By Eric Walter, MD, MSc
Pulmonary and Critical Care Medicine, Northwest Permanente and Kaiser Sunnyside Medical Center, Portland
Dr. Walter reports no financial relationships relevant to this field of study.
SYNOPSIS: Melatonin supplementation and the use of eye masks and earplugs improved sleep quality among healthy volunteers sleeping in a simulated ICU environment.
SOURCE: Huang HW, et al. Effect of oral melatonin and wearing earplugs and eye masks on nocturnal sleep in healthy subjects in a simulated intensive care unit environment: Which might be a more promising strategy for ICU sleep deprivation? Critical Care 2015;19:124.
Sleep deprivation is common in the ICU and may make patients agitated, delirious, or just plain tired. But beyond these effects, data suggest that sleep deprivation possibly affects the immune system, respiratory mechanics, and hormonal balances.1 The causes of sleep deprivation in the ICU are multifaceted. Excess light and noise, night time evaluations, and procedures cause interrupted sleep. Darkness stimulates normal melatonin secretion and helps maintain routine circadian rhythm, while light interferes with these processes. Critically ill patients lose the ability to regulate melatonin secretion in response to light and dark, with levels often measured very low in them. Some ICU clinicians have suggested the use of ear plugs and eye masks to improve sleep quality, along with melatonin supplementation. However, it is unknown if either of these practices actually improves sleep quality in an ICU environment. This study examined the effect of these measures on sleep quality.
Measuring sleep quality in the ICU is challenging. Polysomnography (PSG) in ICU patients is difficult to interpret. Frequent interruptions, hormonal imbalances, medications, neurologic injury, and other factors affect electroencephalographic patterns. To avoid these concerns, Huang and colleagues studied normal subjects in a simulated ICU environment. The study was comprehensive and well thought out. Forty volunteers underwent PSG on eight consecutive nights. This allowed subjects to become used to the equipment on night 1. Data on sleep quality were then collected under both normal sleeping conditions and in a simulated ICU environment on nights 2 and 3. The simulated ICU included previously recorded ICU sounds and lights specifically set to premeasured ICU light levels. The subjects were then randomized to one of four groups: no treatment, placebo, the use of ear plugs and eye masks, or 1 mg of melatonin supplementation. Sleep quality was then measured for three consecutive nights.
As expected, subjects had worse sleep when exposed to the simulated ICU environment. When exposed to ICU sounds and light levels, subjects had more awakenings (14.4 vs 9.9; P = 0.011), longer sleep latency (66.2 vs 23.4 minutes, P < 0.001), less REM sleep (15.8 vs 21.9%; P = 0.006), and slept about 1 hour less (359.2 vs 424.3 minutes, P < 0.001). Subjects also had lower melatonin levels on nights in which they were exposed to the ICU environment compared to their baseline nights. During the intervention portion of the study, several measures of sleep quality (both objective and subjective) improved in both of the groups randomized to the use of ear plugs, eye masks, and melatonin. No improvements were seen in the group randomized to placebo. When compared to ear plugs and eye masks, melatonin improved subjective sleep quality more than ear plugs and eye masks. Melatonin use was also associated with fewer awakenings than ear plugs and eye masks, but all other objective measures of sleep quality were not significantly different.
At first glance, this article may not seem relevant to the practicing ICU clinician. Huang and colleagues evaluated sleep aids in normal, healthy, volunteer subjects in a simulated ICU environment. It is true these findings may not apply to ICU patients who may be hypotensive, intubated, sedated, or otherwise. However, this study serves as proof of concept. Huang and colleagues show that sleep quality in an ICU environment can improve with the use of ear plugs and eye masks or melatonin supplementation. Hopefully, these background data will be useful to inform future studies in ICU patients. How should the practicing clinician interpret these findings? With caution. It would be overreaching to believe these data prove the efficacy (and safety) of either of these interventions. The data support the concept, but these questions must be further evaluated in future studies.
Obtaining quality sleep may be one of the last priorities in the ICU. Sleep sits below the history and physical exam, nurses admit paperwork, central venous catheters, routine neuro checks, and so on. In fact, sleep sits so low on the ICU totem pole that we routinely schedule blood draws and bathing between 3 a.m. and 5 a.m. Fortunately, the potential negative consequences of poor sleep are beginning to be discussed. Attempts to improve sleep are being implemented, albeit, without much data. It is somewhat naïve to assume we can plug our patient’s ears and cover their eyes and they will get a good night’s sleep. By the same token, the concept that simply replacing low melatonin levels in sleep-deprived patients will improve sleep sounds good, but belies the fact that we could be potentially causing harm. Although preliminary, studies such as this provide important data to guide research into how we can best improve our patient’s sleep.
- Pisani MA, et al. Sleep in the intensive care unit. Am J Respir Crit Care Med 2015;191:731-738.