G47: Sleep disorders

G47.2: Disorders of the sleep-wake schedule

There are different reasons why we sleep. The reasons have not been fully understood. So far we know, for example, that sleep helps the body to recover. Sleep also develops the memory, and it brings feelings into equilibrium. Sleep has a particular sequence. There are deep sleep phases and lighter sleep phases. These phases alternate during sleep. The sleep-wake cycle is controlled by different influences such as messenger substances in the body. These messenger substances can be influenced by activity and light.

Your sleep-wake cycle has changed or is no longer consistent. You sleep when other people are awake. Or you are awake when other people are sleeping.