic disease, non treated hypertension, heart diseases or painful physical affliction (Gislason and Almqvist, 1987; Klink and Quan, 1987; Foley et al., 1995; Ohayon et al., 1997a,b; Newman et al., 1997; Schwartz et al., 1999; Andersson et al., 1999). In our data many persons with sleep disorders/disturbances had also other symptoms. 4.3. Comparison between workers with sleep disorders/ disturbances and without sleep disorders/disturbances When comparing all workers with and without sleeping disorders/disturbances there were significant differences in age, gender, daily use of desktop computer at work, and in all symptoms (Table 2). This results supported earlier studies, which found that persons with insomnia were more frequently treated for a physical disease (Gislason and Almqvist, 1987; Klink and Quan, 1987; Foley et al., 1995; Ohayon et al., 1997a,b; Newman et al., 1997; Schwartz et al., 1999; Andersson et al., 1999; Ohayon and Sagales, 2010). In the women’s and men’s data (Table 2), there are almost the same differences as in all employed persons with sleep disorders/disturbances data. Only in the men’s data was there a significant difference in marital status, which is not in the other comparisons. Table 2 shows that there are significant differences in amounts of mental symptoms between persons with and without sleep disorders sleeping disorders/disturbances. However mental health problems can cause sleep disorders. For example Perlman et al. (2006) described that disturbed sleep is a hallmark symptom of depression and Gillin et al. (1996) described that with over 80% of those diagnosed reporting disturbed sleep. Sleep disturbances can also predict depression onset. (Breslau et al., 1997; Chang et al., 1997; Cuijpers et al., 2006; Hatzinger et al., 2004; Lustberg and Reynolds, 2000; Perlis et al., 1997, 2006). 4.4. Comparison between employed and unemployed persons with sleep disorders/disturbances We also studied employed and unemployed persons, who reported that they had quite often or more often sleep disorders/ disturbances. In the all persons comparison (Table 3) there were significant differences in education, in occupation, in usage of computers at leisure, in all mental symptoms, and in some physical symptoms (pain in the hip and lower back and in the feet). It is possible that some respondents were unemployed because they had an ache, pain or numbness in the hip and lower back or in the feet. According to the Finnish statistical office in 2006 over 112 600 Finnish workers received disability pensions based on mental health problems (Official Statistics of Finland, 2009). This can explain the significant differences in our results in mental symptoms between groups of employed and unemployed persons. In addition in our earlier article (Korpinen and Pääkkönen, 2011) we reported that, unemployed middle-aged (45 years old or older) people did not use, e.g., the Internet as much as people in general. This can also influence to results. From Table 3 we can find that women’s (with sleep disorders/ disturbances) and men’s (with sleep disorders/disturbances) results are little different. For example in the women’s data there are no significant differences in substance addiction and in the men’s data there are not differences in depression and in fear situations. Karlqvist et al. (2002) studied also the difference between genders.
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They found that women’s work tasks were more monotonous than men’s. Women also had less breaks and they felt more work stress and musculoskeletal disorders. Pressure due to time constraints caused women to have more symptoms while men had fewer symptoms. It is quite easy to understand that also in our comparison we found few differences in comparison of the women’s groups and in comparison of men’s groups. In the future studies, it is important to take account that there are differences in sleep disorders between female and male employed and unemployed persons. 5. Conclusion In conclusion, it can be stated that 16.2% of Finnish workers suffered quite or more often sleep disorders/disturbances. Of those workers, 72.4% had experienced pain, numbness and aches in the neck, when from all employed persons 50.2% had the same symptoms. When comparing employed persons with and without sleep disorders/disturbances we found significant differences in self-reported physical symptoms and mental symptoms. In addition there were differences in the usage of desktop computer at leisure. When comparing employed and unemployed persons with sleep disorders we found also differences in physical symptoms in the hip and lower back, and in the feet and in some mental symptoms. There were also differences in the usage of computers and in education. In the future, it is important to take account that persons with sleep disorders also have other differences e.g., in symptoms as persons without sleep disorders. In addition, the situation is different if persons are employed or unemployed. Acknowledgements The assistance of the staff (Suuronen, Latva-Teikari and Lehtelä) of Department of Energy and Process Engineering, Environmental Health, Tampere University of Technology is gratefully acknowledged. Special thanks go to Professor Irma Virjo, Faculty of Medicine, Tampere University, for her advice on designing the questionnaire and to M.Sc Maarit Pakarinen, SPSS Finland Oy, for her advice on statistical analyses. References Andersson, H.I., Ejlertsson, G., Leden, I., Schersten, B., 1999. Impact of chronic pain on health care seeking, self care, and medication. Results from a populationbased Swedish study. J. Epidemiol. Commun. Health 53, 503e509. Arber, S., Bote, M., Meadows, R., 2009. Gender and socio-economic patterning of self-reported sleep problems in Britain. Soc. Sci. Med. 68, 281e289. Breslau, N., Roth, T., Rosenthal, L., Andreski, P.S., 1997. Daytime sleepiness: an epidemiological study of young adults. Am. J. Public Health 87, 1649e1653. Buscemi, N., Vandermeer, B., Friesen, C., Bialy, L., Tubman, M., Ospina, M., et al., 2005. Manifestations and management of chronic insomnia in adults. Evid. Rep. Technol. Assess. (Summ) 125, 1e10. Chang, P.P., Ford, D.E., Mead, L.A., Cooper-Patrick, L., Klag, M., 1997. Insomnia in young men and subsequent depression: the Johns Hopkins precursors study. Am. J. Epidemiol. 146, 105e114. Cuijpers, P., Beekman, A., Smit, F., Deeg, D., 2006. Predicting the onset of major depressive disorder and dysthymia in older adults with subthreshold depression: a community based study. Int. J. Geriatr. Psychiatr. 21, 811e818. Daley, M., Morin, C.M., Leblanc, M., Gregoire, J.P., Savard, J., Baillargeon, L., 2008. Insomnia and its relationship to health-care utilization, work absenteeism, productivity and accidents. Sleep Med. 10, 427e438. Erman, M., Guiraud, A., Joish, V., Lerner, D., 2008. Zolpidem extendedrelease 12.5 mg associated with improvements in work performance in a 6-month randomized, placebo-controlled trial. Sleep 31, 1371e1378. Foley, D.J., Monjan, A.A., Brown, S.L., Simonsick, E.M., Wallace, R.B., Blazer, D.G., 1995. Sleep complaints among elderly persons: an epidemiologic study of three communities. Sleep 18, 425e432. Gillin, J.C., Inkwell-Israel, S., Erman, M., 1996. Sleep and sleep wake disorders. In: Tasman, A., Kay, J., Lieberman, J.C. (Eds.), Psychiatry. W.B. Saunders Company, Philadelphia, pp. 1217e1248. Gislason, T., Almqvist, M., 1987. Somatic diseases and sleep complaints: an epidemiological study of 3201 Swedish men. Acta Med. Scand. 221, 475e481.
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Sleep disturbance, psychosocial correlates, and cardiovascular disease in 5201 older adults: the cardiovascular health study. J. Am. Geriatr. Soc. 45, 1e7. Nilsson, P.M., Nilsson, J.A., Hedblad, B., Berglund, G., 2001. Sleep disturbance in association with elevated pulse rate for prediction of mortalitydconsequences of mental strain? J. Intern. Med. 250, 521e529. Official Statistics of Finland, 2009. Statistical Yearbook of Pensioners in Finland. Finnish Centre for Pensions, Social Insurance Institution of Finland. Retrieved May 28, 2009, from: http://www.etk.fi/Binary.aspx?Section¼41194&Item¼61075 (in Finnish). Ohayon, M.M., Caulet, M., Guilleminault, C., 1997a. Complaints about nocturnal sleep: how a general population perceives its sleep, and how this relates to the complaint of insomnia. Sleep 20, 715e723. Ohayon, M.M., Caulet, M., Priest, R.G., Guilleminault, C., 1997b. DSM-IV and ICSD-90 insomnia symptoms and sleep dissatisfaction. Brit. J. Psychiatr. 171, 382e388. 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Disord. 42, 209e212. Perlis, M., Smith, L., Lyness, J., et al., 2006. Insomnia as a risk for onset of depression in the elderly. Behav. Sleep Med. 4, 104e113. Perlman, C.A., Johnson, S.L., Mellman, T.A., 2006. The prospective impact of sleep duration on depression and mania. Bipolar Disord. 8, 271e274. Ribet, C., Derriennic, F., 1999. Age, working conditions, and sleep disorders: a longitudinal analysis in the French cohort E.S.T.E.V. Sleep 22, 491e504. Roth, T., Roehrs, T., 2003. Insomnia: epidemiology, characteristics, and consequences. Clin. Cornerstone 5, 5e15. Schwartz, P.J., Rosenthal, N.E., Wehr, T.A., 1998. Serotonin 1a receptors, melatonin, and the proportional control thermostat in patients with winter depression. Arch. Gen. Psychiatr. 55, 897e903.
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Contents lists available at SciVerse ScienceDirect
International Journal of Industrial Ergonomics journal homepage: www.elsevier.com/locate/ergon
Self-reported sleep disorders/disturbances associated with physical symptoms and usage of computers Leena Korpinen a, b, *, Rauno Pääkkönen c a
Environmental Health, Tampere University of Technology, Tampere, Finland School of Medicine, University of Tampere, Tampere, Finland c Finnish Institute of Occupational Health, Tampere, Finland b
a r t i c l e i n f o
a b s t r a c t
Article history: Received 8 November 2011 Received in revised form 29 December 2012 Accepted 7 May 2013 Available online 13 June 2013
The aim of our work is to study self-reported sleep disorders/disturbances associated with physical symptoms and usage of computers, and to analyse physical symptoms of different groups, usage of desktop computers, usage of portable computers or mini-computers, and background information. The study was carried out as a cross-sectional study by posting a questionnaire to 15 000 working-age persons. The responses (6121) included 1016 (16.6%) respondents, who reported that they suffered quite often or more often sleeping disorders/disturbances during the last 12 months. Of those respondents 708 (69.7%) were employed. In statistical analyses comparisons have been done between: 1) workers with quite often or more often sleep disorders/disturbances and without and 2) employed and unemployed persons with quite often or more often sleep disorders/disturbances. When comparing employed persons with and without sleep disorders/disturbances we found significant differences in self-reported physical symptoms and mental symptoms. In addition, there were differences in the usage of desktop computers at leisure. In the future it is important to take into account that persons with sleep disorders also have other differences e.g., in symptoms as persons without sleep disorders. Situations can also be quite different if a person is in employed or unemployed. Relevance to industry: Sleep disorders/disturbances are quite common symptoms that have their effect on the productivity and well-being of industrial workers. A large-scale questionnaire offers a good reference for evaluating the prevalence of the self-reported sleep disorders/disturbances associated with physical symptoms and usage of computers. Ó 2013 Elsevier B.V. All rights reserved.
Keywords: Sleep disorders Sleep disturbances Symptoms Questionnaire Computer
1. Introduction Sleep disorders/disturbances disturbances, such as chronic insomnia, are common problems in populations of Western industrialised countries (Koskenvuo et al., 2010). For example according Buscemi et al. (2005) and Ohayon and Partinen (2002) 10e 35% of persons suffer from insomnia symptoms. Sleep disorders/ disturbances have been shown to be associated with many health risks and medical conditions (Buscemi et al. , 2005); Healey et al., 1981; Vahtera et al., 2007). Swanson et al. (2011) studied how sleep impacts work performance and how work affects sleep in individuals not at-risk for a sleep disorder and assessed work performance outcomes for
* Corresponding author. ELT, Environmental Health, Tampere University of Technology, P.O. Box 589, 33101 Tampere, Finland. Fax: þ358 3 3115 3751. E-mail address: leena.korpinen@tut.fi (L. Korpinen). 0169-8141/$ e see front matter Ó 2013 Elsevier B.V. All rights reserved. http://dx.doi.org/10.1016/j.ergon.2013.05.004
individuals at-risk for sleep disorders. Their study included insomnia, obstructive sleep apnea (OSA) and restless legs syndrome (RLS). In addition they characterized work performance impairments in shift workers (SW) at-risk for shift work sleep disorders relative to SW and day workers. Based on the answers of the 1000 Americans, who worked 30 h or more per week, they classified 37% of respondents as at-risk for any sleep disorder. They found that presenteeism was a significant problem for individuals with insomnia symptoms, OSA and RLS when they compared results with respondents not at-risk. In addition other research groups fould that reduced productivity and absenteeism are the most widely work performance impairments in individuals with insomnia (Daley et al., 2008; Erman et al., 2008; Godet-Cayre et al., 2006; Kleinman et al., 2009; Leger et al., 2002, 2006; Ozminkowski et al., 2007; Walsh et al., 2007). Leger et al. (2002) also reported that occupational accidents were more common among French employees characterized as experiencing severe insomnia as compared with matched good sleepers.
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Sleep complaints are connected to cardiovascular disease (Schwartz et al., 1999; Wolk et al., 2005). In some publications the hypothesis that the chronic insomnia is an independent risk factor for cardiovascular disease has been tested and some positive findings have reported (Mallon et al., 2002; Nilsson et al., 2001; Schwartz et al., 1998). Spiegelhalder et al. (2011) investigated also the association between primary insomnia, defined as subjectively reported sleep disturbance in the absence of any other pathology or substance intake, and alterations in polysomnographically determined nocturnal heart rate (HR) and heart rate variability (HRV). They evaluated 104 participants (58 with primary insomnia, 46 healthy controls). They summarized that a lower wake-to-sleep HR reduction as well as a lower standard deviation of RR intervals (SDNN) were found in subjectively reported insomnia, while resting HR and frequency domain measures of HRV were normal. They also found that a reduced parasympathetic activity compared to healthy controls. Urponen et al. (1988) studied self-evaluations of factors promoting and disturbing sleep in Finland. Their aim was to describe the factors which middle-aged urban people in Finland perceived as promoting or disturbing sleep. They showed that the quality of sleep is determined by numerous factors such as social and psychological factors, health status, external sleeping conditions, lifestyle and living habits. For men the most important factor which disturbed falling asleep or quality of sleep was work-related pressure and fatigue (20%) and in the women’s ranking work problems appeared third (Urponen et al., 1988). Ohayon and Sagales (2010) reported that in Spain 20.8% of those sample reported at least one insomnia symptom occurred at least three nights per week. The prevalence in women was 23.9% and in men 17.6% and it increased with age. In addition, other research groups found that sleep complaints tend to be more prevalent among women and older people, the widowed and divorced, and among those in lower socioeconomic positions (Arber et al., 2009; Ribet and Derriennic, 1999; Roth and Roehrs, 2003; Sekine et al., 2006). Lallukka et al. (2010) studied how physical working conditions, psychosocial working conditions and workefamily conflicts are associated with sleep complaints, and whether health behaviours explain these associations. They used questionnaire surveys collected in 2001e2002 among 40e60-year-old employees of the City of Helsinki in Finland. They found that physically strenuous working conditions, psychosocial job strain and workefamily conflicts can increase sleep complaints (Lallukka et al., 2010). In another Finnish study (Perkiö-Mäkelä et al., 2006), 3122 persons (51% male and 49% female) ages 25e64 were interviewed by phone. The interviewed group was the same as Finnish workaged population in general; 70% employed and 8% unemployed. According to the interviews: 48% of the participants had pain in the neckeshoulder, 32% had pain in the arms and shoulder, 28% had hip and lower back pain, 28% had weakness, 25% had insomnia, 24% had pain in the hips and legs, 23% had tension and nervousness, 22% had irritation, 19% had pain in the wrists and fingers and 13% had depression (Perkiö-Mäkelä et al., 2006). The link between the symptoms and sleep disorders was not studied in this study. The use of new and different technical equipment has increased in many jobs. According to the ‘Fourth European Working Condition Survey’ Report (Parent-Thirion et al., 2007) around 26% of workers work with a computer all, or almost all, of the time. In 1990, the equivalent figure was around 13% (Parent-Thirion et al., 2007). Thomée et al. (2010) studied with qualitative methods perceived connections between information and communication technology use and mental symptoms (also sleep disorders) among young adults. They interviewed 16 women and 16 men (ages 21e28 years). They discovered that central factors which appeared to explain high quantitative ICT use were: personal dependency,
demands for achievement, availability originating from the domains of work (study, social life, and individual aspirations). The aim of our work is to study self-reported sleep disorders/ disturbances associated with physical symptoms and usage of computers comparing: 1) workers with quite often or more often sleep disorders/disturbances and without, and 2) employed and unemployed persons with quite often or more often sleep disorders/disturbances. The aim is to analyse groups of physical symptoms, usage of desktop computers, usage of portable computers or mini-computers, and background information such as age and gender. Our work is part of a larger questionnaire study on the possible influence of new technical equipment on the health of the workingage population. The results of physical and psychological symptoms have been reported earlier (Korpinen et al., 2009; Korpinen and Pääkkönen, 2009). 2. Methods 2.1. Study population and questionnaire The questionnaire was sent to 15 000 Finns in 2002. The study focused on the working age population. Therefore, the questionnaire was only sent to people between the ages of 18e65. Names and addresses were obtained as a random sample from the Finnish Population Register Centre. The study design was approved by the Ethical Committee (Pirkanmaa Health District, Finland, decision R02099). The questionnaire included six sections: 1) background information (such as age, gender, marital status, education, occupation, and home county), 2) the familiarity and use of given technical devices at leisure and at work, 3) physical loading and ergonomics, 4) psychological welfare 5) accidents and close call situations at leisure or at work and 6) an open-ended question ‘other observations concerning technology and health’. The details of the questionnaire have been reported in an earlier article (Korpinen et al., 2009). 2.2. Statistical analysis First, only the respondents, who had quite often or more often sleep disorders/disturbances were chosen. In addition, using the data, subgroups were made based on gender and work situations (employed and unemployed persons). The statistical analyses were done using the IBM SPSS Statistics version 19. The options for question ‘13) Have you had an ache, pain or numbness in the following body part during the last twelve months? a) in wrists and fingers, b) in elbows and forearms, c) in neck, d) in shoulders, e) in hip and lower back, f) in feet‘ was classified so that answers: ‘cannot say’,’ not at all’ and ‘sometimes’ were coded 0 (no symptoms), quite often was 1, often was 2, and very often was 3. In addition, the question ‘16) Have you suffered a) sleeping disorders/disturbances, b) depression, c) exhaustion at work, d) substance addiction, e) anxiety or f) fear situations during the last 12 months?’ were codified in the same way. In the first analysis background information (age, gender, marital status, education and occupation), daily usage of computers at work (questions 11b and 11e) and symptom questions 13aef and 16aef were analysed with independent samples ManneWhitney U-test. In analyses of employed and unemployed persons we compared groups: 1) respondents, who had quite often or more often sleeping disorders/disturbances and 2) respondents, had not quite often or more often sleeping disorders/disturbances. The same analyses were also made for subgroups of women and men. In the second analysis of independent samples ManneWhitney U-test we used the same questions (background information, usage
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of computers at work and symptoms) as in first analysis and compared groups: 1) employed respondents who had quite often or more often sleeping disorders/disturbances and 2) unemployed respondents, who had quite often or more often sleeping disorders/ disturbances. The same analyses were also made for subgroups of women and men. In this study p-value 0.05 was chosen. 3. Results 3.1. Background information A total of 6121 responses arrived (during 2002e2003) and the response percent was 41. The mean age standard deviation was 41.3 13.1 years. For all respondents 4368 (71.4%) persons were at work and 1599 (26.1%) were unemployed persons. In addition 2.5% of responses were missing. Table 1 shows background information and the results of all employed persons, workers with sleeping disorders/disturbances, female workers with sleeping disorders/ disturbances and male workers with sleeping disorders/disturbances. In the question 11b usage of a desktop computer at work and 11e usage of a portable computer or mini-computer at work, there are the amounts of ‘daily’ answers. In the part on the question 13aef and in the part on the question 16aef Table 1 shows the amount of answers ‘quite often’, ‘often’ and ‘very often’.
259
All of 1016 (16.6%) respondents reported that they suffered quite often or more often sleeping disorders/disturbances during the last 12 months. Of those 708 (69.7%) were employed and 276 (27.2%) were unemployed (3.1% missing). From unemployed persons with quite often or more often sleeping disorders/disturbances 48 (17.4%) used a daily desktop computer at leisure and 3 (1.1%) used daily portable computers or mini-computers at leisure. From the employed respondents 241 (34.0%) used daily desktop computer at leisure and 42 (5.9%) used daily portable computers or minicomputers at leisure. 3.2. Results of an independent sample ManneWhitney U-test Table 2 shows the analyses of the background information, questions 13aef (physical symptoms) and 16bef (mental symptoms) in comparison groups: all workers with and without sleeping disorders/disturbances, female workers with and without sleeping disorders/disturbances and male workers with and without sleeping disorders/disturbances. In analyses of all workers with and without sleeping disorders/disturbances there were significant differences in age, in gender, in usage of desktop computer at leisure, and in all symptoms. In the women’s and men’s data the significant differences were in age and in all symptoms. In addition in the men’s data (Table 2) there is difference in marital status.
Table 1 A summary of background information from all employed persons, employed persons with sleep disorders/disturbances, female and male employed persons with sleep disorders/disturbances, the daily usage of the computers at work, mental symptoms and experienced pain, numbness or aches (amounts of positive answers including answers; ‘quite often’, ‘often’, ‘very often’). Topics of questions and choices
Q3 Marital status Single Married or live-in Divorced Widow or widower Q5 Education Comprehensive school Matriculation Vocational school Vocational high school University Q6 Occupation Enterpriser Farmer Upper-level white-collar workersa Lower-level white-collar workersb Blue-collar workersc Home work, student Other Q11 Use at work (daily) b) Desktop computer e) Portable computer or mini-computer Q13 Experienced pain, numbness or aches a) In wrists or fingers b) In elbows or forearms c) In neck d) In shoulders e) In hip and lower back f) In feet Q16 Mental symptoms a) Sleeping disorders/disturbances b) Depression c) Exhaustion at work d) Substance addiction e) Anxiety f) Fear situations a b c
All employed persons
%
Workers with sleeping disorders/ disturbances
%
Female workers with sleeping disorders/ disturbances
%
Men workers with sleeping disorders/ disturbances
%
768 3218 328 48
17.6 73.8 7.5 1.1
129 489 80 9
18.2 69.2 11.3 1.3
90 290 58 6
20.3 65.3 13.1 1.4
39 197 22 3
14.9 75.5 8.4 1.1
586 349 1208 1534 679
13.5 8.0 27.7 35.2 15.6
96 61 171 259 118
13.6 8.7 24.3 36.7 16.7
62 39 91 181 71
14.0 8.8 20.5 40.8 16.0
34 22 79 77 47
13.1 8.5 30.5 29.7 18.1
366 105 971 1150 1548 48 171
8.4 2.4 22.3 26.4 35.5 1.1 3.9
59 12 171 228 203 11 22
8.4 1.7 24.2 32.3 28.8 1.6 3.1
27 8 89 172 128 8 11
6.1 1.8 20.1 38.8 28.9 1.8 2.5
32 4 82 55 75 3 10
12.3 1.5 31.4 21.1 28.7 1.1 3.8
2728 426
62.5 9.8
468 73
66.1 10.3
300 25
67.4 5.6
167 48
64.0 18.4
855 607 2194 1338 1396 991
19.6 13.9 50.2 30.6 31.9 22.7
246 181 513 354 351 277
34.8 25.5 72.4 50.0 49.5 39.1
178 131 355 248 229 173
40.1 29.4 79.8 55.7 51.5 38.9
67 49 156 105 122 104
25.7 18.8 59.8 40.3 46.7 39.9
708 350 853 68 242 108
16.2 8.0 19.4 1.6 5.5 2.4
225 391 37 150 74
31.8 55.2 5.2 21.2 10.5
148 239 16 101 51
33.3 53.7 3.6 22.7 11.5
77 152 21 49 23
29.5 58.2 8.0 18.8 8.8
Administrative or managerial duties, designing, research, teaching. Clerical duties and supervision. Industrial workers, distributive and service trade.
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Table 2 Comparison between workers with and without sleep disorders/disturbances, female workers with and without sleep disorders/disturbances and male workers with and without sleep disorders/disturbances, (with independent samples ManneWhitney U-test analyses) for backgroud information, daily usage of computers, physical and mental symptoms (amounts of positive answers to symptoms including answers; ‘quite often’, ‘often’, ‘very often’). Comparison groups with ManneWhitney U-test
Workers with and without sleeping disorders/disturbances Asymp. Sig. (2-tailed)
Female workers with and without sleeping disorders/disturbances Asymp. Sig. (2-tailed)
Male workers with and without sleeping disorders/disturbances Asymp.Sig. (2-tailed)
Age Gender Marital status Education Occupation Q11b) Use of desktop computer at work (daily) Q11e) Use of portable computer or mini-computer (daily) Q13 Experienced pain, numbness or aches a) In wrists or fingers b) In elbows or forearms c) In neck d) In shoulders e) In hip and lower back f) In feet Q16 Mental symptoms b) Depression c) Exhaustion at work d) Substance addiction e) Anxiety f) Fear situations
<0.001** <0.001** 0.085 0.311 0.010** 0.029**
<0.001** e 0.725 0.959 0.051 0.213
<0.001** e 0.030** 0.271 0.031** 0.115
0.585
0.579
0.176
<0.001** <0.001** <0.001** <0.001** <0.001** <0.001**
<0.001** <0.001** <0.001** <0.001** <0.001** <0.001**
<0.001** 0.001** <0.001** <0.001** <0.001** <0.001**
<0.001** <0.001** <0.001** <0.001** <0.001**
<0.001** <0.001** 0.001** <0.001** <0.001**
<0.001** <0.001** <0.001** <0.001** <0.001**
**Significant at p < 0.05.
Table 3 shows the results of a comparison between all employed and unemployed persons, female employed and unemployed persons and male employed and unemployed persons with sleeping disorders/disturbances. In the analysis of all employed and unemployed persons with sleeping disorders/disturbances there were significant differences in education, in occupation, in usage of desktop computer at leisure, in usage of portable computer or minicomputer at leisure, in some physical symptoms Q13e-f and in all mental symptoms. In the women’s data (Table 3) there are no significant differences in substance addiction, and in men’s data
there are not differences in depression and in fear situations. In addition, in the men’s data (Table 3) there are differences in marital status. 4. Discussion 4.1. Evaluation of methods In this study the population was 15 000 Finns and the amount of responses were 6121 (41%), which is quite large. Therefore, it was
Table 3 Comparison between employed and unemployed persons with sleep disorders/disturbances, female employed and unemployed persons with sleep disorders/disturbances, and male employed and unemployed persons with sleep disorders/disturbances, (with independent samples ManneWhitney U-test analyses) for backgroud information, daily usage of computers, physical and mental symptoms (amounts of positive answers to symptoms including answers; ‘quite often’, ‘often’, ‘very often’). Comparison groups with ManneWhitney U-test
Employed and unemployed persons with sleeping disorders/ disturbances Asymp. Sig. (2-tailed)
Age Gender Marital status Education Occupation Q8b) Use of desktop computer at leisure (daily) Q8e) Use of portable computer or minicomputer at leisure (daily) Q13 Experienced pain, numbness or aches a) In wrists or fingers b) In elbows or forearms c) In neck d) In shoulders e) In hip and lower back f) In feet Q16 Mental symptoms b) Depression c) Exhaustion at work d) Substance addiction e) Anxiety f) Fear situations
0.629 0.913 0.008** <0.001** <0.001** <0.001** 0.001**
e
e
0.351 <0.001** <0.001** <0.001** 0.077
0.001** <0.001** <0.001** 0.001** 0.005**
0.591 0.801 0.543 0.895 <0.001** <0.001**
0.527 0.633 0.091 0.545 0.008** <0.001**
0.058 0.223 0.170 0.265 0.010** 0.003**
0.016** <0.001** 0.014** 0.001** 0.007**
0.071 <0.001** 0.546 0.011** 0.015**
0.118 <0.001** 0.006** 0.018** 0.230
**Significant at p < 0.05.
Employed and unemployed women with sleeping disorders/ disturbances Asymp. Sig. (2-tailed)
Employed and unemployed men with sleeping disorders/ disturbances Asymp. Sig. (2-tailed)
0.335
0.049**
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possible to make analyses on the subgroup of persons, who reported quite often or more often sleep disorders/disturbances. In addition in our earlier article (Korpinen and Pääkkönen, 2009) we reported, that in this Finnish working-age population 59% had some or more sleeping disorders/disturbances and sleep disorders/ disturbances were associated with the use of a desktop computer in all data and in the women’s data. Because so many respondents have the sleep disorders/disturbances symptoms and the sleep disorders/disturbances had associations, it was interesting to make more analyses from this topic. However, one of the difficulties with this study is that it is basing sleep disorders on one question in a larger survey. There is no clarity as to the type of sleep disorders occurring. This is one weakness of this study. In this article, we used cases, which had quite often or more often sleep disorders/disturbances. From our data it is not possible to say exactly what sleep disorders respondents had and how difficult it is. It is also important to take into account the analyses of results that our data included only selfreported symptoms. It is not same as sleep disorder diagnosis. Our data is quite old, because we collected it in 2002e2003. For example respondents’ usage of different devices can be nowadays different than what it was when they answered the questionnaire. However, physical symptoms and mental symptoms are perhaps more permanent parameters than the usage of computers or mobile phones. Therefore our results are still relevant. Different types of biases were also included in the study. The questionnaire or questions can influence participants and only the active persons participated in the questionnaire. Because the questionnaire included only one question regarding the sleep disorders/disturbances it is possible that persons who are interested in sleep disorders did not answer. In addition respondents’ opinions can change quite quickly as the technology develops. Not everyone understands the physical or mental symptoms in the same way and the questionnaire did not include all possible questions or symptoms. There can be other factors, which can influence the sleep disorders, for example, atmosphere in workplace. 4.2. Evaluation of amount symptoms In our data 16.6% respondents reported that he or she suffered quite often or more often sleeping disorders/disturbances during the last 12 months. Lallukka et al. (2010) reported that in their questionnaire surveys the prevalence of sleep complaints was 24% among women and 20% among men aged 40e60-year-old employees of the City of Helsinki in Finland. According by Buscemi et al. (2005) and Ohayon and Partinen (2002) 10e35% of persons suffer from insomnia symptoms. So our result (16.6%) was quite similar that have been published in this area. In all employed persons’ data, 50.2% of persons had experienced quite often or more pain, numbness or aches in the neck, 30.6% had it in the shoulders and 31.9% in the hip and lower back. In the group of workers with sleep disorders/disturbances 72.4% had experienced quite often or more pain, numbness or aches in the neck, 49.5% in the hip and lower back and 50.0% in the shoulders. Regarding mental symptoms the values are the following: employed persons without sleep disorders/with sleep disorders: depression 8%/31.8%, exhaustion at work 19.4%/55.2%, anxiety 5.5%/ 21.2%, and fear situations 2.4%/10.5%. In other Finnish study (Perkiö-Mäkelä et al., 2006), there was for example: pain in the neckeshoulder 48%, pain in the arms and shoulders 32%, pain in the hip and lower back 28%, weakness 28%, insomnia 25% and pain in the hips and legs 24%. In our data of all employed persons, the values are almost a similar amount as in the other Finnish study (Perkiö-Mäkelä et al., 2006). However, the other study (PerkiöMäkelä et al., 2006) was based on interviews by phone.
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In Ohayon and Sagales (2010) “study prevalence of insomnia and sleep characteristics in the general population of Spain” participants with insomnia symptoms were more frequently treated for a physical disease. In addition, in other epidemiological studies, where participants with insomnia were more likely to report poor health and various diseases for example asthma, chronic bronchitis, rheumatic disease, non treated hypertension, heart diseases or painful physical affliction (Gislason and Almqvist, 1987; Klink and Quan, 1987; Foley et al., 1995; Ohayon et al., 1997a,b; Newman et al., 1997; Schwartz et al., 1999; Andersson et al., 1999). In our data many persons with sleep disorders/disturbances had also other symptoms. 4.3. Comparison between workers with sleep disorders/ disturbances and without sleep disorders/disturbances When comparing all workers with and without sleeping disorders/disturbances there were significant differences in age, gender, daily use of desktop computer at work, and in all symptoms (Table 2). This results supported earlier studies, which found that persons with insomnia were more frequently treated for a physical disease (Gislason and Almqvist, 1987; Klink and Quan, 1987; Foley et al., 1995; Ohayon et al., 1997a,b; Newman et al., 1997; Schwartz et al., 1999; Andersson et al., 1999; Ohayon and Sagales, 2010). In the women’s and men’s data (Table 2), there are almost the same differences as in all employed persons with sleep disorders/disturbances data. Only in the men’s data was there a significant difference in marital status, which is not in the other comparisons. Table 2 shows that there are significant differences in amounts of mental symptoms between persons with and without sleep disorders sleeping disorders/disturbances. However mental health problems can cause sleep disorders. For example Perlman et al. (2006) described that disturbed sleep is a hallmark symptom of depression and Gillin et al. (1996) described that with over 80% of those diagnosed reporting disturbed sleep. Sleep disturbances can also predict depression onset. (Breslau et al., 1997; Chang et al., 1997; Cuijpers et al., 2006; Hatzinger et al., 2004; Lustberg and Reynolds, 2000; Perlis et al., 1997, 2006). 4.4. Comparison between employed and unemployed persons with sleep disorders/disturbances We also studied employed and unemployed persons, who reported that they had quite often or more often sleep disorders/ disturbances. In the all persons comparison (Table 3) there were significant differences in education, in occupation, in usage of computers at leisure, in all mental symptoms, and in some physical symptoms (pain in the hip and lower back and in the feet). It is possible that some respondents were unemployed because they had an ache, pain or numbness in the hip and lower back or in the feet. According to the Finnish statistical office in 2006 over 112 600 Finnish workers received disability pensions based on mental health problems (Official Statistics of Finland, 2009). This can explain the significant differences in our results in mental symptoms between groups of employed and unemployed persons. In addition in our earlier article (Korpinen and Pääkkönen, 2011) we reported that, unemployed middle-aged (45 years old or older) people did not use, e.g., the Internet as much as people in general. This can also influence to results. From Table 3 we can find that women’s (with sleep disorders/ disturbances) and men’s (with sleep disorders/disturbances) results are little different. For example in the women’s data there are no significant differences in substance addiction and in the men’s data there are not differences in depression and in fear situations. Karlqvist et al. (2002) studied also the difference between genders.
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They found that women’s work tasks were more monotonous than men’s. Women also had less breaks and they felt more work stress and musculoskeletal disorders. Pressure due to time constraints caused women to have more symptoms while men had fewer symptoms. It is quite easy to understand that also in our comparison we found few differences in comparison of the women’s groups and in comparison of men’s groups. In the future studies, it is important to take account that there are differences in sleep disorders between female and male employed and unemployed persons. 5. Conclusion In conclusion, it can be stated that 16.2% of Finnish workers suffered quite or more often sleep disorders/disturbances. Of those workers, 72.4% had experienced pain, numbness and aches in the neck, when from all employed persons 50.2% had the same symptoms. When comparing employed persons with and without sleep disorders/disturbances we found significant differences in self-reported physical symptoms and mental symptoms. In addition there were differences in the usage of desktop computer at leisure. When comparing employed and unemployed persons with sleep disorders we found also differences in physical symptoms in the hip and lower back, and in the feet and in some mental symptoms. There were also differences in the usage of computers and in education. In the future, it is important to take account that persons with sleep disorders also have other differences e.g., in symptoms as persons without sleep disorders. In addition, the situation is different if persons are employed or unemployed. Acknowledgements The assistance of the staff (Suuronen, Latva-Teikari and Lehtelä) of Department of Energy and Process Engineering, Environmental Health, Tampere University of Technology is gratefully acknowledged. Special thanks go to Professor Irma Virjo, Faculty of Medicine, Tampere University, for her advice on designing the questionnaire and to M.Sc Maarit Pakarinen, SPSS Finland Oy, for her advice on statistical analyses. References Andersson, H.I., Ejlertsson, G., Leden, I., Schersten, B., 1999. Impact of chronic pain on health care seeking, self care, and medication. Results from a populationbased Swedish study. J. Epidemiol. Commun. Health 53, 503e509. Arber, S., Bote, M., Meadows, R., 2009. Gender and socio-economic patterning of self-reported sleep problems in Britain. Soc. Sci. Med. 68, 281e289. Breslau, N., Roth, T., Rosenthal, L., Andreski, P.S., 1997. Daytime sleepiness: an epidemiological study of young adults. Am. J. Public Health 87, 1649e1653. Buscemi, N., Vandermeer, B., Friesen, C., Bialy, L., Tubman, M., Ospina, M., et al., 2005. Manifestations and management of chronic insomnia in adults. Evid. Rep. Technol. Assess. (Summ) 125, 1e10. Chang, P.P., Ford, D.E., Mead, L.A., Cooper-Patrick, L., Klag, M., 1997. Insomnia in young men and subsequent depression: the Johns Hopkins precursors study. Am. J. Epidemiol. 146, 105e114. Cuijpers, P., Beekman, A., Smit, F., Deeg, D., 2006. Predicting the onset of major depressive disorder and dysthymia in older adults with subthreshold depression: a community based study. Int. J. Geriatr. Psychiatr. 21, 811e818. Daley, M., Morin, C.M., Leblanc, M., Gregoire, J.P., Savard, J., Baillargeon, L., 2008. Insomnia and its relationship to health-care utilization, work absenteeism, productivity and accidents. Sleep Med. 10, 427e438. Erman, M., Guiraud, A., Joish, V., Lerner, D., 2008. Zolpidem extendedrelease 12.5 mg associated with improvements in work performance in a 6-month randomized, placebo-controlled trial. Sleep 31, 1371e1378. Foley, D.J., Monjan, A.A., Brown, S.L., Simonsick, E.M., Wallace, R.B., Blazer, D.G., 1995. Sleep complaints among elderly persons: an epidemiologic study of three communities. Sleep 18, 425e432. Gillin, J.C., Inkwell-Israel, S., Erman, M., 1996. Sleep and sleep wake disorders. In: Tasman, A., Kay, J., Lieberman, J.C. (Eds.), Psychiatry. W.B. Saunders Company, Philadelphia, pp. 1217e1248. Gislason, T., Almqvist, M., 1987. Somatic diseases and sleep complaints: an epidemiological study of 3201 Swedish men. Acta Med. Scand. 221, 475e481.
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