Why The Four Stages of Sleep Are So Important

by Martin Reed Patient Advocate

Prior to the 1950’s, sleep was thought of as a time when nothing occurred. But research has shown the opposite to be true. During sleep, our brain is busy processing and storing memories and cleaning itself of waste. That’s why each of these four stages of sleep serves an important purpose for your mental and physical health.

First stage

The first stage of sleep is the lightest, and for a normal sleeper makes up roughly 10 percent of sleeping time. During this stage, daydream-type thoughts take over as the body begins to prepare for deeper sleep. If you have ever felt your body jerk awake or felt that you were falling, it was during this stage of sleep - where your brain is still tuned to outside stimuli.

Second stage

The second stage of sleep is when most of your sleeping time occurs. Typically, you are unaware of outside stimuli, your body temperature drops and your heart rate slows. While your body rests, your brain remains active, producing rapid, rhythmic brain waves for short periods of time,. It also prepares to transition to the next phase of sleep.

Third stage

The third stage of sleep is the most restorative stage. It is when your brain begins moving from a light sleep into a deep slumber. Brain waves are slow. Outside stimuli would have to be pretty intense to wake you.

Fourth stage

This is when the brain becomes most active, while the body’s voluntary muscles go into an almost-paralysis. This is also known as the dreaming stage. It is believed that this is what gives you a mental boost when you wake up and throughout the day. This is the stage in which the brain consolidates emotions, memories and stress. If this stage of sleep is disrupted, the brain will try to go through it more often the next time you sleep.

Repetition of sleep stages

The four stages of sleep are cycled through more than once a night. After the brain goes through stages one through four, it will cycle down to stage three, then two, and then go back into stage three, followed by four again. This repeats numerous times in normal sleep.

Insomnia's effect on sleep stages

Having insomnia, interrupted sleep, or early awakening is not good. It means the normal sleep cycle is not able to do its work in the brain and body. If insomnia is not dealt with, it can have numerous complications.

Martin Reed
Meet Our Writer
Martin Reed

Martin is the creator of Insomnia Coach, an eight-week course that combines online sleep education with individual sleep coaching. His course helps clients improve their sleep so they can enjoy a better life with more energy and start each day feeling happy, healthy, rested, and refreshed. Martin also runs a free sleep training course that has helped over 5,000 insomniacs. He holds a master’s degree in health and wellness education and studied clinical sleep health at the University of Delaware.