Sleep Centers of Middle Tennessee

When Do We Sleep?

Posted on 14 Apr 2011 - 4:13 PM

Humans respond to circadian rhythms, or a “biological clock.” Certain structures in the brain (the superchiasmatic nucleus) are responsible for coordinating the biological clock. These brain structures are sensitive to light and dark. Some have argued that this results in daytime sleep being less restful than night sleep. Daylight normally triggers periods of wakefulness. As humans, we experience “sleepy peaks” which occur every 12 hours – at night and in the afternoon.