Sleep Deprivation in the ICU

If you’ve ever stayed overnight in a hospital, you may have had trouble sleeping amidst the beeps, bright lights, and nighttime interruptions. Melissa Knauert, MD, PhD, associate professor in Yale’s Section of Pulmonary, Critical Care and Sleep Medicine, understands the challenge. For the past 12 years, she’s been working to make the ICU less disruptive to sleep.

Knauert first became interested in studying sleep deprivation in the ICU when she was a pulmonary and critical care fellow at Yale School of Medicine, working alongside mentors Margaret Pisani, MD, MPH, and Klar Yaggi, MD, MPH. At the time, Knauert was focused on nighttime disturbances, studying things like how many times people went in and out of patients’ rooms, the frequency with which patients received nonurgent care, and the levels of sound and light in patient rooms.

Then, during her sleep fellowship, Knauert was introduced to an expanded view of the circadian system—the body’s internal clock. The new science led Knauert to pivot her work to focus on leveraging circadian principles in the ICU to promote sleep. She began studying the ICU environment not only at night but also during the day.

“It turns out that it really matters that you are active during the day with high levels of light, eating, exercising, having social interactions, and being cognitively active,” she said. “Conversely, you should sleep and be in the dark at night.”

Different organ systems are designed to function at certain times, and it’s important that we ask them to function at those times, she added.

In a Q&A, Knauert discusses the impact of sleep on recovery from illness, the importance of circadian alignment, and tips for protecting sleep during hospital stays.

Sleep is fundamental to physical and mental health. Sleep loss negatively impacts many different systems in the body.

For example, eating in the setting of sleep deprivation or at noncircadian times, such as nighttime, has a deleterious effect on metabolism. The same food that you might’ve eaten at breakfast has worse effects on your body if you eat it in the late evening. By nighttime, we’re all slightly diabetic. Even worse is the combination of being sleep deprived and eating at the wrong time. The worst thing you can do is eat during sleep, which happens when patients are tube fed in the ICU.

Sleep deprivation and circadian misalignment also contribute to immune dysfunction. A recent study looked at people’s immune responses to the COVID vaccine according to the time of day they received it. The researchers found that the vaccine was more effective when given during the day than in the evening.

It also turns out that sleep deprivation makes people more susceptible to cardiac arrhythmias. For example, at the start of Daylight Savings Time, when we spring forward and everyone has lost about an hour of sleep, we have increased rates of strokes, heart attacks, and car accidents due to that subtle sleep deprivation and circadian misalignment caused by the time shift.

Finally, when you’re sleep-deprived or circadian misaligned, you don't have as much muscle strength. And in the ICU, where many patients are on ventilators, the physical ability to breathe is often a muscular process as is doing rehab or participating in physical therapy.

There are four stages of sleep: N1, N2, N3 and REM. Stages N3 and REM are where we get our restorative, healing sleep and clean out our brain systems. But in the ICU, people almost exclusively get light stages of sleep—N1 and N2. If you do sleep in the ICU, the data shows that you wake up—you have what’s called arousal—30 to 40 times an hour compared with the normal range of five to 10. ICU patients can’t get the type of sleep needed for recovery.

Sleep deprivation in the ICU can lead to delirium, a complication of critical illness that portends longer stays in the hospital, higher death rates, and less of a chance of getting back to the level of function you were at before you were admitted. If you have delirium in the ICU, you're less likely to be able to go back to paying your bills, balancing your checkbook, or doing other activities within a year. You’re more likely to go into a nursing home. The data all points in the direction of significant harm.

This issue is a challenge in most busy, modern hospitals. Part of the onus is on hospitals to be willing to not do certain things at night. But it’s a double-edged sword because patients want to get out of the hospital. We’re in too much of a hurry to protect sleep.

When doing research, I found that not only is it bright in the ICU at night, but it’s also super dim during the day. And I had this revelation that what really matters is what we’re doing during the day. The most powerful circadian cue is light. However, sleep, food, temperature, exercise and many other things can influence circadian timing.

When staying overnight in the hospital or ICU, you can ask for lights to be turned off at night and express individual preferences, such as what time you go to sleep and wake up. I recommend patients use earplugs and eye masks. Also, try to be active, with the lights on, during the day. You can take a consolidated afternoon nap—an intentional time of rest—not too close to bedtime.

The other piece of advice is for family and friends, who can help communicate a patient’s preferences. Often, I am struck by how sleep deprived families become, especially in the ICU. I often say to my families, “This is a marathon, not a sprint. I know you want to be with so-and-so, but you can’t get sick, right? You can't fall apart. To the extent that you feel comfortable, go home, get some rest, and take a shower.”

The Section of Pulmonary, Critical Care and Sleep Medicine is one of the eleven sections within Yale School of Medicine’s Department of Internal Medicine. To learn more about Yale-PCCSM, visit PCCSM's website, or follow them on Facebook and Twitter.