Trying to Get Some Shut-Eye in the Worst Place to Sleep

BY GAURAV SINGH

It is not easy sleeping in the intensive care unit (ICU). Many patients experience insufficient sleep quantity and fragmented sleep, and they complain of poor sleep quality. Although environmental controls, such as dimming lights and avoiding noise and unnecessary interruptions during nighttime hours are first-line recommendations to support sleep in the hospital setting, they can be difficult to implement in the ICU. Similarly, ear plugs and eye masks are underutilized despite being safe, effective, and inexpensive interventions that can improve sleep quality in the ICU. Instead, ICU doctors often turn to medication-based sleep aids, typically in the form of a sleeping pill.

While we do not fully understand why we need to sleep, we know it is vital for survival. In fact, it is believed that nearly every animal sleeps, so it is highly conserved in evolution. We know that sleep deprivation, after a certain point, is fatal to animals. For humans, one of the more acute risks associated with sleep deprivation in the hospital is delirium. This is a reversible change in mental status often characterized by severe confusion and disorientation, and it is associated with a high death rate in hospitalized patients.

The pain and anxiety associated with many critical illnesses commonly contribute to sleep disturbances among ICU patients. Additionally, they often experience sleep interruptions for vital signs, blood draws, and administration of medications and other treatments. This is compounded by an environment that is commonly noisy and brightly lit. It is not surprising that patients experience poor sleep quality in the ICU and have difficulty achieving deeper stages of sleep. Moreover, they often have their internal clocks altered, resulting in frequent sleep during the daytime, which contributes to the risk of delirium.

There is no medication specifically approved for use in the ICU to improve sleep quantity or quality. ICU physicians sometimes use medications such as melatonin, an unregulated supplement that mimics the natural sleep hormone our bodies produce at night. Other medications that are commonly used are approved to treat another health problem but may have the additional effect of promoting sleepiness, such as antihistamines, antidepressants, and antipsychotics. Professional societies do not recommend use of these medications for insomnia, largely based on a lack of supporting data demonstrating effectiveness and because of the risk of harm. Approved sleep aids, such as zolpidem, can pose risks, such as falls. Moreover, their effects on reducing time to falling asleep and extending total sleep time is on the order of minutes in the outpatient setting. If these medications have a nominal effect in an ideal sleep environment, they cannot be expected to have meaningful benefit in the ICU setting. Additionally, evidence for use of newer sleeping pills in the ICU is limited.

Dexmedetomidine is a medication administered as an infusion that was approved in 1999 for sedation in the ICU for patients on mechanical ventilators. It acts in the brain to decrease the flight-or-flight response. Now available in generic formulation, it is widely used in ICUs. It does not suppress the breathing drive, so it is safe to use without a ventilator, but it can decrease heart rate and blood pressure, although rarely to a point that is dangerous. These features make it a generally safer alternative to propofol, which is often used for general anesthesia in addition to sedation.

One of the unique features of dexmedetomidine is that is induces a state mimicking natural sleep. Although studying sleep in the ICU is quite challenging, doing so by monitoring brain waves has demonstrated that dexmedetomidine used as a continuous infusion throughout the night increases total sleep time and sleep efficiency. It also reduces the proportion of time spent in the lightest stage of sleep. Therefore, dexmedetomidine can improve both the quantity and quality of sleep in ICU patients.

Sleep and wakefulness can be likened to turning a switch off and on in the brain. While sleep is certainly more complex than this, dexmedetomidine can analogously be turned on at night and off in the morning in the ICU to assist with nocturnal sleep and to synchronize the internal clock. By helping our critically ill patients achieve better sleep, we may be improving their hospital experience and outcomes.