You probably learned about them in school, but you may have forgotten more than you remember about sleep cycles. But understanding our sleep cycles may provide you some insight on why you might be feeling tired during the day or how to maximize your sleep and waking hours. In this post we want to give you a little refresher on the human sleep cycle so you can understand your body a little better and have an appreciation for what happens after your head hits the pillow.
The Human Sleep Cycle Unpacked
The typical sleep cycle lasts for 90 minutes. In these 90 minutes, the human body goes through five stages of sleep. If you are a visual learner, check out this helpful graphic on the sleep cycle from Psychology Today. The five stages are:- Stage 1—Light Sleep: Light sleep lasts for about 5% of the sleep cycle and is when your muscles begin to relax, perhaps with some muscle twitching.
- Stage 2: This stage makes up the majority of your sleep cycle, from 45-55% of that 90 minute cycle. During this time your breathing and your heart rate slow down and your body temperature has a slight decrease as well.
- Stage 3—Deep Sleep: This lasts for just a short amount of time, only 4-6% of the cycle and is when your body begins to generate slow delta waves.
- Stage 4—Very Deep Sleep: Spanning 12-15% of your sleep cycle, your body is producing delta waves. There is very little movement in the body and breathing is rhythmic.
- Stage 5—Rapid Eye Movement: This is the section of your cycle when brainwaves speed up and people have dreams. The cycle lasts for 20-25% of the cycle. The breath is quick and shallow.