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A review of literature relating to sleep in hospital with emphasis on the sleep of the ICU patient
Itlrnrrivc and Q Longman
CncicalCare Nursing Group UK
(1993) 9, 129-136 Ltd 1993
A review of literature relating to sleep in hospital with emphasis on the sleep of the ICU patient Alison M. Wood
The subject of this literature review is the sleep of hospitalised patients, with particular emphasis on the sleep of patients in intensive care units (ICUs). Initially there is an overview of the structure of sleep and the literature related to the main theories of sleep function in order to set the subject in context. A review of some of the work related to the sleep patterns of ICU patients outlines how severely sleep-deprived many patients are. Studies of sleep patterns implicate the environment of ICUs as an important factor in preventing sleep, but factors particular to patients which have an adverse effect on sleep are also reviewed, with particular reference to a study addressing the incidence of pain and discomfort of patients. Finally the sleep patterns of patients whose environment was carefully controlled to exclude factors known to disrupt sleep are reviewed. Thus the review moves from broad issues affecting sleep to the more focused issues personal to individual patients, with implications for nursing practice addressed as each point arises. In this way the complexity of the whole issue of sleep and the lack of sleep experienced by hospitalised patients is highlighted.
INTRODUCTION It is generally
agreed that sleep is important, in fact it has been claimed that lack of sleep can lead to death faster than lack of food (Carola et al, 1990). It has been noted that people under increased stress seem to require more sleep (McConigal, 1986). Being acutely ill is a stressor, as are the metabolic disturbances that accompany such illness, which implies that ICU AliaonM. Wood RGN, Nurse Teacher, Frances Harrison College of Health Care, Silverlands, Holloway Hill, Lyne, Chertsey, Surrey, UK (Requests for offprints to AW) Manuscript accepted 11 February 1992
patients in particular need more rest. However, McConigal (1986) found that hospital staff did not allow for the importance of sleep in planning care and were also lacking in knowledge about the process and function of sleep. This observation is supported by many studies, which have shown that lack of sleep among hospital patients is a problem, particularly in intensive care unit, (Closs, 1988). Sleep is a complex activity that can be affected by a large number of factors (Hobson, 1989), so it will not be possible to examine all of them. The main factors will be examined such as environment of care and certain patient factors that affect sleep. The importance of issues such as personal routines at bed time, the patient’s age 129
130
INTENSIVEANDCRITICALCARENURSING Waking
Stage one sleep
I
The eyes roll gently from side to side and the individual experiences a floating sensation. This stage is not classified as true sleep by many authors due to its transitory nature (about 5 min) and the ease with which the sleeper can be roused from this state.
7
NREM stage
/
1
stage 2 \
Stage two sleep
NREM
This is a slightly deeper stage of sleep, with the appearance of ‘sleep spindles’ on the EEG. Sleep is still not deep.
stage 3
NREM
NREM
stage 4
stage 2
NREM
/-
stage 3
An illustration of the cyclical nature of sleep. (NREM = non-rapid eye movement). Reproduced with permission from C.V. Mosby (Thelan, Davie & Urden, 1990). Fig.
and concurrent drug therapy are acknowledged but not examined here. It is hoped that this literature review will highlight for readers the importance of sleep, and the best way to promote it when planning care. The low priority given to this subject is reflected in the limited amount of nursing literature available on the subject (Webster & Thompson, 1986). In emphasising the importance of sleep, Adam and Oswald (1984) have said that there is an . . .’ obligation on all who work in hospitals to reduce noise, to relieve patients’ anxieties, and help them to sleep’.
Stage three sleep Slow breathing and pulse are accompanied by a decrease in temperature and blood pressure.
Stage four sleep This is the deepest sleep during which the pulse and breathing drop even further and the sleeper is difficult to rouse. Stages three and four constitute what is known as short wave sleep (SWS).
Rapid eye movement sleep (REM) Also referred to as paradoxical sleep, occurs during entry to each new sleep cycle. The eyes move rapidly, the rest of the body being profoundly relaxed, and dreaming occurs. This cycle is illustrated in the Figure.
THE FUNCTIONS
OF SLEEP
THE STRUCTURE OF SLEEP In order to meet the patient’s needs for sleep a knowledge of what it is would seem appropriate. By examining the EEG trace of a sleeping person it has been possible to classify different stages of sleep, according to the electrical activity of the brain. Carola et al (1990) describe these in the following way. The sleeper goes through these stages in cycles lasting about 90 min as follows:
The sleep wake cycle occurs over a period of approximately 24 h, although studies that have allowed people to ‘free run’, that is to sleep and wake at will while being cut off from external stimuli, demonstrate that humans have a cycle that is 25 hours in length (Gribben 1990). Sleep forms part of the circadian rhythm of the body which is accompanied by many bodily changes, such as variations in the levels of glucagon,
INTENSIVE
cortisol and catecholamines (Adam & Oswald, 1984) which inhibit protein synthesis and are at their highest during the day. During sleep the levels of growth hormone are increased, particularly in stage three and four sleep. This has led to the theory that wakefulness causes tissue catabolism and sleep induces anabolism (Adam 8c Oswald, 1984). In fact it is a traditionally held belief that sleep is necessary for healing (Webster & Thompson, 1986). Some authors dispute the tissue restitution theory, pointing out that although growth hormone levels are elevated during sleep, there is a corresponding reduction in the level of essential amino acids and insulin, both of which are needed for protein synthesis (Horne, 1983). Canavan (1984) quotes one theorist who claims that sleep is simply an instinct, a point of view which would suggest that sleep is not necessary at all. However, studies of sleep deprivation seem to contradict this idea, reporting physical and psychological symptoms in the subjects (Brewer, 1985). But many humans do live for years on a minimal amount of sleep with no apparent ill effect (Canavan, 1984), which has given support to the theory that a small amount of sleep is necessary, the remainder serving to conserve energy reserves and keep the sleeper safe (Horne, 1983). The fact that some sleep is essential to health, even though its functions are in dispute (Horne, 1983), would suggest that it is worthy of consideration in the planning of patient care. This is particularly relevant in the ICU where ‘ICU syndrome’ has been linked to sleep deprivation (Helton et al, 1980; McGonigal, 1986; Rainbow, 1989).
PATIENTS’ SLEEP PAlTERNS THE ICU
IN
Walker (1972) observed the amount of uninterrupted time available to patients during the first three days in the ICU following heart surgery. Her findings that patients were disturbed most frequently in the immediate postoperative period have been supported by other studies
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131
(Woods, 1972; Helton et al 1980). All the patients were disturbed at least once, and sometimes as often as 14 times per hour. Woods’ (1972) findings were broadly similar, her study revealing between 5 and 59 interruptions of sleep per eight-hour period. The small sample size of each study (4 in each case) is a limitation, as is the fact that neither researcher monitored the patients for more than 8 out of the 24 h at a time. Some authors have even sugggested that it is because of being on a by-pass machine during surgery that heart surgery patients are adversely affected by the ICU (Woods, 1972). If this is the case then any adverse effects suffered by this patient group can only be applied to the general patient population with caution. The presence of sleep was judged by observing the patient, a method which can be subjective and unreliable (Closs, 1988). Despite these factors, such studies are significant because they highlight the potential for extensive disruption of the ICU patients’ rest. Hilton (1976) also studied sleep patterns, but in a respiratory ICU. The patients were monitored polygraphically for 48 h continuously, thus providing a reliable record of sleep duration and depth (Closs, 1988). This study recognised the variability of sleep patterns between individuals (Webster 8c Thompson, 1986) by interviewing each patient after discharge from the ICU in order to enquire about their usual sleep pattern. The results reinforce Walker and Woods’ work by demonstrating greatly reduced sleep time, as little as 6min in 24 h in one patient. No complete sleep cycles were seen in any patient. Hilton’s work is limited by small sample size (10 patients). Although all were suffering from respiratory problems, their primary diagnosis varied. It has been suggested that the physiological state of the patient and his underlying illness may affect sleep patterns (Webster & Thompson 1986), consequently this introduces another variable and makes interpretation of the results more difficult. The implications of frequently disturbed sleep are significant, for although total sleep time may not be significantly reduced, the quality of sleep is affected (Canavan, 1986). Since one sleep cycle
132
INTENSIVE AND CRITICAL CARE NURSING
takes about 90min to complete (Carola et al, 1990) patients are being disturbed during the cycle, which requires them to start again at stage one following each interruption (McIntosh, 1989). This could lead to deprivation of sleep stages 3 and 4 or REM sleep. This was demonstrated in Hilton’s study in which patients sleep was predominantly stage 1. It is thought that stage 3 and 4 and REM sleep are the phases of sleep which offer the greatest restorative value to the individual (Carola et al, 1990). Consequently, the deprivation of these stages of sleep could have a detrimental effect on the health of the individual. When assessing a patient’s sleep nurses need to be aware of not just the apparent quantity of sleep obtained, but also the amount of disruption suffered by the patient. As Hilton (1976) has demonstrated, although one patient had as much as 13.3 h sleep in a 24h period, he still did not complete a single sleep cycle, and suffered poor quality sleep as a result. Hilton (1976) found that only half the sleep obtained by the patients in her study took place at night. This is probably explained by the findings of several studies (Bentley, 1977; Woods, 1972; Noble 1979), in which activity and noise were observed to continue around the clock in the ICU. This too has implications for patient care since the time of day has an effect on the quality of sleep obtained. Akerstedt and Gillberg (198 1) examined the effects of displacing sleep to various times of the day and night and found that sleep quality was at its best during the night. The study was conducted on healthy male volunteers in a sleep laboratory. This requires that the findings be applied cautiously to critically ill ICU patients. All potential disruptions to sleep were removed in Akerstedt and Gillberg’s study (1981), disproving the common belief that the larger number of disturbances present in the day time are the cause of poor quality day time sleep. Although limited by a small (6) sample size, this finding is significant since it suggests that sleep at night time will be of a better quality, due to its synchronisation with the normal circadian rhythm (Hobson, 1989). Therefore nurses should try to promote sleep at night, rather than
relying on extra day time rest, which is likely to be of inferior quality. Walker (1972) and Woods (1972) recorded the reasons why staff disturbed the patients’ rest and found that monitoring of the patients’ condition was the most common reason (Woods, 1972). Both authors recommend clustering nursing procedures and eliminating non-essential interventions during rest periods. Although sound advice, this on its own is not enough to assure the patient of an undisturbed night as it does not take account of the environment of the ICU, which has been found to be full of disturbing stimuli at all hours of the day and night (Noble, 1979). Both Walker and Woods acknowledge the part played by indirect stimuli in the ICU environment. The need to look at the problem in a broader way is illustrated by Hilton’s work (1976) which identified that even when no direct interruptions occurred the patients did not necessarily sleep.
THE ENVIRONMENT OF THE ICU Noble’s (1979) study of the environment of 4 ICUs included monitoring tactile, auditory and visual stimuli. Noble’s work was based on nonparticipant observation in 4 different ICUs, carried out on more than 50 occasions, each observation period being between 1 and 4 h in length. Observations were carried out at varying times of day. Thus Noble gained an overview of the environment of each unit over time. Although observation has been criticised as subjective (Closs, 1988), Noble attempted to address this by testing the validity and reliability of her findings. This was done by asking other nurse researchers to carry out further observations, the result of which supported her original findings. In addition to the numerous tactile stimuli noted in previous studies (Walker, 1972; Woods, 1972; Chilver, 1978), Noble (1979) also noted that lights were left on constantly. However, the most disturbing stimulus was the high noise level, the most conspicuous noises being caused by the staff talking. Rainbow (1989) describes
INTENSIVE AND CRITICAL CARE NURSING
problems such as sleep disturbances that can arise from sensory overload of the ICU patient. This may explain some of the sleeplessness of the patients in Hilton’s study. Bentley et al (1977) monitored the noise levels in an ICU and a ward using acoustic monitoring equipment, this being an objective measure of noise level, although limited since only one ICU was used. They were also able to monitor constantly for 5 days, thereby giving a complete picture of each day. They discovered noise levels were higher in the ICU than the ward at almost all times during the 24h period, and were generally due to noisy equipment and staff talking. At night these levels were well over the reommended maximum limit of 30 decibels, above which sleep tends to be disrupted (Bentley, 1977). The problem of sensory deprivation of ICU patients has been well documented (McGonigal, 1986), but these studies suggest that ICU patients are overloaded with stimuli. Noble’s observation that the staff seldom spoke to the patient, most of their communication being among themselves, suggests that patients were not receiving meaningful stimuli, but ajumble of staff conversations about work and personal matters. Noble concludes that this could be a source of confusion and anxiety to patients and may contribute to the development of ICU psychosis and stress, which has been linked to an increased mortality rate (Noble, 1979). The implications for nursing staff are great, since it is generally regarded as the nurses’ responsibility to provide an environment that will not be detrimental to the patient (Noble, 1979). Some of the peak noise levels measured with the audio equipment were due to machinery (Bentley et al, 1977), which is inescapable in the ICU. However, it is the human ear of the patient, with its attendant subjectivity, which is hearing the noise. Noble’s finding that the machine noises blended into the background because they were constant highlights the value of her work because of its subjectivity. She found intermittent noises far more noticeable, and these were usually due to staff talking. This is something which could be modified, for as Noble says, most staff seemed to be unaware of the ease
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with which their conversations could be overheard, and talked about personal problems within earshot of the researcher and patients. Some commands or requests were shouted alarmingly across the unit, and since anxiety is a factor in sleep deprivation (McGonigal, 1986) this could well have added to the patients’ problems. The extent to which the patients were concerned about the noises around them in Noble’s study is uncertain since she was not able to follow up many of the patients on discharge from the unit to interview them. Other studies (Jones et al, 1979), have found that patients are bothered by noise, implying that nurses need to be aware of the noise levels in the ICU. Some of these noises could be reduced immediately by pointing out to the staff that their communications can be disruptive (Noble, 1979). Although the design and layout of ICUs are not so amenable to change, noise ought to be considered in relation to them. Intensive care units are generally designed to allow staff to observe patients at all times (Noble, 1979). Perhaps this would still be possible if glass partitions were used.
PATIENT FACTORS AFFECTING SLEEP Many personal factors have been found to affect sleep including anxiety and pain (McGonigal, 1986) and drugs administered (Murphy et al, 1977). Jones et al (1979) interviewed 99 patients recently discharged from the ICU and found that sleep had been a problem for a quarter of them. The most common reasons given for difficulty in sleeping were inability to get into a comfortable position, pain and anxiety. This reinforces the findings of other studies (Murphy et al, 1977; Hilton 1976). Jones et al (1979) pointed out that the patients were grateful to the ICU staff for ‘making them better’. This highlights a possible shortcoming in the use of interviews with patients who have survived a critical illness; they may be reluctant to criticise the staff. The other problem with this approach was that approximately 50% of the
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INTENSIVEANDCRITICALCARENURSING
patients had some degree of memory impairment in relation to their time in the ICU, a finding that agrees with Noble’s observations. This is probably no bad thing, but as Jones et al (1979) discovered, many of the patients’ perceptions were inaccurate, e.g. whether relatives had visited them or not, if they had been ventilated or not and so on. It would be understandable if intubated patients in an ICU had difficulty expressing the need for analgesia. However, in a small report of a survey on sleep in hospitalised surgical patients, Murphy et al (1977) discovered sleep deprivation both before and after surgery. This limited report contains a significant finding from the nursing perspective; despite analgesics being prescribed, only two thirds of those who had surgery classified as ‘severe’ i.e. cholecystectomy, and one third of those having had ‘mild’ surgery such as herniorrhaphy, received intramuscular analgesia on the first night post-operatively. Pain was the reason given for lack of sleep along with noise in this study by Murphy et al (1979). It would seem from this that pain control was not given the priority that it should have received. These patients were all in a ward and therefore were presumably able to ask for analgesia. This problem was not investigated further by the researchers. Presumably the nursing staff either failed to recognise that patients were in pain or did not think it severe enough to warrant intramuscular analgesia. The high number of patients in pain and not given analgesia is something of which nurses need to be aware. Aurell and Elmqvist (1985) conducted a study of the sleep of 9 ICU patients following surgery. They were careful to control the environment so as to exclude factors known to be disturbing such as noise, light and frequent nursing interventions between 1 Ipm and 7am. Pain relief was given a priority and each patient was allocated a bed in a side room. In doing this the researchers believed that they had provided the optimal environment for sleep and rest. The patients were polygraphically monitored for the presence and quality of sleep continuously for 83 h. Since drug therapy can affect the normal structure of sleep (Webster & Thompson, 1986) the researchers were careful to exclude from the
study patients who had previously taken drugs that act on the central nervous system. They also documented the anaesthetic and analgesic drugs administered intra and post-operatively. The results of Aurell and Elmqvist’s work (1985) are interesting. Despite careful attention to all the environmental factors that could disturb sleep, the patients were all sleepdeprived. The average sleep time for the first 48h was 1 h 51 min. On the first night 5 of the patients did not sleep at all. Only 60% of the patients’ sleep occurred during the night, when optimal conditions for rest were supposed to prevail The sleep obtained was predominantly stage 1. This is similar to the findings in Hilton’s study in which patients in the usual ICU environment, with all its attendant disruptions, obtained only 50% of their sleep at night. Aurell and Elmqvist concluded that the effects of anaesthesia probably interfered with the wake/sleep regulating mechanism. Although the effects of anaesthesia may have been a contributory factor, anxiety would also seem to be a very likely component of the problem. The researchers considered this point and discounted it saying that all the patients seemed to adapt to the hospital environment well preoperatively and had denied being anxious prior to surgery, with 2 exceptions. The patients’ diagnoses were given in the paper, this reveals that 5 of them were having extensive surgery for a malignant disease and 2 of them for traumatic injuries. It could be argued that these represent stressful medical histories liable to cause the patient concern. If Aurell and Elmqvist had used a tool such as the Eysenck Personality Inventory, as used by Jones et al (1979), this issue could have been addressed more readily. Aurell and Elmqvist do not say if their patients received a visit from the ICU nurse preoperatively. This is a strategy often employed to reduce the patients’ anxiety (Jones et al 1979), for as Rainbow (1989) says, fear is often a large part of an ICU patient’s life. The effect that it may have on the patient’s sleep makes it an important factor for consideration when planning care. Another finding in Aurell and Elmqvist’s
INTENSIVE
study was that the nursing staff consistently over-estimated the amount of sleep obtained by each patient, implying that nurses are not aware how seriously sleep-deprived their patients may be. This indicates the importance of assessing the sleep of patients. This is currently based predominantly on each patient’s subjective report of the quality of his or her sleep and the nurses’ observations (Closs, 1988). Closs (1988) reported the inaccuracy often encountered in judging sleep by observation and cited a study by Dodds (1980) in which patients pretended to be asleep when the nurse came round in order not to create more work for the staff. Melzack and Wall (1988) have placed great emphasis on the importance of using an assessment tool for patients’ pain in order that it may be treated appropriately. Surely sleep, which like pain is also a subjective experience, should also be assessed in a more formal way than simply asking the patient if he or she has slept well.
CONCLUSION From this review of some of the published literature, it can be seen that hospital patients tend to be sleep-deprived (Woods, 1972; Walker, 1972; Hilton, 1976; Aurell and Elmqvist, 1985). The patients in ICUs seem to be particularly at risk of severe sleep deprivation due to the high level of activity in ICUs, which does not necessarily abate at night (Hilton, 1976). Despite the uncertainty surrounding the actual benefits of sleep, there can be no doubt that sleep is necessary for health (Hobson, 1989). Therefore it would be desirable if the nursing staff were to assess the environment of the ICU for known sleep-disturbing factors and minimise them at rest times. Although nurses have been found to acknowledge the importance of rest and sleep, they tend to disturb the patient around the clock in the ICU without consideration for the relative necessity of the tasks they carry out (Morgan & White, 1983). This suggests a lack of knowledge of the structure of sleep, i.e. that at least 90 minutes of uninterrupted sleep is needed to
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135
complete a cycle of sleep. An awareness of the structure of sleep would help nurses to plan their care in order to give patients the best chance of deriving maximum benefit from their rest. Another conclusion of this review is that sleep is affected by a number of interacting factors, and seems to require more than just the correct environment, this being difficult to obtain in a hospital. That patients are suffering pain and discomfort that inhibits their sleep is a reflection on the awareness of the nurses of their patients’ problems. Although individualised patient care is widely advocated, it does not appear to extend to the patients’ sleep patterns, despite the fact that they can be subject to considerable individual variation (Murphy et al, 1977). The observation of Murphy et al’s (1977) study that many patients were woken long before their normal time, because the hospital routine set the ‘lights on’ time, is a testament to the endurance of some aspects of the hospital routine. How much better it would be to enquire about individual sleep habits on admission in order to try and preserve the patients’ normal routine. Aurell and Elqvist’s (1985) discovery that the nurses greatly misjudged the quantity of the patients’ sleep suggests that nurses need to review how they assess a patient’s sleep. This is undoubtedly not easy since sleep and its quality is subjective and only really known to the sleeper himself. However, tools for assessing pain, another subjective sensation, have been developed. There would seem to be a place for a study to look at the development of a sleep assessment tool. Aurell and Elmqvist’s (1985) study demonstrates the complexity of the issue, and seems to suggest that for some patients sleep will never be easy, possibly due to the effect of drugs that may upset the sleep-regulating mechanism of the brain. But there are many things over which the nurses do have control such as environment, pain relief, psychological care to minimise anxiety and timing the implementation of nursing procedures and monitoring activities to minimise sleep disturbance. This seems particularly important in critical care areas where patients are the sickest in the hospital and yet may have the least opportunity to rest.
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References Adam K, Oswald I 1984 Sleep helps healing. British Medical Journal 289: 14Ot%1401 Akerstedt T, Gillberg M 198 1 The cicadian variation of experimentally displaced sleep. Sleep 4: 159-169 Aurell 1. Elmavist D 1985 Sleeu in the surgical intensive care&it: &ntinuous polygriphic recording of sleep in nine patients receiving postoperative care. British Medical Journal 290: 1029-1032 Bentley S, Murphy F, Dudley H 1977 Perceived noise in surgical wards and an intensive care area: an objective analysis. British Medical Journal 1503-1506 Brewer M 1985 To sleep or not to sleep: the consequences of sleep deprivation. Critical Care Nurse 5: 35 Canavan T 1984 The Psychobiology of sleep. Nursing 2(23): 682-683 Carola R, Harley J, Noback C 1990 Human anatomy and physiology. McGraw Hill. New York, p 73-77 Chilver W 1978 On being a patient in an intensive therapy unit. Nursing Mirror 146(14): 33-35 Closs J 1988 Assessment of Sleep in Hospital Patients. Journal of Advanced Nursing 13: 501-510 Dodds E 1980 Sleep well? A study of ward activity and nurse-patient interaction at night. MSc thesis (unpublished) University of Surrey Gribben M 1990 All in A Night’s Sleep. New Scientist l-4 Helton M, Cordon S, Nunnery S 1980 The Correlation Between Sleep Deprivation and the Intensive Care Unit Syndrome. Heart and Lung 9: 464-468 Hilton B 1976 Quantity and Quality of Sleep and Sleep Disturbing Factors in a Respiratory Intensive Care Unit. lournal of Advanced Nursing 1: 453-468
Hobson JA 1989 Sleep. Scientific American, New York, p 31-36 Horne J 1983 Human sleep and tissue restitution: Some qualifications and doubts. Clinical Science 65: 569578 Jones J, Hoggart B, Withey J, Donaghue K, Ellis B 1979 What the patients say: a Study of reactions to an intensive care unit. Intensive Care Medicine 5: 8%92 Melzack R, Wall P 1988 The challenge of pain 2nd Ed. Penguing Books, London McConinal K 1986 The lmwrtance of sleet and the sensory environment to c’ritically ill patients. Intensive Care Nursing 2: 73-83 McIntosh A 1989 Sleep Deprivation in critically ill Patients. Nursing 3: 44-45 Morgan H, White B 1983 Sleep deprivation. Nursing Mirror 157: S8-Sll Murphy F, Bentley S, Ellis B, Dudley H 1977 Sleep deprivation in patients undergoing operation: a factor in the stress of surgery. British Medical Journal 1521-1522 Rainbow C 1989 Monitoring the critically ill patient. Heinemann, London, p 182-I 88 Thelan L, Daine J, Urden L 1990 Textbook of critical care nursing: diagnosis and management. CV Mosby, St. Louis Walker B 1972 The post heart Surgery patient: amount of uninterrupted time for sleep and rest during the first, second, and third postoperative days in a teaching hospital. Nursing Research 21: 164-169 Webster R, Thompson D 1986 Sleep in hospital. Journal of Advanced Nursing 11 I447-457 Woods N 1972 Patterns of sleep in postcardiotomy Patients. Nursing Research 2 1: 347-352 ”
.
CncicalCare Nursing Group UK
(1993) 9, 129-136 Ltd 1993
A review of literature relating to sleep in hospital with emphasis on the sleep of the ICU patient Alison M. Wood
The subject of this literature review is the sleep of hospitalised patients, with particular emphasis on the sleep of patients in intensive care units (ICUs). Initially there is an overview of the structure of sleep and the literature related to the main theories of sleep function in order to set the subject in context. A review of some of the work related to the sleep patterns of ICU patients outlines how severely sleep-deprived many patients are. Studies of sleep patterns implicate the environment of ICUs as an important factor in preventing sleep, but factors particular to patients which have an adverse effect on sleep are also reviewed, with particular reference to a study addressing the incidence of pain and discomfort of patients. Finally the sleep patterns of patients whose environment was carefully controlled to exclude factors known to disrupt sleep are reviewed. Thus the review moves from broad issues affecting sleep to the more focused issues personal to individual patients, with implications for nursing practice addressed as each point arises. In this way the complexity of the whole issue of sleep and the lack of sleep experienced by hospitalised patients is highlighted.
INTRODUCTION It is generally
agreed that sleep is important, in fact it has been claimed that lack of sleep can lead to death faster than lack of food (Carola et al, 1990). It has been noted that people under increased stress seem to require more sleep (McConigal, 1986). Being acutely ill is a stressor, as are the metabolic disturbances that accompany such illness, which implies that ICU AliaonM. Wood RGN, Nurse Teacher, Frances Harrison College of Health Care, Silverlands, Holloway Hill, Lyne, Chertsey, Surrey, UK (Requests for offprints to AW) Manuscript accepted 11 February 1992
patients in particular need more rest. However, McConigal (1986) found that hospital staff did not allow for the importance of sleep in planning care and were also lacking in knowledge about the process and function of sleep. This observation is supported by many studies, which have shown that lack of sleep among hospital patients is a problem, particularly in intensive care unit, (Closs, 1988). Sleep is a complex activity that can be affected by a large number of factors (Hobson, 1989), so it will not be possible to examine all of them. The main factors will be examined such as environment of care and certain patient factors that affect sleep. The importance of issues such as personal routines at bed time, the patient’s age 129
130
INTENSIVEANDCRITICALCARENURSING Waking
Stage one sleep
I
The eyes roll gently from side to side and the individual experiences a floating sensation. This stage is not classified as true sleep by many authors due to its transitory nature (about 5 min) and the ease with which the sleeper can be roused from this state.
7
NREM stage
/
1
stage 2 \
Stage two sleep
NREM
This is a slightly deeper stage of sleep, with the appearance of ‘sleep spindles’ on the EEG. Sleep is still not deep.
stage 3
NREM
NREM
stage 4
stage 2
NREM
/-
stage 3
An illustration of the cyclical nature of sleep. (NREM = non-rapid eye movement). Reproduced with permission from C.V. Mosby (Thelan, Davie & Urden, 1990). Fig.
and concurrent drug therapy are acknowledged but not examined here. It is hoped that this literature review will highlight for readers the importance of sleep, and the best way to promote it when planning care. The low priority given to this subject is reflected in the limited amount of nursing literature available on the subject (Webster & Thompson, 1986). In emphasising the importance of sleep, Adam and Oswald (1984) have said that there is an . . .’ obligation on all who work in hospitals to reduce noise, to relieve patients’ anxieties, and help them to sleep’.
Stage three sleep Slow breathing and pulse are accompanied by a decrease in temperature and blood pressure.
Stage four sleep This is the deepest sleep during which the pulse and breathing drop even further and the sleeper is difficult to rouse. Stages three and four constitute what is known as short wave sleep (SWS).
Rapid eye movement sleep (REM) Also referred to as paradoxical sleep, occurs during entry to each new sleep cycle. The eyes move rapidly, the rest of the body being profoundly relaxed, and dreaming occurs. This cycle is illustrated in the Figure.
THE FUNCTIONS
OF SLEEP
THE STRUCTURE OF SLEEP In order to meet the patient’s needs for sleep a knowledge of what it is would seem appropriate. By examining the EEG trace of a sleeping person it has been possible to classify different stages of sleep, according to the electrical activity of the brain. Carola et al (1990) describe these in the following way. The sleeper goes through these stages in cycles lasting about 90 min as follows:
The sleep wake cycle occurs over a period of approximately 24 h, although studies that have allowed people to ‘free run’, that is to sleep and wake at will while being cut off from external stimuli, demonstrate that humans have a cycle that is 25 hours in length (Gribben 1990). Sleep forms part of the circadian rhythm of the body which is accompanied by many bodily changes, such as variations in the levels of glucagon,
INTENSIVE
cortisol and catecholamines (Adam & Oswald, 1984) which inhibit protein synthesis and are at their highest during the day. During sleep the levels of growth hormone are increased, particularly in stage three and four sleep. This has led to the theory that wakefulness causes tissue catabolism and sleep induces anabolism (Adam 8c Oswald, 1984). In fact it is a traditionally held belief that sleep is necessary for healing (Webster & Thompson, 1986). Some authors dispute the tissue restitution theory, pointing out that although growth hormone levels are elevated during sleep, there is a corresponding reduction in the level of essential amino acids and insulin, both of which are needed for protein synthesis (Horne, 1983). Canavan (1984) quotes one theorist who claims that sleep is simply an instinct, a point of view which would suggest that sleep is not necessary at all. However, studies of sleep deprivation seem to contradict this idea, reporting physical and psychological symptoms in the subjects (Brewer, 1985). But many humans do live for years on a minimal amount of sleep with no apparent ill effect (Canavan, 1984), which has given support to the theory that a small amount of sleep is necessary, the remainder serving to conserve energy reserves and keep the sleeper safe (Horne, 1983). The fact that some sleep is essential to health, even though its functions are in dispute (Horne, 1983), would suggest that it is worthy of consideration in the planning of patient care. This is particularly relevant in the ICU where ‘ICU syndrome’ has been linked to sleep deprivation (Helton et al, 1980; McGonigal, 1986; Rainbow, 1989).
PATIENTS’ SLEEP PAlTERNS THE ICU
IN
Walker (1972) observed the amount of uninterrupted time available to patients during the first three days in the ICU following heart surgery. Her findings that patients were disturbed most frequently in the immediate postoperative period have been supported by other studies
AND CRITICAL
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(Woods, 1972; Helton et al 1980). All the patients were disturbed at least once, and sometimes as often as 14 times per hour. Woods’ (1972) findings were broadly similar, her study revealing between 5 and 59 interruptions of sleep per eight-hour period. The small sample size of each study (4 in each case) is a limitation, as is the fact that neither researcher monitored the patients for more than 8 out of the 24 h at a time. Some authors have even sugggested that it is because of being on a by-pass machine during surgery that heart surgery patients are adversely affected by the ICU (Woods, 1972). If this is the case then any adverse effects suffered by this patient group can only be applied to the general patient population with caution. The presence of sleep was judged by observing the patient, a method which can be subjective and unreliable (Closs, 1988). Despite these factors, such studies are significant because they highlight the potential for extensive disruption of the ICU patients’ rest. Hilton (1976) also studied sleep patterns, but in a respiratory ICU. The patients were monitored polygraphically for 48 h continuously, thus providing a reliable record of sleep duration and depth (Closs, 1988). This study recognised the variability of sleep patterns between individuals (Webster 8c Thompson, 1986) by interviewing each patient after discharge from the ICU in order to enquire about their usual sleep pattern. The results reinforce Walker and Woods’ work by demonstrating greatly reduced sleep time, as little as 6min in 24 h in one patient. No complete sleep cycles were seen in any patient. Hilton’s work is limited by small sample size (10 patients). Although all were suffering from respiratory problems, their primary diagnosis varied. It has been suggested that the physiological state of the patient and his underlying illness may affect sleep patterns (Webster & Thompson 1986), consequently this introduces another variable and makes interpretation of the results more difficult. The implications of frequently disturbed sleep are significant, for although total sleep time may not be significantly reduced, the quality of sleep is affected (Canavan, 1986). Since one sleep cycle
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takes about 90min to complete (Carola et al, 1990) patients are being disturbed during the cycle, which requires them to start again at stage one following each interruption (McIntosh, 1989). This could lead to deprivation of sleep stages 3 and 4 or REM sleep. This was demonstrated in Hilton’s study in which patients sleep was predominantly stage 1. It is thought that stage 3 and 4 and REM sleep are the phases of sleep which offer the greatest restorative value to the individual (Carola et al, 1990). Consequently, the deprivation of these stages of sleep could have a detrimental effect on the health of the individual. When assessing a patient’s sleep nurses need to be aware of not just the apparent quantity of sleep obtained, but also the amount of disruption suffered by the patient. As Hilton (1976) has demonstrated, although one patient had as much as 13.3 h sleep in a 24h period, he still did not complete a single sleep cycle, and suffered poor quality sleep as a result. Hilton (1976) found that only half the sleep obtained by the patients in her study took place at night. This is probably explained by the findings of several studies (Bentley, 1977; Woods, 1972; Noble 1979), in which activity and noise were observed to continue around the clock in the ICU. This too has implications for patient care since the time of day has an effect on the quality of sleep obtained. Akerstedt and Gillberg (198 1) examined the effects of displacing sleep to various times of the day and night and found that sleep quality was at its best during the night. The study was conducted on healthy male volunteers in a sleep laboratory. This requires that the findings be applied cautiously to critically ill ICU patients. All potential disruptions to sleep were removed in Akerstedt and Gillberg’s study (1981), disproving the common belief that the larger number of disturbances present in the day time are the cause of poor quality day time sleep. Although limited by a small (6) sample size, this finding is significant since it suggests that sleep at night time will be of a better quality, due to its synchronisation with the normal circadian rhythm (Hobson, 1989). Therefore nurses should try to promote sleep at night, rather than
relying on extra day time rest, which is likely to be of inferior quality. Walker (1972) and Woods (1972) recorded the reasons why staff disturbed the patients’ rest and found that monitoring of the patients’ condition was the most common reason (Woods, 1972). Both authors recommend clustering nursing procedures and eliminating non-essential interventions during rest periods. Although sound advice, this on its own is not enough to assure the patient of an undisturbed night as it does not take account of the environment of the ICU, which has been found to be full of disturbing stimuli at all hours of the day and night (Noble, 1979). Both Walker and Woods acknowledge the part played by indirect stimuli in the ICU environment. The need to look at the problem in a broader way is illustrated by Hilton’s work (1976) which identified that even when no direct interruptions occurred the patients did not necessarily sleep.
THE ENVIRONMENT OF THE ICU Noble’s (1979) study of the environment of 4 ICUs included monitoring tactile, auditory and visual stimuli. Noble’s work was based on nonparticipant observation in 4 different ICUs, carried out on more than 50 occasions, each observation period being between 1 and 4 h in length. Observations were carried out at varying times of day. Thus Noble gained an overview of the environment of each unit over time. Although observation has been criticised as subjective (Closs, 1988), Noble attempted to address this by testing the validity and reliability of her findings. This was done by asking other nurse researchers to carry out further observations, the result of which supported her original findings. In addition to the numerous tactile stimuli noted in previous studies (Walker, 1972; Woods, 1972; Chilver, 1978), Noble (1979) also noted that lights were left on constantly. However, the most disturbing stimulus was the high noise level, the most conspicuous noises being caused by the staff talking. Rainbow (1989) describes
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problems such as sleep disturbances that can arise from sensory overload of the ICU patient. This may explain some of the sleeplessness of the patients in Hilton’s study. Bentley et al (1977) monitored the noise levels in an ICU and a ward using acoustic monitoring equipment, this being an objective measure of noise level, although limited since only one ICU was used. They were also able to monitor constantly for 5 days, thereby giving a complete picture of each day. They discovered noise levels were higher in the ICU than the ward at almost all times during the 24h period, and were generally due to noisy equipment and staff talking. At night these levels were well over the reommended maximum limit of 30 decibels, above which sleep tends to be disrupted (Bentley, 1977). The problem of sensory deprivation of ICU patients has been well documented (McGonigal, 1986), but these studies suggest that ICU patients are overloaded with stimuli. Noble’s observation that the staff seldom spoke to the patient, most of their communication being among themselves, suggests that patients were not receiving meaningful stimuli, but ajumble of staff conversations about work and personal matters. Noble concludes that this could be a source of confusion and anxiety to patients and may contribute to the development of ICU psychosis and stress, which has been linked to an increased mortality rate (Noble, 1979). The implications for nursing staff are great, since it is generally regarded as the nurses’ responsibility to provide an environment that will not be detrimental to the patient (Noble, 1979). Some of the peak noise levels measured with the audio equipment were due to machinery (Bentley et al, 1977), which is inescapable in the ICU. However, it is the human ear of the patient, with its attendant subjectivity, which is hearing the noise. Noble’s finding that the machine noises blended into the background because they were constant highlights the value of her work because of its subjectivity. She found intermittent noises far more noticeable, and these were usually due to staff talking. This is something which could be modified, for as Noble says, most staff seemed to be unaware of the ease
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with which their conversations could be overheard, and talked about personal problems within earshot of the researcher and patients. Some commands or requests were shouted alarmingly across the unit, and since anxiety is a factor in sleep deprivation (McGonigal, 1986) this could well have added to the patients’ problems. The extent to which the patients were concerned about the noises around them in Noble’s study is uncertain since she was not able to follow up many of the patients on discharge from the unit to interview them. Other studies (Jones et al, 1979), have found that patients are bothered by noise, implying that nurses need to be aware of the noise levels in the ICU. Some of these noises could be reduced immediately by pointing out to the staff that their communications can be disruptive (Noble, 1979). Although the design and layout of ICUs are not so amenable to change, noise ought to be considered in relation to them. Intensive care units are generally designed to allow staff to observe patients at all times (Noble, 1979). Perhaps this would still be possible if glass partitions were used.
PATIENT FACTORS AFFECTING SLEEP Many personal factors have been found to affect sleep including anxiety and pain (McGonigal, 1986) and drugs administered (Murphy et al, 1977). Jones et al (1979) interviewed 99 patients recently discharged from the ICU and found that sleep had been a problem for a quarter of them. The most common reasons given for difficulty in sleeping were inability to get into a comfortable position, pain and anxiety. This reinforces the findings of other studies (Murphy et al, 1977; Hilton 1976). Jones et al (1979) pointed out that the patients were grateful to the ICU staff for ‘making them better’. This highlights a possible shortcoming in the use of interviews with patients who have survived a critical illness; they may be reluctant to criticise the staff. The other problem with this approach was that approximately 50% of the
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patients had some degree of memory impairment in relation to their time in the ICU, a finding that agrees with Noble’s observations. This is probably no bad thing, but as Jones et al (1979) discovered, many of the patients’ perceptions were inaccurate, e.g. whether relatives had visited them or not, if they had been ventilated or not and so on. It would be understandable if intubated patients in an ICU had difficulty expressing the need for analgesia. However, in a small report of a survey on sleep in hospitalised surgical patients, Murphy et al (1977) discovered sleep deprivation both before and after surgery. This limited report contains a significant finding from the nursing perspective; despite analgesics being prescribed, only two thirds of those who had surgery classified as ‘severe’ i.e. cholecystectomy, and one third of those having had ‘mild’ surgery such as herniorrhaphy, received intramuscular analgesia on the first night post-operatively. Pain was the reason given for lack of sleep along with noise in this study by Murphy et al (1979). It would seem from this that pain control was not given the priority that it should have received. These patients were all in a ward and therefore were presumably able to ask for analgesia. This problem was not investigated further by the researchers. Presumably the nursing staff either failed to recognise that patients were in pain or did not think it severe enough to warrant intramuscular analgesia. The high number of patients in pain and not given analgesia is something of which nurses need to be aware. Aurell and Elmqvist (1985) conducted a study of the sleep of 9 ICU patients following surgery. They were careful to control the environment so as to exclude factors known to be disturbing such as noise, light and frequent nursing interventions between 1 Ipm and 7am. Pain relief was given a priority and each patient was allocated a bed in a side room. In doing this the researchers believed that they had provided the optimal environment for sleep and rest. The patients were polygraphically monitored for the presence and quality of sleep continuously for 83 h. Since drug therapy can affect the normal structure of sleep (Webster & Thompson, 1986) the researchers were careful to exclude from the
study patients who had previously taken drugs that act on the central nervous system. They also documented the anaesthetic and analgesic drugs administered intra and post-operatively. The results of Aurell and Elmqvist’s work (1985) are interesting. Despite careful attention to all the environmental factors that could disturb sleep, the patients were all sleepdeprived. The average sleep time for the first 48h was 1 h 51 min. On the first night 5 of the patients did not sleep at all. Only 60% of the patients’ sleep occurred during the night, when optimal conditions for rest were supposed to prevail The sleep obtained was predominantly stage 1. This is similar to the findings in Hilton’s study in which patients in the usual ICU environment, with all its attendant disruptions, obtained only 50% of their sleep at night. Aurell and Elmqvist concluded that the effects of anaesthesia probably interfered with the wake/sleep regulating mechanism. Although the effects of anaesthesia may have been a contributory factor, anxiety would also seem to be a very likely component of the problem. The researchers considered this point and discounted it saying that all the patients seemed to adapt to the hospital environment well preoperatively and had denied being anxious prior to surgery, with 2 exceptions. The patients’ diagnoses were given in the paper, this reveals that 5 of them were having extensive surgery for a malignant disease and 2 of them for traumatic injuries. It could be argued that these represent stressful medical histories liable to cause the patient concern. If Aurell and Elmqvist had used a tool such as the Eysenck Personality Inventory, as used by Jones et al (1979), this issue could have been addressed more readily. Aurell and Elmqvist do not say if their patients received a visit from the ICU nurse preoperatively. This is a strategy often employed to reduce the patients’ anxiety (Jones et al 1979), for as Rainbow (1989) says, fear is often a large part of an ICU patient’s life. The effect that it may have on the patient’s sleep makes it an important factor for consideration when planning care. Another finding in Aurell and Elmqvist’s
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study was that the nursing staff consistently over-estimated the amount of sleep obtained by each patient, implying that nurses are not aware how seriously sleep-deprived their patients may be. This indicates the importance of assessing the sleep of patients. This is currently based predominantly on each patient’s subjective report of the quality of his or her sleep and the nurses’ observations (Closs, 1988). Closs (1988) reported the inaccuracy often encountered in judging sleep by observation and cited a study by Dodds (1980) in which patients pretended to be asleep when the nurse came round in order not to create more work for the staff. Melzack and Wall (1988) have placed great emphasis on the importance of using an assessment tool for patients’ pain in order that it may be treated appropriately. Surely sleep, which like pain is also a subjective experience, should also be assessed in a more formal way than simply asking the patient if he or she has slept well.
CONCLUSION From this review of some of the published literature, it can be seen that hospital patients tend to be sleep-deprived (Woods, 1972; Walker, 1972; Hilton, 1976; Aurell and Elmqvist, 1985). The patients in ICUs seem to be particularly at risk of severe sleep deprivation due to the high level of activity in ICUs, which does not necessarily abate at night (Hilton, 1976). Despite the uncertainty surrounding the actual benefits of sleep, there can be no doubt that sleep is necessary for health (Hobson, 1989). Therefore it would be desirable if the nursing staff were to assess the environment of the ICU for known sleep-disturbing factors and minimise them at rest times. Although nurses have been found to acknowledge the importance of rest and sleep, they tend to disturb the patient around the clock in the ICU without consideration for the relative necessity of the tasks they carry out (Morgan & White, 1983). This suggests a lack of knowledge of the structure of sleep, i.e. that at least 90 minutes of uninterrupted sleep is needed to
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complete a cycle of sleep. An awareness of the structure of sleep would help nurses to plan their care in order to give patients the best chance of deriving maximum benefit from their rest. Another conclusion of this review is that sleep is affected by a number of interacting factors, and seems to require more than just the correct environment, this being difficult to obtain in a hospital. That patients are suffering pain and discomfort that inhibits their sleep is a reflection on the awareness of the nurses of their patients’ problems. Although individualised patient care is widely advocated, it does not appear to extend to the patients’ sleep patterns, despite the fact that they can be subject to considerable individual variation (Murphy et al, 1977). The observation of Murphy et al’s (1977) study that many patients were woken long before their normal time, because the hospital routine set the ‘lights on’ time, is a testament to the endurance of some aspects of the hospital routine. How much better it would be to enquire about individual sleep habits on admission in order to try and preserve the patients’ normal routine. Aurell and Elqvist’s (1985) discovery that the nurses greatly misjudged the quantity of the patients’ sleep suggests that nurses need to review how they assess a patient’s sleep. This is undoubtedly not easy since sleep and its quality is subjective and only really known to the sleeper himself. However, tools for assessing pain, another subjective sensation, have been developed. There would seem to be a place for a study to look at the development of a sleep assessment tool. Aurell and Elmqvist’s (1985) study demonstrates the complexity of the issue, and seems to suggest that for some patients sleep will never be easy, possibly due to the effect of drugs that may upset the sleep-regulating mechanism of the brain. But there are many things over which the nurses do have control such as environment, pain relief, psychological care to minimise anxiety and timing the implementation of nursing procedures and monitoring activities to minimise sleep disturbance. This seems particularly important in critical care areas where patients are the sickest in the hospital and yet may have the least opportunity to rest.
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References Adam K, Oswald I 1984 Sleep helps healing. British Medical Journal 289: 14Ot%1401 Akerstedt T, Gillberg M 198 1 The cicadian variation of experimentally displaced sleep. Sleep 4: 159-169 Aurell 1. Elmavist D 1985 Sleeu in the surgical intensive care&it: &ntinuous polygriphic recording of sleep in nine patients receiving postoperative care. British Medical Journal 290: 1029-1032 Bentley S, Murphy F, Dudley H 1977 Perceived noise in surgical wards and an intensive care area: an objective analysis. British Medical Journal 1503-1506 Brewer M 1985 To sleep or not to sleep: the consequences of sleep deprivation. Critical Care Nurse 5: 35 Canavan T 1984 The Psychobiology of sleep. Nursing 2(23): 682-683 Carola R, Harley J, Noback C 1990 Human anatomy and physiology. McGraw Hill. New York, p 73-77 Chilver W 1978 On being a patient in an intensive therapy unit. Nursing Mirror 146(14): 33-35 Closs J 1988 Assessment of Sleep in Hospital Patients. Journal of Advanced Nursing 13: 501-510 Dodds E 1980 Sleep well? A study of ward activity and nurse-patient interaction at night. MSc thesis (unpublished) University of Surrey Gribben M 1990 All in A Night’s Sleep. New Scientist l-4 Helton M, Cordon S, Nunnery S 1980 The Correlation Between Sleep Deprivation and the Intensive Care Unit Syndrome. Heart and Lung 9: 464-468 Hilton B 1976 Quantity and Quality of Sleep and Sleep Disturbing Factors in a Respiratory Intensive Care Unit. lournal of Advanced Nursing 1: 453-468
Hobson JA 1989 Sleep. Scientific American, New York, p 31-36 Horne J 1983 Human sleep and tissue restitution: Some qualifications and doubts. Clinical Science 65: 569578 Jones J, Hoggart B, Withey J, Donaghue K, Ellis B 1979 What the patients say: a Study of reactions to an intensive care unit. Intensive Care Medicine 5: 8%92 Melzack R, Wall P 1988 The challenge of pain 2nd Ed. Penguing Books, London McConinal K 1986 The lmwrtance of sleet and the sensory environment to c’ritically ill patients. Intensive Care Nursing 2: 73-83 McIntosh A 1989 Sleep Deprivation in critically ill Patients. Nursing 3: 44-45 Morgan H, White B 1983 Sleep deprivation. Nursing Mirror 157: S8-Sll Murphy F, Bentley S, Ellis B, Dudley H 1977 Sleep deprivation in patients undergoing operation: a factor in the stress of surgery. British Medical Journal 1521-1522 Rainbow C 1989 Monitoring the critically ill patient. Heinemann, London, p 182-I 88 Thelan L, Daine J, Urden L 1990 Textbook of critical care nursing: diagnosis and management. CV Mosby, St. Louis Walker B 1972 The post heart Surgery patient: amount of uninterrupted time for sleep and rest during the first, second, and third postoperative days in a teaching hospital. Nursing Research 21: 164-169 Webster R, Thompson D 1986 Sleep in hospital. Journal of Advanced Nursing 11 I447-457 Woods N 1972 Patterns of sleep in postcardiotomy Patients. Nursing Research 2 1: 347-352 ”
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