NIOSH Training for Nurses on Shift Work and Long Work Hours

Sleep Pressure: Homeostatic Sleep Drive

Pressure for sleep (homeostatic sleep drive) builds up in our body as our time awake increases (“sleep pressure” in Figure 2.3). The pressure gets stronger the longer we stay awake and decreases during sleep, reaching a low after a full night of good-quality sleep. The homeostatic process begins to build again after we awaken. The dashed line in Figure 2.3 represents potential increases in pressure to sleep, which will continue to build if sleep does not occur.

Our body produces a higher drive for sleep under some circumstances. When the immune system is fighting an infection, it produces more immune mediators, which cause more sleepiness. Also, cognitively stimulating or demanding experiences (such as sightseeing) and physically demanding experiences could increase sleep pressure further. As a result, our sleep may be longer and deeper after those experiences.

Figure 2.3. Homeostatic sleep drive is the pressure to sleep ("sleep pressure" on graph).