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Stages of the Sleep Cycle: Here's What Happens to Your Body When You Sleep

When you think of sleep, the first things that probably come to mind are rest, relaxation and stress relief. But while it may seem like that’s all your body is doing when you nod off, there’s actually a lot more going on than meets the eye. Your sleep cycle has many stages, and they all have different functions. Understanding what happens in each stage can help you get a better night’s rest and improve your quality of life in general. Keep reading to learn about the five stages of the sleep cycle and what happens in each one.

bed in moody light stages of sleep cycle

Stage 1 Sleep

When you first start falling asleep, you’ll first enter stage 1 sleep. In this first stage, your heart rate and blood pressure drop, along with your body temperature. Your muscles relax, and your breathing and brain activity slow down. You may experience hypnic jerks, which are sudden, quick muscle spasms that sometimes make you jump. Stage 1 sleep usually lasts between 5 and 10 minutes and can be described as a phase of perceived drowsiness.

Stage 2 Sleep

The second stage of sleep is called light sleep. You might experience hypnagogia in this stage, which is the sensation of hearing or seeing things that aren’t actually there, like sounds, voices, sights, smells and tastes. You might also experience leg cramps, restless legs or a feeling of falling. Vibrating alarms, like a cell phone or smartwatch, should not wake you from this stage of sleep. It takes a loud noise or vibration to jar you out of light sleep, like a fire alarm or a loud doorbell. Your brain is still active in this stage, and you may dream lightly. This phase usually lasts about 20 minutes.

Stage 3 and 4 Sleep

Your heart rate, blood pressure and breathing rate go down even further in stages 3 and 4. Stage 3 is the moderate sleep phase: your body temperature drops, and your muscles become completely relaxed and motionless. If there is no outside disturbance, the body will fall into stage 4: the deep sleep stage. In stage 4, brain activity slows down to very low levels. Tossing and turning, spasms or jerking, and feeling hot and sweaty are signs that you’re not getting enough deep sleep. Deep sleep or stage 4 sleep is very important because it's in this stage that the body releases growth hormones to help muscle repair. It’s also when the liver and kidneys do their cleaning. This phase usually lasts about 30 minutes; then, the body will try to slide into REM Sleep.

Rapid Eye Movement (REM) Sleep

The fifth stage of sleep is when you transition into Rapid Eye Movement or REM sleep. In this stage, your brain becomes active again, and your muscles start to twitch. This is when you’re likely to have the most vivid dreams, which is why this stage is sometimes called dream sleep. A few hours of uninterrupted REM sleep is what your body needs every night. If you don’t get enough REM sleep, you feel tired and you don’t function properly.

The Importance of Napping

A nap may not substitute a good night's sleep, but napping is important for your health and well-being, especially as you get older. Napping can help you: relieve stress, improve your mood, increase productivity, boost immunity, and even improve your eyesight. Studies have shown that napping can also lower blood pressure, increase heart rate variability and help to regulate blood glucose levels.

How to Improve the Quality of Your Sleep

Many factors can affect the quality of your sleep, like your physical, psychological and environmental surroundings. There are, however, a few things you can do to improve the quality of your sleep. Here are a few tips to help you get a better night’s rest.

  • Eat well and get regular exercise: eat a balanced diet and stay active. Being healthy not only helps you get a better night’s sleep, but it also helps you live a healthier life in general.

  • Create a sleep ritual: having a sleep ritual helps your body and mind prepare for sleep. You can do yoga, read, draw, write in a journal or try breathing exercises to help you relax.

  • Avoid stimulants: if you want to get a good night’s sleep, you need to avoid things that keep you awake, like caffeine and nicotine, which are stimulants. Exercising right before bed can also be considered a stimulant, as it increases heart rate and can make it harder for your body to calm down and drift off into sleep. A moderate exercise 60 to 90 minutes before going to bed is ok, but it's probably best to lay off a high-intensity workout if it's already late.

  • Reduce blue light exposure at night: our bodies are programmed to sleep when it’s dark, so you should avoid bright blue light in the evenings, like that emitted from your phone or computer screen. Instead, prefer a book or a Kindle reading, or maybe a little meditation.


When you understand what happens in each stage of the sleep cycle, it’s easier to see how important sleep is for your health and well-being. Getting enough sleep every night is one of the best things you can do for your health and happiness. You can start to improve the quality of your sleep by making sure you follow these simple steps: eating healthily, creating a sleep ritual, avoiding stimulants, and reducing blue light exposure at night.


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