The number of hours people sleep is at least as important as our blood pressure, smoking status, diet, and exercise habits.
The evidence shows that people whose lives are synchronized with their body clock are less fatigued, have better moods, maintain healthier weights, gain more benefit from their medications, think more clearly, and have improved long-term health outcomes.
Sleep itself has cycles, in which the brain and body move through phases, marked by varying brain activity. In the deepest phases of sleep, the brain waves are slowest. The lighter phases have more rapid bursts of activity.
Our most intense dreams usually happen during Rapid Eye Movement (REM) sleep, when brain activity, breathing, heart rate, and blood pressure all increase, the eyes move rapidly, and muscles are limp. Scientists believe dreams in REM and non-REM sleep have different content – the more vivid or bizarre dreams usually happen during REM stages.