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Independent and combined associations between screen time and physical activity and perceived stress among college students
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Addictive Behaviors Addictive Behaviors
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Please cite this article as: Y. Ge, S. Xin, D. Luan, Z. Zou, X. Bai, M. Liu, Q. Gao, Independent and combined associations between screen time and physical activity and perceived stress among college students, Addictive Behaviors Addictive Behaviors (2019), doi: https://doi.org/10.1016/j.addbeh.2019.106224
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Independent and combined associations between screen time and physical activity and perceived stress among college students Yinjian Gea, Shimeng Xina, Dechun Luanb, Zhili Zoua, Xue Baia, Mengting Liua, Qian Gaoa Author affiliations a
School of Public Health China Medical University, Shenyang, China.
b
Institute for Nutrition and Food Hygiene, Liaoning Provincial Center for Disease
Control and Prevention, Shenyang, China Author E-Mail Yinjian Ge, E-Mail: [email protected] Shimeng Xin, E-Mail: [email protected] Dechun Luan, E-Mail: [email protected] Zhili Zou, E-Mail: [email protected] Xue Bai, E-Mail: [email protected] Mengting Liu, E-Mail: [email protected] Corresponding Author Qian Gao, School of Public Health China Medical University No.77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning Province, P.R. China, 110122
E-Mail: [email protected] Declarations of interest: None.
Independent and combined associations between screen time and physical activity and perceived stress among college students Abstract Although both screen time (ST) and physical activity (PA) are associated with stress, independent and combined associations between ST and PA, and perceived stress among college students, have remained unclear. The present study included 1137 undergraduate medical students from a university in Shenyang, Northeast China. PA and perceived stress were measured using the International Physical Activity Questionnaire (IPAQ)-Long Form and the Chinese Perceived Stress Scale (CPSS), respectively.
ST
and
students’
characteristics
were
determined
using
a
self-administered questionnaire. Data were analyzed using the independent t-test, Pearson Chi-squared test, and logistic regression. After adjusting for potential confounding factors, females reporting high ST (HST, ST >6 h/day) were more likely to experience stress than those reporting low ST (LST, ST ≤6 h/day) (OR = 1.557), while those reporting light- and moderate-intensity PA (LMPA) were more likely to experience stress than those reporting vigorous-intensity PA (VIPA) (OR = 1.674). Analysis of the combined effects of PA and ST showed that, among female students, those reporting both LST and LMPA (OR = 2.174), both HST and VIPA (OR =
2.088), and both HST and LMPA (OR = 2.797) were more likely to experience stress compared to those reporting both LST and VIPA (the reference category). The present study confirmed that LST and VIPA were independently and concurrently associated with significantly lower stress among college students, suggesting that promoting PA and reducing ST might be an effective way to reduce perceived stress among college students. Keywords: physical activity; screen time; perceived stress; college students Abbreviations PA physical activity ST screen time IPAQ the International Physical Activity Questionnaire CPSS the Chinese Perceived Stress Scale HST high screen time LST low screen time VIPA vigorous-intensity physical activity LMPA light- and moderate-intensity physical activity 1. Introduction With the scientific and technological developments and life style changes observed nowadays, individuals have been facing more and more health problems,
including stress. Accordingly, Waghachavare VB et al. (2013) showed that stress had both physical and psychological effects on individuals, such as headaches, gastrointestinal discomfort, poor memory, and difficulty concentrating. Moreover, one of the most important issues at present has been the high proportion of college students experiencing stress. Indeed, several studies have reported high stress rates among college students in Pakistan (60%) (Waqas A et al., 2015), Thailand (61%) (Saipanish R, 2003), and Malaysia (42%) (Sherina MS et al., 2004). College students are exposed to a number of stressors, such as change of residence (Arnett JJ, 2000), increased responsibility, peer pressure, different learning methods, and schedules (Gall TL et al., 2000). These unique changes college students face places them under a different type of stress. Indeed, studies have confirmed that college students experience a unique type of stress, called academic stress (Waqas A et al., 2015; Al Rasheed F et al., 2017). Hence, efforts toward studying stress among college students are meaningful. A variety of factors can influence stress, one of which is physical activity (PA). Physical inactivity has been identified as the fourth leading risk factor for global mortality (WHO, 2010). Moreover, Childs and de Wit (2014) found that, among healthy adults, those who self-reported regular exercise had fewer negative emotional consequences of stress. After using an objective method for measuring PA, Gerber et al. (2017) found that PA could influence physiological and psychological stress resilience in young adults. Furthermore, the World Health Organization (WHO) recommends at least 150 min of moderate-intensity aerobic PA or at least 75 min of
vigorous-intensity aerobic PA throughout the week for adults aged 18–64 years (WHO, 2010). Despite such recommendations, one study indicated that the global age-standardized prevalence of physical inactivity was 27.5% (Guthold, R. et al., 2018), while a global survey showed that college students had a physical inactivity prevalence of 41.4% (Pengpid S et al., 2015), which was much higher than the global age-standardized prevalence (Guthold, R. et al., 2018). Therefore, the association between PA and stress status among college students cannot be ignored. The use of electronic media has also been associated with stress. Accordingly, Thomée et al. (2011) associated a self-reported higher mobile phone use with current stress among young adults. Another study showed that a self-reported high combined use of computers and mobile phones at baseline was associated with an increased risk of reporting prolonged stress among females (Thomée S et al., 2007). College students integrate electronic media into their everyday lives (Haverila, M., 2013) and have autonomy over their use, without parent-imposed constraints (Fossum et al., 2014). The Academy of Pediatrics guidelines (2001) recommend that screen time (ST), which is the total time spent on different types of electronic media, such as watching TV, using computers, playing video games, and e-reading, should not exceed 2 h per day. However, one study showed that many college students had exceeded this recommendation (Feng Q et al., 2014), while another found increasing ST among college students (Buckworth J and Nigg C, 2004). Therefore, this trend toward increasing ST among college students may be associated with stress. In recent years, many studies have sought to better understand how the
combination of PA and ST leads to certain health problems. Accordingly, studies have found that adults with insufficient PA and high ST were more likely overweight (Liao et al., 2011), high PA and low ST were associated with reduced prevalence of depressive problems (Feng Q et al., 2014), and low PA and high ST were associated with increased risks of mental health problems and poor sleep quality (Wu X et al., 2015). However, to the best of our knowledge, limited research has been available on the effects of PA and ST on stress among college students. Thus, to investigate both independent and combined associations between ST and PA and perceived stress among college students, a cross-sectional study among undergraduate students was conducted at a university in Northeast China. 2. Methods In 2017, a cross-sectional survey was conducted among undergraduate medical students attending grades 1 through 3 at a university located in Shenyang, Northeast China. The ethics committee of China Medical University approved the study, and informed consent was obtained from all students. Self-reported data regarding gender, age, grade, specialization, home location, and monthly living expenses, as well as ST, PA, sleep duration, and perceived stress, were obtained using a paper–pencil questionnaire. The questionnaire, which was filled out in the classroom, took approximately 20–30 min to complete. Finally, 1137 undergraduate students were enrolled in this study. 2.1. Assessment of ST, PA, and the combination thereof
Students were asked to report the number of hours per day they spent on personal computers, smartphones, and tablets on weekdays and weekends using the following response options: “0 h,” “<1 h,” “1 h,” “2 h,” “3 h,” “4 h,” “5 h,” and “≥6 h” with “<1 h” = 0.5 h and “≥6 h” = 6.5 h. The average daily ST for each type of electronic media was computed by multiplying the average reported weekday time by 5 and the average weekend time by 2, summing both values, and then dividing by 7. The total daily ST was computed by summing the daily ST for all three types of electronic media. Given that the median group value for ST was equal to 6 h/day, the present study categorized high ST as >6 h/day (HST) and low ST as ≤6 h/day (LST). PA among college students was assessed using the Chinese version of the International Physical Activity Questionnaire (IPAQ)-Long Form (Qu NN and Li KJ, 2004), which allowed us to estimate the time spent on walking and moderate- and vigorous-intensity PA during the last seven days. This questionnaire had already shown good reliability and validity among college students (Qu NN and Li KJ, 2004). Based on the classification standard (Fan M et al., 2014), PA was categorized as either light-, moderate-, or vigorous-intensity. However, considering the low number of college students reporting light- and moderate-intensity PA, both categories were combined into one group. Hence, PA among college students was divided into two categories: light- and moderate-intensity PA (LMPA) and vigorous-intensity PA (VIPA). Based on the categorization of PA and ST, the combination of ST and PA yielded four categories: LST and VIPA (the reference category), LST and LMPA, HST and
VIPA, and HST and LMPA. 2.2. Assessment of perceived stress The Chinese Perceived Stress Scale (CPSS) (Cohen S et al., 1983), which has good reliability and validity among the general population of China (Yang TZ and Huang HT, 2003), was used to analyze perceived stress levels among college students during their daily study lives. The scale had 14 self-assessment items, with five answers per project, and adopted a 5-point (0 to 4) Likert grading method. The sum of each score was used as the stress scale score, which can range from 0 to 56 points. The total stress score indicated the level of stress each individual perceived, wherein a higher score suggested greater perceived stress. Considering previous research, showing that the ideal CPSS threshold score for stress among the general population is 25/26 (Yang TZ and Huang HT, 2003), total scores ≥26 and ≤25 were used to indicate high stress (coded as 1) and low stress (coded as 0), respectively. 2.3. Assessment of potential confounding factors Age, grade, specialization, home location, monthly living expenses, and sleep duration were considered potential confounding factors. Accordingly, grade was categorized as first, second, and third; specialization was categorized as clinical and non-clinical; home location was categorized as urban (in or from the city), town (larger than the countryside but smaller than the city), and rural (in or from the countryside); and monthly living expenses were categorized as ≤¥ 1000, ¥ 1001–1500, and ≥¥ 1501.
2.4. Statistical analysis Descriptive analyses were presented as means (standard deviation, SD) for continuous variables and numbers (percentages, %) for categorical variables. Differences in characteristics, by gender, were determined using the independent t-test for continuous variables and Pearson Chi-squared test for categorical variables. Differences in perceived stress among college students by gender, according to ST, PA, and a combination of both, were determined using the Pearson Chi-squared test. Independent and combined associations between ST and PA and perceived stress among college students by gender were determined using logistic regression models after adjusting for potential confounding factors, while odds ratios (OR) and their 95% confidence intervals (CI) were calculated. Statistical analysis was performed using the Statistical Package for the Social Sciences version 20.0, and statistical significance was set at P < 0.05. 3. Results 3.1. Student characteristics Table 1 presents the college students’ characteristics by gender. Overall, the students, 65.5% of whom were female, had an average age of 19.93 (1.07) years (range 17–23 years). Moreover, 52.3% reported LMPA, while 52.2% reported LST. Compared to female students, male students were older and had a higher prevalence of VIPA (age: P < 0.001; PA: P = 0.002). However, significant gender differences in other variables were not observed.
3.2. Distribution of perceived stress among the college students by gender Table 2 summarizes the distribution of perceived stress among college students by gender according to ST, PA, and the combination of ST and PA. Accordingly, more female students reporting HST experienced stress compared to those reporting LST (P = 0.001), while fewer female students reporting VIPA experienced stress compared to those reporting LMPA (P = 0.001). There was significant difference in the proportion of female students with perceived stress across the ST/PA categories (P < 0.001). After further pairwise comparisons (data not shown in the table), we found that more female students reporting both HST and LMPA experienced stress compared to those reporting both LST and VIPA (P < 0.001). However, proportional differences in perceived stress according to ST, PA, and the combination of ST and PA were not observed among male students. 3.3. Independent and combined associations between ST and PA and perceived stress among college students by gender Binary logistic regression was conducted to analyze independent associations between ST and PA and perceived stress after adjusting for potential confounding factors (Table 3). Among female students, those reporting HST (OR = 1.557, 95% CI = 1.129–2.145; P = 0.007) and LMPA (OR = 1.674, 95% CI = 1.204–2.329; P = 0.002) were more likely to experience stress. However, no significant independent associations between ST and PA and perceived stress were observed among male students.
Table 4 presents the OR for perceived stress by gender, according to combined ST and PA categories, determined using binary logistic regression after adjusting for potential confounding factors. Among female students, those reporting both LST and LMPA (OR = 2.174, 95% CI = 1.335–3.540; P = 0.002), both HST and VIPA (OR = 2.088, 95% CI = 1.250–3.490; P = 0.005), and both HST and LMPA (OR = 2.797, 95% CI = 1.747–4.477; P < 0.001) were more likely to experience stress compared to those reporting both LST and VIPA. However, there were no significant combined associations between ST and PA and perceived stress among male students. 4. Discussion After investigating independent and combined associations between ST and PA and perceived stress among college students, our findings indicated that, among female students, those reporting HST and LMPA were more likely to experience stress. Moreover, our results showed that the combined effects of PA and ST were significantly associated with perceived stress among females, but not males. The present study found that students with LMPA were more likely to experience stress. Regular PA has many beneficial effects for health, such as promoting cardiorespiratory fitness (Aires L et al., 2010) and reducing the risk of ischemic heart disease (Batty GD, 2002), stroke (Batty GD and Lee IM, 2002), diabetes (Jeon CY et al., 2007), and cognitive disorders (Larson et al., 2006). Several studies have also showed that PA was associated with stress. Indeed, Vankim and Nelson (2013) found that students who met vigorous PA recommendations were less likely to report poor
perceived stress, while Gerber et al. (2014) associated vigorous PA with lower stress among young adults. Another study also showed that regular exercise could protect against the negative emotional consequences of stress (Childs and de Wit, 2014). Possible explanations for PA’s effects on stress could include its beneficial effects on brain neurotransmitters, as well as on increasing levels of motivation and positive emotions, reducing stress and pain (Ekeland E et al., 2004; Paluska SA and Schwenk TL, 2000). Meanwhile, one survey observed a clear negative correlation between stress and sleep quality (Almojali AI et al., 2017). This association could be mediated by PA, given that exercise regulates temperature and improves sleep onset through vasodilation for peripheral heat dissipation (Driver HS and Taylor SR, 2000). Thus, PA can decrease stress and improve behavioral and emotional regulations by positively affecting sleep quality. The present study also revealed that participants with high ST were more likely to experience stress. The Academy of Pediatrics guidelines (2001) recommend that the ST of children and teenagers is not more than 2 h per day, but the median value for ST of college students was 6 h per day in our study, which was much higher than the recommendation for children and teenagers. Indeed, studies have shown that high ST was associated with poor health attributes, such as overweight and obesity (Lane et al., 2014), depression risk (Liu et al., 2015), and low self-esteem (Russ et al., 2009). Moreover, several studies had already indicated that increased self-reported use of electronic media was related to stress among young adults (Thomée et al., 2011) or females (Thomée et al., 2007). One study also found that increased use of information
and communication technology was associated with stress among young adults (Thomée et al., 2010), possibly because ST contributes to a sedentary lifestyle, which was highly correlated with stress. Accordingly, An et al. (2015) found that prolonged sedentary time was associated with risk for stress symptoms, and reducing sedentary behaviors could be one approach toward reducing perceived stress. Moreover, Trinh L et al. (2015) showed that high ST was associated with poor mental health, while Opoku-Acheampong et al. (2017) found that stress levels were negatively correlated with self-reported mental health. Furthermore, ST may consume time that could have otherwise been used for other activities. As such, spending more time on screen-based activities could lead to less time spent on sleep. Despite the aforementioned potential mechanisms explaining the association between ST and perceived stress, some uncertainty exists regarding the causal relationship between electronic media use and stress. Indeed, Caplan (2010) found that students with high levels of perceived stress might be more inclined to show increased media use as a form of avoidant coping. Therefore, further research is needed to determine whether ST and stress are interrelated or whether both factors accompany each other. The present study also investigated the association between the combined effects of PA and ST and perceived stress among college students. Accordingly, our results showed that students reporting both HST and LMPA, both HST and VIPA, and both LST and LMPA were more likely to experience stress. One possible underlying reason could be a potential threshold where sufficient time spent on high PA compensates for high ST. One study also negatively correlated high ST with vigorous
PA among females (Melkevik et al., 2010). Several studies had already confirmed that the combination of ST and PA had an impact on physical and psychological health. Accordingly, one study showed that Japanese adults with insufficient PA and high ST were significantly more likely to become overweight (Liao et al., 2011). Moreover, Feng et al. (2014) found that high PA and low ST could reduce the prevalence of depressive problems, while Wu et al. (2015) revealed that low PA and high ST could increase the risks of mental health problems and poor sleep quality. Similarly, the present study also confirmed that the combined effects of ST and PA influenced health. Thus, increasing PA among individuals with prolonged exposure to electronic media might be a suitable approach toward reducing the risk of perceived stress. The present study found the interactions between gender and the two exposures (ST and PA) in their association with perceived stress were not significant (P = 0.143 for PA × Gender and P = 0.440 for ST × Gender, data not shown in results), and the three way interaction (ST × PA × Gender) was also not significant (P = 0.787, data not shown in results). This implies that gender does not affect the associations of ST and PA with perceived stress. However, significant gender differences in the effects of PA and ST on perceived stress were still observed, with complex underlying reasons. One study indicated that significant interpersonal sensitivity was more frequently observed among female than male students (Nyström, M.B.T. et al., 2018). Moreover, Troisi (2001) found that females were more likely to feel the stressful effects of negative interpersonal events, while Van Wijk and Kolk (1997) showed that females might selectively pay attention to bodily cues and were more likely to report
the symptoms they perceive to others. Another study found that males were more likely to use active and instrumental coping behaviors, while females were more likely to use passive and emotionally focused behaviors (Ptacek et al., 1992). Matud (2004) also found that, compared to males, females believed their life events were more negative and less controllable, and that their coping style was more emotionally focused. These differences in stress perception and coping style between males and females may promote increased vulnerability of females to stress despite similar PA and electronic media exposure. Some study limitations should be considered. First, considering the cross-sectional design employed herein, we could not establish causal inferences from the associations between ST and PA and perceived stress. Second, samples from only one university, located in Shenyang, Northeast China, were included. Thus, our results cannot be generalized to all college students. Third, some variables, such as ST and PA, were assessed using a self-reported questionnaire, which might influence actual associations due to common method bias (Podsakoff, P. M. et al., 2003). Indeed, studies have shown that self-reported variables (Montag, C. et al., 2015), as well as self-report assessments of technology use, such as ST (Araujo, T. et al., 2017; Junco, R, 2013), are typically biased. Therefore, objective measurements, such as those obtained by tracking via applications, are needed in future studies. Finally, although we controlled for some confounding factors, we could not adjust for all possible related variables, such as psychological symptoms, health complaints and so on. Mood (2010) reported that Logistic regression estimates are affected by omitted
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Table 1 Characteristics of Chinese college students by gender a Male(n=392)
Female(n=745)
All(n=1137)
P
Age (years)
20.08,1.12
19.85,1.03
19.93,1.07
<0.001*
Sleep duration (h/day)
8.26,0.91
8.25,0.80
8.26,0.84
0.907
Mean (SD)
N (%) Grade
0.938 First
54(13.8)
99(13.3)
153(13.5)
Second
240(61.2)
465(62.4)
705(62.0)
Third
98(25.0)
181(24.3)
279(24.5)
specialization
0.831 Clinical
299(76.3)
564(75.7)
863(75.9)
Non-clinical
93(23.7)
181(24.3)
274(24.1)
Home location
0.643 Urban
220(56.1)
421(56.5)
641(56.4)
Town
84(21.4)
177(23.8)
261(23.0)
Rural
88(22.4)
147(19.7)
235(20.7)
Month living expenses
0.321
≤ ¥1,000
120(30.6)
212(28.5)
332(29.2)
¥1,001-1,500
191(48.7)
362(48.6)
553(48.6)
≥¥1,501
81(20.7)
171(23.0)
252(22.2)
ST b
0.076 ≤6 h/day
219(55.9)
375(50.3)
594(52.2)
>6h/day
173(44.1)
370(49.7)
543(47.8)
PA c
0.002* LMPA d
180(45.9)
415(55.7)
595(52.3)
VIPA e
212(54.1)
330(44.3)
542(47.7)
Perceived stress
a
0.750 Low
273(69.6)
512(68.7)
785(69.0)
High
119(30.4)
233(31.3)
352(31.0)
Values are presented as mean (SD) or N (%) when appropriate. b ST: screen time. c PA: physical activity. d LMPA:
light- and moderate-intensity physical activity. e VIPA: vigorous-intensity physical activity. *P<0.05.
Table 2 The distribution of different perceived stress among Chinese college students by gender according to ST, PA, and a combination of ST and PA group by using the Pearson Chi-squared test a Male
Female
Perceived stress Low (n=273)
High (n=119)
ST b
Perceived stress
X2
P
1.471
0.225
Low (n=512)
High (n=233)
≤6 h/day 158(72.1) 61(27.9)
278(74.1)
>6h/day 115(66.5) 58(33.5)
234(63.2) 136(36.8)
PA c
0.270
248(75.2)
0.001*
11.384
0.001*
2.968
20.916
<0.001*
82(24.8)
0.397
>6h/day and LMPA
51(62.2)
31(37.8)
134(60.4)
88(39.6)
>6h/day and VIPA
64(70.3)
27(29.7)
100(67.6)
48(32.4)
≤6 h/day and LMPA
72(73.5)
26(26.5)
130(67.4)
63(32.6)
≤6 h/day and VIPA
86(71.1)
35(28.9)
148(81.3)
34(18.7)
a
10.276
264(63.6) 151(36.4)
VIPA e 150(70.8) 62(29.2) ST/PA f
P
97(25.9)
0.603
LMPA d 123(68.3) 57(31.7)
X2
Values are presented as N (%). b ST: screen time. c PA: physical activity. d LMPA: light- and moderate-intensity
physical activity. e VIPA: vigorous-intensity physical activity. f ST/PA: a combination of screen time and physical activity. *P<0.05.
Table 3 Independent associations between screen time and physical activity and perceived stress among Chinese college students by gender a Male n(%)
Female
OR(95%CI)
P
n(%)
OR(95%CI)
P
ST b ≤6 h/day
219(55.9)
ref.
375(50.3) ref.
>6h/day
173(44.1)
1.275(0.814,1.996)
VIPA d
180(45.9)
ref.
LMPA e
212(54.1)
1.055(0.673,1.652)
0.288
370(49.7) 1.557(1.129,2.145)
0.007*
PA c
a
415(55.7) ref. 0.816
330(44.3) 1.674(1.204,2.329)
0.002*
Adjusted for age, grade, specialization, home location, monthly living expenses and sleep duration and also
adjusted for ST (for PA) or PA (for ST).
b
ST: screen time.
c
PA: physical activity. d VIPA: vigorous-intensity
physical activity. e LMPA: light- and moderate-intensity physical activity. *P<0.05.
Table 4 Combined associations between screen time and physical activity and perceived stress among Chinese college students by gender a Male n(%) ST/PA b
OR(95%CI)
Female P
n(%)
OR(95%CI)
P
≤6 h/day and VIPA c
121(30.9) ref.
≤6 h/day and LMPA d
98(25.0) 0.775(0.419,1.435)
0.418
193(25.9) 2.174(1.335,3.540)
0.002*
>6h/day and VIPA
91(23.2) 0.935(0.505,1.732)
0.832
148(19.9) 2.088(1.250,3.490)
0.005*
>6h/day and LMPA
82(20.9) 1.402(0.752,2.615)
0.288
222(29.8) 2.797(1.747,4.477)
<0.001*
a
182(24.4) ref.
Adjusted for age, grade, specialization, home location, monthly living expenses and sleep duration.
b
ST/PA: a
combination of screen time and physical activity. c VIPA: vigorous-intensity physical activity. d LMPA: light- and moderate-intensity physical activity. *P<0.05.
Highlights 1. Females reporting high screen time (HST, ST >6 h/day) were more likely to experience stress than those reporting low screen time (LST, ST ≤6 h/day). 2. Females reporting light- and moderate-intensity PA (LMPA) were more likely to experience stress than those reporting vigorous-intensity PA (VIPA). 3. Female reporting both LST and LMPA, both HST and VIPA, and both HST and LMPA were more likely to experience stress compared to those reporting both LST and VIPA.
Conflict of interest The authors declare that they have no competing interests.
S0306-4603(19)30347-8 https://doi.org/10.1016/j.addbeh.2019.106224 AB 106224
To appear in:
Addictive Behaviors Addictive Behaviors
Received Date: Revised Date: Accepted Date:
24 March 2019 11 November 2019 13 November 2019
Please cite this article as: Y. Ge, S. Xin, D. Luan, Z. Zou, X. Bai, M. Liu, Q. Gao, Independent and combined associations between screen time and physical activity and perceived stress among college students, Addictive Behaviors Addictive Behaviors (2019), doi: https://doi.org/10.1016/j.addbeh.2019.106224
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Independent and combined associations between screen time and physical activity and perceived stress among college students Yinjian Gea, Shimeng Xina, Dechun Luanb, Zhili Zoua, Xue Baia, Mengting Liua, Qian Gaoa Author affiliations a
School of Public Health China Medical University, Shenyang, China.
b
Institute for Nutrition and Food Hygiene, Liaoning Provincial Center for Disease
Control and Prevention, Shenyang, China Author E-Mail Yinjian Ge, E-Mail: [email protected] Shimeng Xin, E-Mail: [email protected] Dechun Luan, E-Mail: [email protected] Zhili Zou, E-Mail: [email protected] Xue Bai, E-Mail: [email protected] Mengting Liu, E-Mail: [email protected] Corresponding Author Qian Gao, School of Public Health China Medical University No.77 Puhe Road, Shenyang North New Area, Shenyang, Liaoning Province, P.R. China, 110122
E-Mail: [email protected] Declarations of interest: None.
Independent and combined associations between screen time and physical activity and perceived stress among college students Abstract Although both screen time (ST) and physical activity (PA) are associated with stress, independent and combined associations between ST and PA, and perceived stress among college students, have remained unclear. The present study included 1137 undergraduate medical students from a university in Shenyang, Northeast China. PA and perceived stress were measured using the International Physical Activity Questionnaire (IPAQ)-Long Form and the Chinese Perceived Stress Scale (CPSS), respectively.
ST
and
students’
characteristics
were
determined
using
a
self-administered questionnaire. Data were analyzed using the independent t-test, Pearson Chi-squared test, and logistic regression. After adjusting for potential confounding factors, females reporting high ST (HST, ST >6 h/day) were more likely to experience stress than those reporting low ST (LST, ST ≤6 h/day) (OR = 1.557), while those reporting light- and moderate-intensity PA (LMPA) were more likely to experience stress than those reporting vigorous-intensity PA (VIPA) (OR = 1.674). Analysis of the combined effects of PA and ST showed that, among female students, those reporting both LST and LMPA (OR = 2.174), both HST and VIPA (OR =
2.088), and both HST and LMPA (OR = 2.797) were more likely to experience stress compared to those reporting both LST and VIPA (the reference category). The present study confirmed that LST and VIPA were independently and concurrently associated with significantly lower stress among college students, suggesting that promoting PA and reducing ST might be an effective way to reduce perceived stress among college students. Keywords: physical activity; screen time; perceived stress; college students Abbreviations PA physical activity ST screen time IPAQ the International Physical Activity Questionnaire CPSS the Chinese Perceived Stress Scale HST high screen time LST low screen time VIPA vigorous-intensity physical activity LMPA light- and moderate-intensity physical activity 1. Introduction With the scientific and technological developments and life style changes observed nowadays, individuals have been facing more and more health problems,
including stress. Accordingly, Waghachavare VB et al. (2013) showed that stress had both physical and psychological effects on individuals, such as headaches, gastrointestinal discomfort, poor memory, and difficulty concentrating. Moreover, one of the most important issues at present has been the high proportion of college students experiencing stress. Indeed, several studies have reported high stress rates among college students in Pakistan (60%) (Waqas A et al., 2015), Thailand (61%) (Saipanish R, 2003), and Malaysia (42%) (Sherina MS et al., 2004). College students are exposed to a number of stressors, such as change of residence (Arnett JJ, 2000), increased responsibility, peer pressure, different learning methods, and schedules (Gall TL et al., 2000). These unique changes college students face places them under a different type of stress. Indeed, studies have confirmed that college students experience a unique type of stress, called academic stress (Waqas A et al., 2015; Al Rasheed F et al., 2017). Hence, efforts toward studying stress among college students are meaningful. A variety of factors can influence stress, one of which is physical activity (PA). Physical inactivity has been identified as the fourth leading risk factor for global mortality (WHO, 2010). Moreover, Childs and de Wit (2014) found that, among healthy adults, those who self-reported regular exercise had fewer negative emotional consequences of stress. After using an objective method for measuring PA, Gerber et al. (2017) found that PA could influence physiological and psychological stress resilience in young adults. Furthermore, the World Health Organization (WHO) recommends at least 150 min of moderate-intensity aerobic PA or at least 75 min of
vigorous-intensity aerobic PA throughout the week for adults aged 18–64 years (WHO, 2010). Despite such recommendations, one study indicated that the global age-standardized prevalence of physical inactivity was 27.5% (Guthold, R. et al., 2018), while a global survey showed that college students had a physical inactivity prevalence of 41.4% (Pengpid S et al., 2015), which was much higher than the global age-standardized prevalence (Guthold, R. et al., 2018). Therefore, the association between PA and stress status among college students cannot be ignored. The use of electronic media has also been associated with stress. Accordingly, Thomée et al. (2011) associated a self-reported higher mobile phone use with current stress among young adults. Another study showed that a self-reported high combined use of computers and mobile phones at baseline was associated with an increased risk of reporting prolonged stress among females (Thomée S et al., 2007). College students integrate electronic media into their everyday lives (Haverila, M., 2013) and have autonomy over their use, without parent-imposed constraints (Fossum et al., 2014). The Academy of Pediatrics guidelines (2001) recommend that screen time (ST), which is the total time spent on different types of electronic media, such as watching TV, using computers, playing video games, and e-reading, should not exceed 2 h per day. However, one study showed that many college students had exceeded this recommendation (Feng Q et al., 2014), while another found increasing ST among college students (Buckworth J and Nigg C, 2004). Therefore, this trend toward increasing ST among college students may be associated with stress. In recent years, many studies have sought to better understand how the
combination of PA and ST leads to certain health problems. Accordingly, studies have found that adults with insufficient PA and high ST were more likely overweight (Liao et al., 2011), high PA and low ST were associated with reduced prevalence of depressive problems (Feng Q et al., 2014), and low PA and high ST were associated with increased risks of mental health problems and poor sleep quality (Wu X et al., 2015). However, to the best of our knowledge, limited research has been available on the effects of PA and ST on stress among college students. Thus, to investigate both independent and combined associations between ST and PA and perceived stress among college students, a cross-sectional study among undergraduate students was conducted at a university in Northeast China. 2. Methods In 2017, a cross-sectional survey was conducted among undergraduate medical students attending grades 1 through 3 at a university located in Shenyang, Northeast China. The ethics committee of China Medical University approved the study, and informed consent was obtained from all students. Self-reported data regarding gender, age, grade, specialization, home location, and monthly living expenses, as well as ST, PA, sleep duration, and perceived stress, were obtained using a paper–pencil questionnaire. The questionnaire, which was filled out in the classroom, took approximately 20–30 min to complete. Finally, 1137 undergraduate students were enrolled in this study. 2.1. Assessment of ST, PA, and the combination thereof
Students were asked to report the number of hours per day they spent on personal computers, smartphones, and tablets on weekdays and weekends using the following response options: “0 h,” “<1 h,” “1 h,” “2 h,” “3 h,” “4 h,” “5 h,” and “≥6 h” with “<1 h” = 0.5 h and “≥6 h” = 6.5 h. The average daily ST for each type of electronic media was computed by multiplying the average reported weekday time by 5 and the average weekend time by 2, summing both values, and then dividing by 7. The total daily ST was computed by summing the daily ST for all three types of electronic media. Given that the median group value for ST was equal to 6 h/day, the present study categorized high ST as >6 h/day (HST) and low ST as ≤6 h/day (LST). PA among college students was assessed using the Chinese version of the International Physical Activity Questionnaire (IPAQ)-Long Form (Qu NN and Li KJ, 2004), which allowed us to estimate the time spent on walking and moderate- and vigorous-intensity PA during the last seven days. This questionnaire had already shown good reliability and validity among college students (Qu NN and Li KJ, 2004). Based on the classification standard (Fan M et al., 2014), PA was categorized as either light-, moderate-, or vigorous-intensity. However, considering the low number of college students reporting light- and moderate-intensity PA, both categories were combined into one group. Hence, PA among college students was divided into two categories: light- and moderate-intensity PA (LMPA) and vigorous-intensity PA (VIPA). Based on the categorization of PA and ST, the combination of ST and PA yielded four categories: LST and VIPA (the reference category), LST and LMPA, HST and
VIPA, and HST and LMPA. 2.2. Assessment of perceived stress The Chinese Perceived Stress Scale (CPSS) (Cohen S et al., 1983), which has good reliability and validity among the general population of China (Yang TZ and Huang HT, 2003), was used to analyze perceived stress levels among college students during their daily study lives. The scale had 14 self-assessment items, with five answers per project, and adopted a 5-point (0 to 4) Likert grading method. The sum of each score was used as the stress scale score, which can range from 0 to 56 points. The total stress score indicated the level of stress each individual perceived, wherein a higher score suggested greater perceived stress. Considering previous research, showing that the ideal CPSS threshold score for stress among the general population is 25/26 (Yang TZ and Huang HT, 2003), total scores ≥26 and ≤25 were used to indicate high stress (coded as 1) and low stress (coded as 0), respectively. 2.3. Assessment of potential confounding factors Age, grade, specialization, home location, monthly living expenses, and sleep duration were considered potential confounding factors. Accordingly, grade was categorized as first, second, and third; specialization was categorized as clinical and non-clinical; home location was categorized as urban (in or from the city), town (larger than the countryside but smaller than the city), and rural (in or from the countryside); and monthly living expenses were categorized as ≤¥ 1000, ¥ 1001–1500, and ≥¥ 1501.
2.4. Statistical analysis Descriptive analyses were presented as means (standard deviation, SD) for continuous variables and numbers (percentages, %) for categorical variables. Differences in characteristics, by gender, were determined using the independent t-test for continuous variables and Pearson Chi-squared test for categorical variables. Differences in perceived stress among college students by gender, according to ST, PA, and a combination of both, were determined using the Pearson Chi-squared test. Independent and combined associations between ST and PA and perceived stress among college students by gender were determined using logistic regression models after adjusting for potential confounding factors, while odds ratios (OR) and their 95% confidence intervals (CI) were calculated. Statistical analysis was performed using the Statistical Package for the Social Sciences version 20.0, and statistical significance was set at P < 0.05. 3. Results 3.1. Student characteristics Table 1 presents the college students’ characteristics by gender. Overall, the students, 65.5% of whom were female, had an average age of 19.93 (1.07) years (range 17–23 years). Moreover, 52.3% reported LMPA, while 52.2% reported LST. Compared to female students, male students were older and had a higher prevalence of VIPA (age: P < 0.001; PA: P = 0.002). However, significant gender differences in other variables were not observed.
3.2. Distribution of perceived stress among the college students by gender Table 2 summarizes the distribution of perceived stress among college students by gender according to ST, PA, and the combination of ST and PA. Accordingly, more female students reporting HST experienced stress compared to those reporting LST (P = 0.001), while fewer female students reporting VIPA experienced stress compared to those reporting LMPA (P = 0.001). There was significant difference in the proportion of female students with perceived stress across the ST/PA categories (P < 0.001). After further pairwise comparisons (data not shown in the table), we found that more female students reporting both HST and LMPA experienced stress compared to those reporting both LST and VIPA (P < 0.001). However, proportional differences in perceived stress according to ST, PA, and the combination of ST and PA were not observed among male students. 3.3. Independent and combined associations between ST and PA and perceived stress among college students by gender Binary logistic regression was conducted to analyze independent associations between ST and PA and perceived stress after adjusting for potential confounding factors (Table 3). Among female students, those reporting HST (OR = 1.557, 95% CI = 1.129–2.145; P = 0.007) and LMPA (OR = 1.674, 95% CI = 1.204–2.329; P = 0.002) were more likely to experience stress. However, no significant independent associations between ST and PA and perceived stress were observed among male students.
Table 4 presents the OR for perceived stress by gender, according to combined ST and PA categories, determined using binary logistic regression after adjusting for potential confounding factors. Among female students, those reporting both LST and LMPA (OR = 2.174, 95% CI = 1.335–3.540; P = 0.002), both HST and VIPA (OR = 2.088, 95% CI = 1.250–3.490; P = 0.005), and both HST and LMPA (OR = 2.797, 95% CI = 1.747–4.477; P < 0.001) were more likely to experience stress compared to those reporting both LST and VIPA. However, there were no significant combined associations between ST and PA and perceived stress among male students. 4. Discussion After investigating independent and combined associations between ST and PA and perceived stress among college students, our findings indicated that, among female students, those reporting HST and LMPA were more likely to experience stress. Moreover, our results showed that the combined effects of PA and ST were significantly associated with perceived stress among females, but not males. The present study found that students with LMPA were more likely to experience stress. Regular PA has many beneficial effects for health, such as promoting cardiorespiratory fitness (Aires L et al., 2010) and reducing the risk of ischemic heart disease (Batty GD, 2002), stroke (Batty GD and Lee IM, 2002), diabetes (Jeon CY et al., 2007), and cognitive disorders (Larson et al., 2006). Several studies have also showed that PA was associated with stress. Indeed, Vankim and Nelson (2013) found that students who met vigorous PA recommendations were less likely to report poor
perceived stress, while Gerber et al. (2014) associated vigorous PA with lower stress among young adults. Another study also showed that regular exercise could protect against the negative emotional consequences of stress (Childs and de Wit, 2014). Possible explanations for PA’s effects on stress could include its beneficial effects on brain neurotransmitters, as well as on increasing levels of motivation and positive emotions, reducing stress and pain (Ekeland E et al., 2004; Paluska SA and Schwenk TL, 2000). Meanwhile, one survey observed a clear negative correlation between stress and sleep quality (Almojali AI et al., 2017). This association could be mediated by PA, given that exercise regulates temperature and improves sleep onset through vasodilation for peripheral heat dissipation (Driver HS and Taylor SR, 2000). Thus, PA can decrease stress and improve behavioral and emotional regulations by positively affecting sleep quality. The present study also revealed that participants with high ST were more likely to experience stress. The Academy of Pediatrics guidelines (2001) recommend that the ST of children and teenagers is not more than 2 h per day, but the median value for ST of college students was 6 h per day in our study, which was much higher than the recommendation for children and teenagers. Indeed, studies have shown that high ST was associated with poor health attributes, such as overweight and obesity (Lane et al., 2014), depression risk (Liu et al., 2015), and low self-esteem (Russ et al., 2009). Moreover, several studies had already indicated that increased self-reported use of electronic media was related to stress among young adults (Thomée et al., 2011) or females (Thomée et al., 2007). One study also found that increased use of information
and communication technology was associated with stress among young adults (Thomée et al., 2010), possibly because ST contributes to a sedentary lifestyle, which was highly correlated with stress. Accordingly, An et al. (2015) found that prolonged sedentary time was associated with risk for stress symptoms, and reducing sedentary behaviors could be one approach toward reducing perceived stress. Moreover, Trinh L et al. (2015) showed that high ST was associated with poor mental health, while Opoku-Acheampong et al. (2017) found that stress levels were negatively correlated with self-reported mental health. Furthermore, ST may consume time that could have otherwise been used for other activities. As such, spending more time on screen-based activities could lead to less time spent on sleep. Despite the aforementioned potential mechanisms explaining the association between ST and perceived stress, some uncertainty exists regarding the causal relationship between electronic media use and stress. Indeed, Caplan (2010) found that students with high levels of perceived stress might be more inclined to show increased media use as a form of avoidant coping. Therefore, further research is needed to determine whether ST and stress are interrelated or whether both factors accompany each other. The present study also investigated the association between the combined effects of PA and ST and perceived stress among college students. Accordingly, our results showed that students reporting both HST and LMPA, both HST and VIPA, and both LST and LMPA were more likely to experience stress. One possible underlying reason could be a potential threshold where sufficient time spent on high PA compensates for high ST. One study also negatively correlated high ST with vigorous
PA among females (Melkevik et al., 2010). Several studies had already confirmed that the combination of ST and PA had an impact on physical and psychological health. Accordingly, one study showed that Japanese adults with insufficient PA and high ST were significantly more likely to become overweight (Liao et al., 2011). Moreover, Feng et al. (2014) found that high PA and low ST could reduce the prevalence of depressive problems, while Wu et al. (2015) revealed that low PA and high ST could increase the risks of mental health problems and poor sleep quality. Similarly, the present study also confirmed that the combined effects of ST and PA influenced health. Thus, increasing PA among individuals with prolonged exposure to electronic media might be a suitable approach toward reducing the risk of perceived stress. The present study found the interactions between gender and the two exposures (ST and PA) in their association with perceived stress were not significant (P = 0.143 for PA × Gender and P = 0.440 for ST × Gender, data not shown in results), and the three way interaction (ST × PA × Gender) was also not significant (P = 0.787, data not shown in results). This implies that gender does not affect the associations of ST and PA with perceived stress. However, significant gender differences in the effects of PA and ST on perceived stress were still observed, with complex underlying reasons. One study indicated that significant interpersonal sensitivity was more frequently observed among female than male students (Nyström, M.B.T. et al., 2018). Moreover, Troisi (2001) found that females were more likely to feel the stressful effects of negative interpersonal events, while Van Wijk and Kolk (1997) showed that females might selectively pay attention to bodily cues and were more likely to report
the symptoms they perceive to others. Another study found that males were more likely to use active and instrumental coping behaviors, while females were more likely to use passive and emotionally focused behaviors (Ptacek et al., 1992). Matud (2004) also found that, compared to males, females believed their life events were more negative and less controllable, and that their coping style was more emotionally focused. These differences in stress perception and coping style between males and females may promote increased vulnerability of females to stress despite similar PA and electronic media exposure. Some study limitations should be considered. First, considering the cross-sectional design employed herein, we could not establish causal inferences from the associations between ST and PA and perceived stress. Second, samples from only one university, located in Shenyang, Northeast China, were included. Thus, our results cannot be generalized to all college students. Third, some variables, such as ST and PA, were assessed using a self-reported questionnaire, which might influence actual associations due to common method bias (Podsakoff, P. M. et al., 2003). Indeed, studies have shown that self-reported variables (Montag, C. et al., 2015), as well as self-report assessments of technology use, such as ST (Araujo, T. et al., 2017; Junco, R, 2013), are typically biased. Therefore, objective measurements, such as those obtained by tracking via applications, are needed in future studies. Finally, although we controlled for some confounding factors, we could not adjust for all possible related variables, such as psychological symptoms, health complaints and so on. Mood (2010) reported that Logistic regression estimates are affected by omitted
variables, even when these variables are unrelated to the independent variables in the model. Therefore, future studies should involve a more comprehensive set of covariates and make it as a strategy to obtain a clearer understanding of the effects of PA and ST on stress. 5. Conclusion The number of college students has been increasing worldwide. Considering that higher proportions of college students experience stress, which could considerably influence their lives and learning, reducing stress among students is imperative. The present study confirmed that LST and VIPA were independently and concurrently associated with significantly lower stress among college students, suggesting that promoting PA and reducing ST might be an effective approach toward reducing perceived stress among college students. Funding This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors. Acknowledgments The authors gratefully acknowledge the dedicated efforts of all the undergraduate volunteers and the great assistance of the staff members involved in this study. References Aires L, Andersen LB, Mendonca D, Martins C, Silva G, & Mota J. (2010). A 3-year
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Table 1 Characteristics of Chinese college students by gender a Male(n=392)
Female(n=745)
All(n=1137)
P
Age (years)
20.08,1.12
19.85,1.03
19.93,1.07
<0.001*
Sleep duration (h/day)
8.26,0.91
8.25,0.80
8.26,0.84
0.907
Mean (SD)
N (%) Grade
0.938 First
54(13.8)
99(13.3)
153(13.5)
Second
240(61.2)
465(62.4)
705(62.0)
Third
98(25.0)
181(24.3)
279(24.5)
specialization
0.831 Clinical
299(76.3)
564(75.7)
863(75.9)
Non-clinical
93(23.7)
181(24.3)
274(24.1)
Home location
0.643 Urban
220(56.1)
421(56.5)
641(56.4)
Town
84(21.4)
177(23.8)
261(23.0)
Rural
88(22.4)
147(19.7)
235(20.7)
Month living expenses
0.321
≤ ¥1,000
120(30.6)
212(28.5)
332(29.2)
¥1,001-1,500
191(48.7)
362(48.6)
553(48.6)
≥¥1,501
81(20.7)
171(23.0)
252(22.2)
ST b
0.076 ≤6 h/day
219(55.9)
375(50.3)
594(52.2)
>6h/day
173(44.1)
370(49.7)
543(47.8)
PA c
0.002* LMPA d
180(45.9)
415(55.7)
595(52.3)
VIPA e
212(54.1)
330(44.3)
542(47.7)
Perceived stress
a
0.750 Low
273(69.6)
512(68.7)
785(69.0)
High
119(30.4)
233(31.3)
352(31.0)
Values are presented as mean (SD) or N (%) when appropriate. b ST: screen time. c PA: physical activity. d LMPA:
light- and moderate-intensity physical activity. e VIPA: vigorous-intensity physical activity. *P<0.05.
Table 2 The distribution of different perceived stress among Chinese college students by gender according to ST, PA, and a combination of ST and PA group by using the Pearson Chi-squared test a Male
Female
Perceived stress Low (n=273)
High (n=119)
ST b
Perceived stress
X2
P
1.471
0.225
Low (n=512)
High (n=233)
≤6 h/day 158(72.1) 61(27.9)
278(74.1)
>6h/day 115(66.5) 58(33.5)
234(63.2) 136(36.8)
PA c
0.270
248(75.2)
0.001*
11.384
0.001*
2.968
20.916
<0.001*
82(24.8)
0.397
>6h/day and LMPA
51(62.2)
31(37.8)
134(60.4)
88(39.6)
>6h/day and VIPA
64(70.3)
27(29.7)
100(67.6)
48(32.4)
≤6 h/day and LMPA
72(73.5)
26(26.5)
130(67.4)
63(32.6)
≤6 h/day and VIPA
86(71.1)
35(28.9)
148(81.3)
34(18.7)
a
10.276
264(63.6) 151(36.4)
VIPA e 150(70.8) 62(29.2) ST/PA f
P
97(25.9)
0.603
LMPA d 123(68.3) 57(31.7)
X2
Values are presented as N (%). b ST: screen time. c PA: physical activity. d LMPA: light- and moderate-intensity
physical activity. e VIPA: vigorous-intensity physical activity. f ST/PA: a combination of screen time and physical activity. *P<0.05.
Table 3 Independent associations between screen time and physical activity and perceived stress among Chinese college students by gender a Male n(%)
Female
OR(95%CI)
P
n(%)
OR(95%CI)
P
ST b ≤6 h/day
219(55.9)
ref.
375(50.3) ref.
>6h/day
173(44.1)
1.275(0.814,1.996)
VIPA d
180(45.9)
ref.
LMPA e
212(54.1)
1.055(0.673,1.652)
0.288
370(49.7) 1.557(1.129,2.145)
0.007*
PA c
a
415(55.7) ref. 0.816
330(44.3) 1.674(1.204,2.329)
0.002*
Adjusted for age, grade, specialization, home location, monthly living expenses and sleep duration and also
adjusted for ST (for PA) or PA (for ST).
b
ST: screen time.
c
PA: physical activity. d VIPA: vigorous-intensity
physical activity. e LMPA: light- and moderate-intensity physical activity. *P<0.05.
Table 4 Combined associations between screen time and physical activity and perceived stress among Chinese college students by gender a Male n(%) ST/PA b
OR(95%CI)
Female P
n(%)
OR(95%CI)
P
≤6 h/day and VIPA c
121(30.9) ref.
≤6 h/day and LMPA d
98(25.0) 0.775(0.419,1.435)
0.418
193(25.9) 2.174(1.335,3.540)
0.002*
>6h/day and VIPA
91(23.2) 0.935(0.505,1.732)
0.832
148(19.9) 2.088(1.250,3.490)
0.005*
>6h/day and LMPA
82(20.9) 1.402(0.752,2.615)
0.288
222(29.8) 2.797(1.747,4.477)
<0.001*
a
182(24.4) ref.
Adjusted for age, grade, specialization, home location, monthly living expenses and sleep duration.
b
ST/PA: a
combination of screen time and physical activity. c VIPA: vigorous-intensity physical activity. d LMPA: light- and moderate-intensity physical activity. *P<0.05.
Highlights 1. Females reporting high screen time (HST, ST >6 h/day) were more likely to experience stress than those reporting low screen time (LST, ST ≤6 h/day). 2. Females reporting light- and moderate-intensity PA (LMPA) were more likely to experience stress than those reporting vigorous-intensity PA (VIPA). 3. Female reporting both LST and LMPA, both HST and VIPA, and both HST and LMPA were more likely to experience stress compared to those reporting both LST and VIPA.
Conflict of interest The authors declare that they have no competing interests.