The brain coordinates timing
A central clock in the brain helps synchronize sleep-wake patterns with day and night.
Cells also keep time
Many tissues contain molecular clocks that influence gene activity and metabolism.
Light is a major timing cue
Retinal signals help align the internal clock with the external light-dark cycle.
Dreams are a separate research question
Dreaming occurs during several sleep stages, but scientists continue studying its functions rather than having one settled explanation.
This page explains scientific concepts for general learning. It does not replace laboratory safety procedures, professional engineering guidance, or individualized medical advice.