By James McFeely, MD
Medical Director, Critical Care Units, Alta Bates Summit Medical Center, Berkeley, CA
Dr. McFeely reports no financial relationships relevant to this field of study.
Lack of quality sleep is a ubiquitous problem for ICU patients. Recent recognition of the importance of sleep will be reflected in the next revision of the Society of Critical Care Medicine’s Pain, Agitation, and Delirium (PAD) Guidelines. The 2017 revision will now be called PAD-ES, with the E standing for exercise and the S for sleep. Increasing the amount of deep sleep is one of the two most important treatments for delirium, as sleep deprivation affects cognitive functioning and is associated with increased frequency of delirium. Sleep deficit also is associated with adverse physiologic changes. For example, sleep deprivation has been associated with increases in norepinephrine and cortisol levels as well as a decrease in growth hormone levels and increased insulin resistance.1 These changes are associated with worse outcomes in the ICU. Reduction in quality sleep also can result in decreases in inspiratory muscle endurance.2 Understanding the mechanisms of sleep deprivation in the ICU may help clinicians modify some of these factors to promote better quality sleep.
Patient-specific risk factors for sleep deprivation in critically ill patients include type and severity of underlying disease, pain, stress, anxiety, and the underlying pathophysiology of their acute illness.3 Despite the need to learn more about this topic, it is very difficult to conduct quality sleep research in the ICU. While polysomnography is the gold standard, traditional electroencephalogram (EEG) findings of sleep are not routinely present in ICU patients. EEGs also require skilled personnel to apply and interpret the data. As a result, there are very few high-quality sleep studies in this patient population. Patients in the ICU have marked deficits in slow wave sleep (stages 3 and 4), while rapid eye movement (REM) sleep is often completely abolished. The majority of patients’ sleep is stage 2, and their sleep cycles are frequently very fragmented.4
Even without rigorous sleep studies, we can associate other factors with sleep deprivation. For example, the ICU environment itself promotes sleep disruption (see Table 1). Peak noise levels in the ICU have been measured as high as 85 decibels, well above the Environmental Protection Agency’s recommended safe levels and higher levels known to result in arousals from sleep. Noise emits from multiple sources, including alarms, staff conversations, televisions, ventilators, pagers, phones, and patients’ families. In the few studies that have attempted to link environmental noise to arousal levels, noise was found to be the etiology of sleep disturbance in about a quarter of cases. This suggests that most arousals are not caused by noise but other factors. One such cause is abnormal light exposure. High levels of light (as high as 1000 lux) can result in a disruption of the normal nocturnal secretion of melatonin and the circadian pacemaker. Lack of exposure to natural light during the day also disrupts this normal circadian pattern. Another factor is patient care activities, such as nursing procedures, taking vital signs, lab draws, X-rays, and invasive procedures, which all result in sleep interruption. In one study, the average patient in a medical ICU experienced a mean of 19 patient care interactions per night shift, any one of which could cause arousal from sleep.5 In addition, patients on mechanical ventilators have very poor quality sleep. These patients experience up to 80 arousals per hour from sleep, or one interruption every 45 seconds.6 Medications affect sleep quality and architecture as well. Benzodiazepines prolong stage 2 sleep and decrease slow-wave and REM sleep. Propofol, narcotics, beta-blockers, and even quinolone antibiotics have all been reported to disrupt sleep. While these medications often may be necessary, dosage, frequency, and even choice of medications are modifiable elements of care to consider as they relate to sleep and the development of delirium.
While sleep is important, it is only one element to consider in the overall care of the critically ill patient. The underlying illness drives the potential need for frequent monitoring, interventions, and medications. Clinicians know some information regarding attempts to modify these factors. Alternate modes of ventilation have been tried to improve sleep quality with little to no success. In one study, use of dexmedetomidine in mechanically ventilated patients did not improve sleep quality but completely abolished deep REM sleep.7 Benzodiazepines are known to abolish restorative REM and deep non-REM sleep. One low-risk treatment that may help is melatonin. One small trial of melatonin 10 mg daily resulted in improvement of nocturnal sleep efficiency in critically ill patients.8
Attempts also have been made to modify the environment of care to improve sleep quality (see Table 2). Use of earplugs is one low-tech attempt to reduce noise that has been associated with a significant reduction in risk of delirium, although it’s unclear to what extent this may also affect sleep architecture.9 In addition, concerted efforts to decrease environmental noise include closing doors, turning off televisions, lowering the volume on medical equipment, and reducing staff-patient interactions. The concept of a period of “quiet time” by bundling these interventions has been studied. For example, a two-hour quiet time with reduced light and sound exposure and minimized patient interruptions has been associated with less need for sedation and a trend toward less delirium.10 This quiet time, however, was very difficult to implement due to the inherent instability of patients and the need for ongoing important patient care interactions.
Quality sleep is a very important component in the treatment plan for critically ill patients. Clinicians must balance the need for optimal sedation and quality sleep against the need for frequent care interventions and monitoring while minimizing delirium. In the past, physicians and nurses have simply assumed patients would not sleep because of a combination of factors, including severity of illness, need for frequent interruptions for patient care, and the noisy environment. Some low-tech, low-cost, low-risk methods are available to improve patients’ ability to sleep in the ICU. However, the best thing to do is to transition patients out of the ICU as quickly as possible. For those that require longer stays, perhaps start by introducing a couple of periods of extended quiet time into each patient’s day. Bundling vital signs, medication administration, and nursing care around these periods may go a long way toward increasing quality sleep. These likely will incrementally result in improved quality of care, and may also improve physiologic and long-term outcomes.
- Schmid SM, Hallschmid M, Jauch-Chara K, et al. Sleep loss alters basal metabolic hormone secretion and modulates the dynamic counterregulatory response to hypoglycemia. J Clin Endocrinol Metab 2007;92:3044-3051.
- Chen HI, Tang YR. Sleep loss impairs respiratory muscle endurance. Am Rev Respir Dis 1989;140:907-909.
- Bihari S, Doug McEvoy R, Matheson E, et al. Factors affecting sleep quality of patients in intensive care unit. J Clin Sleep Med 2012;8:301-307.
- Drouot X, Quentin S. Sleep neurobiology and critical care illness. Sleep Med Clin 2016;11:105-113.
- Giusti GD, Tuteri D, Giontella M. Nursing interventions with intensive care unit patients affected by sleep deprivation: An observational study. Dimens Crit Care Nurs 2016;35:154-159.
- Cooper AB, Thornley KS, Young GB, et al. Sleep in critically ill patients requiring mechanical ventilation. Chest 2000;117:809-818.
- Oto J, Yamamoto K, Koike S, et al. Sleep quality of mechanically ventilated patients sedated with dexmedetomidine. Intensive Care Med 2012;38:1982-1989.
- Bourne RS, Mills GH, Minelli C. Melatonin therapy to improve nocturnal sleep in critically ill patients: Encouraging results from a small randomized controlled trial. Crit Care 2008;12: R52.
- Litton E, Carnegie V, Elliott R, et al. The efficacy of earplugs as a sleep hygiene strategy for reducing delirium in the ICU: A systematic review and meta-analysis. Crit Care Med 2016;44:992-999.
- McAndrew NS, Leske J, Guttormson J, et al. Quiet time for mechanically ventilated patients in the medical intensive care unit. Intensive Crit Care Nurs 2016 Feb 22 [Epub ahead of print].