Stages of Sleep
When thinking about getting the sleep you need, it’s normal to focus on how many hours of sleep you get. It’s also critical to think about sleep quality and whether the time spent sleeping is actually restorative. Understanding the sleep cycle helps explain how certain sleep disorders, including insomnia and obstructive sleep apnea can impact a person’s sleep and health.
What Is the Sleep Cycle?
Over the course of a night, your total sleep is made up of several rounds of the sleep cycle, which is composed of four individual stages.
- In a typical night, a person goes through four to six sleep cycles, lasting about 90 minutes each.
REM Sleep Patterns
During REM sleep, brain activity picks up to near the levels seen when awake
- At the same time, the body experiences atonia, a temporary paralysis of the muscles
- REM sleep is believed to be essential to cognitive functions like memory, learning, and creativity
- Dreams can occur in any sleep stage, but they are less common in the NREM periods
What Affects Sleep Stages?
Age
- Time in each stage changes dramatically over a person’s life
- Newborns spend far more time (around 50%) in REM sleep and may enter a REM stage as soon as they fall asleep
- As they get older, their sleep becomes similar to that of adults, normally reaching a comparable sleep architecture by the age of 511.
- Recent sleep patterns
- If a person gets irregular or insufficient sleep over a period of days or more, it can cause an abnormal sleep cycle
How Can You Have a Healthier Sleep Cycle?
Focus on improving your sleep hygiene
- Achieving a more consistent sleep schedule
- Getting natural daylight exposure
- Avoid alcohol before bedtime
- Eliminating noise and light disruptions can help you get uninterrupted sleep and promote proper alignment of your circadian rhythm
Stage 2 / N2
During stage 2, the body enters a more subdued state including a drop in temperature, relaxed muscles, and slowed breathing and heart rate
Are All Sleep Cycles the Same?
The first sleep cycle is often the shortest, ranging from 70-100 minutes, while later cycles tend to fall between 90-120 minutes.
- In addition, the composition of each cycle – how much time is spent in each sleep stage – changes as the night goes along.
Stage 3 / N3
Also known as deep sleep, this stage is critical to restorative sleep, allowing for bodily recovery and growth. Muscle tone, pulse, and breathing rate decrease as the body relaxes further.
- Deep sleep contributes to insightful thinking, creativity, memory, and deep sleep cycles.
Why Do the Sleep Stages Matter?
Sleep stages are important because they allow the brain and body to recuperate and develop. Failure to obtain enough of both deep sleep and REM sleep may explain some of the profound consequences of insufficient sleep on thinking, emotions, and physical health.
What are the Sleep Stages?
There are four sleep stages: rapid eye movement (REM) sleep, non-REM sleep, delta sleep, deep sleep, and deep sleep
- Stage 3 NREM N3, Slow-Wave Sleep (SWS), Delta Sleep, Deep Sleep 20-40 minutes
- These stages are determined based on an analysis of brain activity during sleep
Stage 1 / N1
This is essentially the “dozing off” stage, and it normally lasts just one to five minutes.
- During N1 sleep, the body hasn’t fully relaxed, though the body and brain activities start to slow with periods of brief movements (twitches).