Interim NIOSH Training for Emergency Responders: Reducing Risks Associated with Long Work Hours

The Color of the Light Affects the Circadian Rhythms, Cont.

Figure 4

Graph depicting why humans tend to feel sleepy and sometimes take a nap in the middle of the afternoon. At this time, circadian rhythms that promote wakefulness dip, and sleep drive builds so that pressure to sleep dominates.

If you feel drowsy in the middle of the afternoon, a 15- to 30- minute nap will help restore your alertness.

Graph depicting why humans tend to feel sleepy

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Page last reviewed: April 1, 2020