Decoding the Sleep Cycle: An Overview of the Stages of Sleep 

Your sleep cycle consists of four stages of sleep, all of which are vital for healthy sleep. Learn more about these stages and what happens during each of them.


Sleep is one of the most important activities that you do. You spend about one-third of your life sleeping. While you are sleeping, your body cycles through four different stages of sleep — N1, N2, N3, and REM. These stages are all different and your eye movements, muscle activity, and brain waves vary during each stage.  

What Are the Stages of Sleep?  

The four stages include two different types of sleep, non-rapid eye movement (NREM) and rapid eye movement (REM). Non-rapid eye movement sleep is divided into three types: N1, N2, and N3. Keep reading to find out what happens in each stage. 

NREM Stage 1  

This is the stage of sleep that you enter when you first fall asleep. It begins your sleep cycle and lasts between one and five minutes. During this phase, you are in a light sleep. It’s easy to wake up. Your muscles may twitch and your body relaxes. Your breathing, brain waves, and heartbeat all begin to slow down.  
Why It’s Important: This stage of sleep helps prepare you for the deeper stages of sleep.  

NREM Stage 2  

This is a period of deeper NREM sleep. It lasts between 10 and 25 minutes. As the night goes on, the amount of time you spend in this stage becomes longer. During this stage,  
your heartbeat and breathing slow down. Your muscles begin to relax. You may experience a drop in body temperature during this phase. You spend the majority of your sleep time in this stage. It accounts for about 50 percent of total sleep time for most adults.   
Why It’s Important: Your brain collects and organizes memories during this stage of sleep.  

NREM Stage 3  

Also called Delta wave sleep for the brain wave patterns seen during this stage, N3 is the deepest stage of sleep. It lasts 20-40 minutes. During this stage, your heartbeat, muscles, and breathing are all relaxed and slow. It’s difficult to awaken from this stage of sleep, If you do wake up, you are likely to feel disorientated and groggy. Stage N3 is also the most restorative sleep stage. It’s what helps you feel reinvigorated and energetic when you wake up in the morning.  
Why It’s Important: During this stage the body repairs bone and tissue and the immune system is strengthened.  

REM Stage 4  

During the rapid eye movement (REM) stage of sleep is when most of your dreaming occurs. Your eyes move rapidly under your eyelids during this stage of sleep. This stage begins about an hour and a half after you fall asleep. It lasts anywhere from 10 minutes to an hour. The length of REM sleep increases as the night progresses. As you get older, you will spend less time in REM sleep.  
While in REM sleep, your brain wave activity resembles that of when you are awake. Compared to the other stages, your heartbeat increases, blood pressure increases and your breathing becomes more rapid. You may have intense dreams or nightmares during REM sleep since your brain is more active. Fortunately, your body is paralyzed so that you don’t act out your dreams.  
Why It’s Important: Rapid eye movement sleep is important for the production of proteins and learning.  

Things That Affect Your Sleep Cycle

Here are just a few of the things that can impact your sleep cycle.  

Drugs and Prescription Medications

Benzodiazepines, barbituates, and alcohol all lessen the amount of time that you spend in REM sleep. Other drugs that can decrease the amount of REM sleep include antidepressants like Venlafaxine, lithium, and trazodone.  


People who have major depression have a decreased time between falling asleep and beginning their first REM stage. The more severe the depression, the earlier they enter into the first REM. Depression also increases REM sleep.  

Sleep Disorders  

A number of sleep disorders can impact the sleep cycle, including:

  • Narcolepsy - People with narcolepsy don’t go through the typical sleep cycle. This can cause them to feel extremely sleepy during the day. 
  • REM sleep disorder - This occurs during the REM stage of sleep. A person with this disorder doesn’t experience the normal paralysis that occurs during REM sleep. This allows them to act out their dreams.  
  • Sleep apnea - This sleep disorder affects all stages of sleep. It causes a person’s breathing to be interrupted during sleep.  
  • Sleepwalking - Sleepwalking occurs during the deep stage of sleep.


Children spend the most time in deep sleep. That’s why sleepwalking is more common in kids. As we get older, we naturally spend less time in both the N3 and REM stages of sleep.  

How to Improve Your Sleep Cycle  

The National Council on Aging reports that more than a third of Americans don’t get enough sleep. When you don’t get enough sleep in general, it can impact your sleep cycle. If you practice good sleep habits, it can help prevent interruptions in your sleep cycle. Here are some things you can do to improve your sleep quality:  

  • Take time to relax before bed - Make relaxation a part of your nightly wind-down routine. This can help improve your overall sleep. You can try a relaxing bedtime yoga routine or journaling.
  • Skip late naps - Napping after 3:00 p.m. can interfere with your sleep cycle and keep you awake at night. 
  • Stick to a regular sleep schedule - Inconsistent wake-up times — waking up at 7:30 on a Thursday morning and then sleeping in until noon on Saturday — wreaks havoc on your circadian rhythm.
  • Use Pillow to help you maintain a regular sleep schedule where you go to bed and wake up at the same time each day.  

Final Thoughts on the Sleep Cycle  

Each of the four stages of your sleep cycle is important. Moving through each of these four stages is essential for restorative sleep. If you are waking up mid-sleep cycle after trying the above tips for at least a week or having a hard time falling asleep, talk to your doctor to determine if you need other help, such as a referral to a sleep specialist. 


Written by

Emily Mendez

Emily Mendez is a former therapist and mental health author. She is one of the leading voices in mental health. Emily's writing has appeared in eCounseling, SonderMind, and more. Emily is frequently interviewed by Healthline, Fatherly, INSIDER, Family Circle, and other national media for her advice and expert opinion on the latest mental health topics.

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