How Many Hours Are in Each Sleep Cycle?

When you fall asleep at night your brain keeps on being active. An electromyogram (EMG) machine records your sleep cycles with a pattern of waves. These waves are used to determine the stage of sleep that you are in and the length of that stage. Some of these stages are repeated during your sleep cycle.

Stage 1

If you are awakened during stage 1 you may feel that you have not slept at all. This stage of sleep lasts 5 to 10 minutes.

Stage 2

During stage 2 there are periods that muscles tighten and periods that muscles relax. Your heart rate will slow down and your body temperature decreases. Your body is preparing to enter a deeper sleep. This stage can last 5 to 15 minutes.

Stages 3 and 4

Stages 3 and 4 are our deep sleep stages. Both stages show slow waves to indicate a deep sleep. Stage 4 is a deeper sleep than stage 3. These stages can last 60 minutes together.

Non-REM Sleep

This period lasts from 90 to 120 minutes and it includes stages 1 through 4.

Stage 5 REM

Your eyes will show rapid movements and your pulse and breathing will increase. Dreaming occurs during this stage and your fingers, legs and face may twitch. REM sleep starts 90 minutes after you fall asleep.

REM

The first REM period will last 10 minutes and then each REM stage after that will be slightly longer. The last REM period can last 1 hour.