NIOSH Training for Nurses on Shift Work and Long Work Hours

Sleep Pressure: Homeostatic Sleep Drive (Continued)

Not getting adequate sleep causes a “sleep debt” to build over time; sleep is needed to “pay down” this debt. For example, a person needing 8 hours of sleep but getting only 6 hours would accumulate a sleep debt of 2 hours that day. A person with an 8-hour sleep need who gets 6 hours of sleep each day for 5 days accumulates a sleep debt of 10 hours.

To keep sleep debt down, get the length of sleep you need in order to feel rested when you wake up. Allow extra time to sleep if you were not able to get enough sleep the previous night. A person does not necessarily need to pay back hour for hour the lost sleep, since the body sometimes sleeps more soundly to pay down the debt. Ongoing fatigue, sleepiness, and other negative effects during wake time could reflect a build-up of sleep debt.

It is risky to build up a sleep debt and try to pay it off later. Although your level of sleepiness may return to normal after a day or two of recovery sleep, your neurocognitive performance can still be lower than baseline.^22-24 Thus, getting adequate sleep on a regular basis, rather than episodically, is important. This is especially important if you work 12-hour shifts, do not sleep much between them, and then try to catch up on sleep after the block of shifts ends.