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The Importance of Good Sleep in the ICU

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Mary Ann Barnes-Daly, MS, RN, CCRN-K, DC
Madison L. Fratzke, BSRT, RRT-ACCS
Kimia Honarmand, BSc(Hons), MSc, MD, FRCPC
Paula L. Watson, MD

Critically ill patients commonly experience severe sleep disruption and deprivation. Excessive sleep fragmentation, reduced REM sleep, and loss of normal circadian rhythm are common. Atypical sleep (characterized by δ waves without cyclic organization and by the absence of K complexes and sleep spindles) and pathologic wakefulness (δ and Θ waves in behaviorally awake patients) may be present.1-3 The causes of poor sleep quality and atypical sleep are multifactorial and include the patient’s underlying illness, pain, the intensive care unit (ICU) environment, and medications.
Poor sleep can adversely affect patients’ psychological well-being. ICU patients rank sleep disruptions as one of the chief causes of distress during their ICU stay.4,5 Poor sleep quality is not only a significant cause of emotional distress but has also been hypothesized to contribute to cognitive dysfunction, ICU delirium, impaired immune function, and prolonged mechanical ventilation.
Inadequate sleep can cause decreased attention and impaired psychomotor performance and likely contributes to the neurocognitive dysfunction common in critically ill patients. Sleep deprivation and ICU delirium frequently coexist in ICU patients, but a causal relationship has not been established. Critically ill patients with severe sleep deprivation are more likely to have mental status changes.6-8 Also, circadian sleep-cycle disturbance and severe reduction in REM sleep have been associated with an increase in ICU delirium.7,8
The effect of sleep deprivation on the immune system has not been studied in the ICU population. In healthy people, the effect can vary depending on whether the sleep deprivation is acute or chronic. Abnormalities in T helper and NK cell number and their functions have been noted—effects that, if present in ICU patients, would have potential clinical implications.9,10 Proinflammatory cytokines, TNF-α and IL-6, are increased in association with poor sleep quality.11 Both total and partial sleep deprivation are associated with increased C-reactive protein levels in healthy volunteers.12 Abnormalities in cellular metabolism, nitrogen balance, and glucose metabolism have also been described in sleep-deprived patients.
Sleep affects respiratory physiology. During sleep, oxygen consumption and carbon dioxide production both decrease, leading to a physiologic reduction in necessary ventilation. Early studies have shown that sleep deprivation decreases the ventilatory response to both carbon dioxide and hypoxia13 and causes a decrease in respiratory muscle endurance.14 These findings led to the hypothesis that poor sleep may prolong duration on mechanical ventilation.
While data on the effect of sleep quality on respiratory outcomes of ICU patients is limited, a few studies deserve mention. Roche-Campo et al found that patients with abnormal sleep (characterized by increased daytime sleep and reduced REM) were more likely to fail noninvasive ventilation and require intubation and mechanical ventilation.8 Chen et al showed that sleep quality, as measured by the Verran and Snyder-Halpern Sleep Scale questionnaire, is associated with successful weaning from mechanical ventilation.15 The presence of atypical sleep and the absence of REM sleep have also been associated with a longer duration of weaning from mechanical ventilation.16,17 Further study is needed to determine whether there is a causal relationship between sleep quality and duration of mechanical ventilation.
As a potentially modifiable risk factor influencing both the emotional well-being and the physical recovery of critically ill patients, sleep deserves attention. Promoting good sleep quality should be regarded as an essential component to the adequate care of critically ill patients.
What are common barriers to implementing a good sleep program in the ICU?
Factors that may affect patients’ ability to experience adequate sleep in the ICU, meaning both quality and quantity, are multifactorial. The nature of the underlying illness may be an unmodifiable factor, whereas the experience and treatment of pain, medication choice, and especially the ICU environment and care routines must be considered when the focus is patient comfort and good sleep. Before the publication of the Clinical Practice Guidelines for the Prevention and Management of Pain, Agitation/Sedation, Delirium, Immobility, and Sleep Disruption in Adult Patients in the ICU (PADIS),18 the quality and quantity of sleep were not emphasized as important considerations in patient care planning. Accepting this new focus may be difficult for clinicians who are struggling with varied clinical priorities, and poor sleep in the ICU may be a forgone conclusion.
Before the PADIS guidelines were introduced, assessing the patient’s home sleep patterns and preferences and performing a daily sleep assessment each morning were not standards of care, so attention to sleep quality and quantity were not addressed. The ICU Liberation Initiative is considering adding “good sleep” to the ICU Liberation bundle (A-F).
The critical care patient’s underlying illness is typically accompanied by stress and immune/inflammatory responses. Combined with a high likelihood of ICU delirium, this creates internal factors that affect sleep. The environment in the ICU patient’s room and in the unit is not typical of the type of sleep environment that the patient experiences at home and is therefore not conducive to good sleep. Unfamiliar and excessive noises and lights make for frequent disturbances during all times of the day, with an especially large impact during normal sleeping hours.19 Patient-ventilator interactions and the typical need for frequent bedside assessments and interventions all combine to limit the length of sleep periods. The performance of assessments and other bedside care tasks as a matter of rote or according to unit culture, rather than specific to each patient’s need, may result in frequent and perhaps unnecessary disturbances during normal sleep hours. For example, standing unit policies related to vital sign and pain assessments and specific types of assessments, such as those for neurologic function, may require hourly awakenings that preclude protected sleep periods.
Undetected or inadequately managed pain in the ICU environment can also be a cause of interrupted sleep.20,21 Finally, the use of sedative medications, particularly at night, reduces slow-wave and REM sleep, both of which are the most restorative.22
How can ICU teams help promote sleep in the ICU?

It is important to recognize that the causes of sleep disruption in ICU patients are multifactorial and vary among patients and even within the same patient at various times in their illness trajectory. Because of this, there is no singular approach to improving sleep quality in ICU patients. Instead, clinicians are encouraged to recognize the potential factors that may contribute to sleep disruption and implement individualized approaches to minimize their impact on sleep quality.
First, clinicians are encouraged to recognize that some ICU patients are inherently more susceptible to sleep disruption than others and to identify patients at particularly high risk for sleep disruption in ICU. Patients who have poor sleep quality at home are more susceptible to sleep disruption in the ICU.23,24 Because of this, clinicians are encouraged to elicit (from the patient when possible and always by engaging the patient’s family) and document sleep history, including diagnosed or suspected sleep disorders, sleep habits, and use of sleep aids prior to ICU admission.
Clinicians are encouraged to recognize the physiologic and psychological factors that may adversely affect sleep quality in ICU patients. For example, pain is common in ICU patients and has been linked to disrupted sleep in the ICU.25-27 Proactively assessing for signs of pain and promptly treating pain when detected using the principles outlined in the ICU Liberation bundle (A-F) may improve sleep quality in ICU patients.28 Other disease-specific physiologic symptoms such as dyspnea or nausea may have similar effects on sleep quality, and their proactive management may improve sleep quality in the ICU. Delirium has been associated with poor sleep in ICU patients.7,29 Clinicians are encouraged to actively screen for signs of delirium and implement nonpharmacologic strategies to reduce the risk of delirium and both nonpharmacologic and pharmacologic therapies to treat delirium in ICU patients.
A variety of factors related to the ICU environment and interventions may have a significant impact on sleep quality in ICU patients (Table 1). Care activities,25,26,30 attachment to medical devices,25,26 noise,25,27,30 light ,25-27,30 and patient-ventilator asynchrony31,32 may worsen sleep quality in ICU patients. Clinicians may implement strategies to minimize the impact of these factors on sleep quality. Table 1 provides recommendations for reducing the impact of the ICU environment on sleep quality.
Given the complex interactions between various intrinsic and extrinsic factors that influence sleep quality in ICU patients, unit-wide implementation of a specific sleep policies should be complemented with management strategies that are individualized to each patient’s needs. It is advisable that, such policies focus on routinely eliciting and documenting a sleep history and routine monitoring of clinical signs of physiologic and psychological causes of sleep disruption rather than protocols that prescribe nonpersonalized, unit-wide interventions.
What role, if any, can families play in helping to promote good sleep?
The effect families have on patients achieving good sleep in the ICU is not well studied. Families could be more involved in the clustered care method33 by coordinating visitation based on the sleep plan developed by the care team. If a patient cannot provide his/her own history, families could be invited to provide information on the patient’s normal sleep routine. Furthermore, families may influence patients’ stress and anxiety levels, which are factors that have been identified as possibly affecting good sleep.34,35 Every family is different and should be educated on the importance of good sleep to help improve compliance and awareness. These areas need further investigation to evaluate the effect families have on patients achieving good sleep.


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