In sleep, all the voluntary muscles remain inactive and involuntary muscles functions are reduced. In other words, it is like switching off a machine or placing it in idle mode to allow the machines to cool off and prevent damage. It is mostly done at night where hormone levels are at the lowest.

A person’s sleep can be affected by a lot of factors one of these factors include the circadian rhythm. The sleep-wake homeostasis or the circadian clock controls the sleep timing. It may have the greatest significance and greatest effect on the sleep of an individual. Sleep timing means the time you sleep and the time you wake up. The circadian clock is also an inner time keeper, temperature controller, and an enzyme regulator. It is the rhythm that determines the ideal time for a person’s restorative sleep and rest. It works together with a neurotransmitter called Adenosine.