Everybody has to sleep, whether we want to or not. It is important to focus on how much sleep you are getting, learn more in our Healthy Sleep Habits blog. However, duration is not the only part of the sleep equation. When it comes to a good night’s rest, quality is just as important as quantity. A full night of sleep consists of four sleep stages that last for around 90 minutes each. It is normal for sleep cycles to change because they vary from person to person based on a number of factors like age, diet, and activity level.
Stage 1 : NREM, N1
This first stage is known as the “dozing off” stage. The body has not fully relaxed yet and will have brief twitches for the first 1-5 minutes. When people are dozing off, it is easy to wake up.
Stage 2: NREM, N2
The second stage of sleep helps the body begin to deep sleep by dropping temperature, relaxing muscles, and slowing both breathing and heart rate. Brain activity also begins to slow during this stage but there are short bursts of activity. As each N2 stage becomes longer during the night, a person will typically spend half of their sleep time in this stage.
Stage 3: NREM (slow wave), N3
Stage 3 is known as deep sleep and is harder to wake someone up. Muscle tone, pulse, and breathing rate will decrease and delta waves can be identified in the brain. This third stage allows the body to recover and grow, as well as improve the immune system. Deep sleep is important because it contributes to insightful thinking, creativity, and memory.
Stage 4: REM, Rapid Eye Movement
This final stage is essential to cognitive functions like memory, learning, and creativity because brain activity picks up. The body experiences temporary paralysis of the muscles, except for the eyes and breathing muscles. People will experience the most vivid dreams during this stage but most people don’t enter REM until they’ve been asleep for about 90 minutes.
Sleep is essential because it allows the brain and body to recuperate and develop. Not enough deep sleep and REM can have consequences on thinking, emotions, and physical health. You can improve your chances of a healthy progression to each cycle with adequate sleep hygiene and positive sleep-related habits. If you have consistent fatigue or suspect a sleep disorder, talk to your doctor or a sleep specialist.