The stages of sleep: what happens to your body while you rest?

The stages of sleep: what happens to your body while you rest?
November 22, 2019 Philip Stein

For a long time, people thought that when we slept, our body and mind went into and stand-by mode, which allowed us to rest and recover energies for the day to come. Nothing farther from the truth. Our brain is very active during the night, and multiple processes take place. Memories and skills learned during the day are moved to more permanent regions of the brain (it’s a process called consolidation); the levels of inflammation in the body are regulated, which can reduce the risk for heart-related conditions, as well as cancer and diabetes; it also regulates the production of chemicals in your body, and repairs damage caused by stress, ultraviolet rays, and other harmful exposure.

To enjoy truly restful sleep, your body should go through the different stages of sleep, as each of them has a particular function in your wellbeing.


There are four of them: Non-REM (NREM) sleep (Stages 1,2, & 3) and REM sleep.

STAGE 1: It’s the first transition to a sleep state, and due to its lightness, you are very prone to wake up, and even fail to realize you were asleep. Muscle tone throughout the body relaxes, and brain wave activity begins to slow down. During this stage, it’s very common to experience that sensation of falling.

STAGE 2: Here, the body prepares to get truly quality sleep, and you are not as likely to wake up as in STAGE 1. Brain waves keep slowing down, and eye movement ceases. This stage represents about 50% of our overall sleep cycle. Body temperature begins to drop, and the heart rate begins to slow.

STAGE 3: Known as deep NREM sleep, it’s the most restorative stage. The brain starts producing slower delta waves, and eye movement or muscle activity stops entirely. As you go into a deep rest, it’s a stage where waking up suddenly becomes less likely. Your body is not as responsive to outside stimuli, and your heartbeat and breathing slow to their lowest levels.

REM SLEEP (Rapid Eye Movement): This is the dreaming stage. Eyes move from side to side rapidly, and brain waves are more active than in previous stages. It can last up to an hour approximately and usually starts 90 minutes after you fall asleep. An average adult has five to six REM cycles each night, and if you wake up during one of them, you might feel groggy or overly sleepy.

Most nights, you should go through the different stages sequentially with the most prolonged REM period right before awakening for the day.


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