Stages of Sleep: What Happens During Sleep?



Sleeping is a fascinating part of our daily routine that many do daily without understanding, and understanding sleep is very important. Your brain takes a crazy roller-coaster ride through stages of sleep each night while your consciousness is entirely unaware.

The good night’s sleep is separated into stages of sleep, and each stage of sleep plays a different role in how rested you are and how you feel the next day.

What Are the Four Sleep Stages and What Does Each Sleep Stage Do?

Sleep has been traditionally divided into four different stages of sleep and those sleep stages are awake, light, deep, and REM sleep.

Each one of these stages of sleep is important, and each of the sleep stages plays an important role in maintaining your mental and physical health. Each one of the sleep stages is worth understanding and getting to know.

NREM Stage 1

You are still somewhat alert as you are drifting off into comfortable sleep. During this stage of light sleep, you will probably be quickly startled by small noises or movements, as well as aware of your surroundings. 

As the brain begins to relax more and more, it produces Alpha waves, sometimes called “quiet wakefulness.” During Stage N1, you might experience strange sensations; falling, for example.

In this stage of sleep, muscle tension decreases, and eye movement and brain wave activity slow down. Once the muscles are fully relaxed, muscle spasms or hypnic jerks can be experienced. This stage of sleep usually lasts five to ten minutes.

NREM Stage 2

During this stage of sleep, the brain waves will continue to slow down, and eye movement is going to decrease.

Stage two of sleep lasts for about thirty to sixty minutes, allowing you to gradually become more and more unaware of your surroundings and less likely to wake up to small noises or movements.

The body temperature and heart rate will continue to drop, and your muscles will continue to relax and release tension.

NREM Stage 3 – Deep Sleep stage

Stage 3 is also commonly referred to as “deep sleep,” and it lasts between twenty to forty minutes. During the deep sleep stage, the brain cleanses itself of toxins, which is why the deep sleep stage is considered to be the most restorative of all four stages of sleep.

Some important things that happen to your brain and body during the deep sleep stage include:

  • the body is fully relaxed
  • non rapid eye movement
  • delta brain waves are present
  • immune system strengthens
  • tissue repairs and grows, and cell regeneration occurs

REM Sleep

REM sleep is the primary “dreaming” stage of sleep, and rem sleep occurs about ninety minutes after you fall asleep. Stage R rem sleep lasts for about ten minutes the first time, increasing with each REM cycle.

Some of the changes that happen during the rem sleep stage include:

  • rapid eye movement
  • heart rate and breathing increases
  • heart rate and breathing become more variable
  • brain activity is increased
  • muscles become paralyzed, but muscle twitches can occur

Sleep Disturbances

Different disorders can affect the quality and quantity of sleep you are getting on a nightly basis. Some of the most common sleeping disturbances include:


Insomnia is a chronic sleep disorder, and its main characteristic is having trouble falling and staying asleep.

Some people who have insomnia have trouble falling asleep, while others cannot stay asleep, while the least lucky ones have trouble with both. Insomnia can often cause fatigue and excessive daytime sleepiness.


Narcolepsy is one of the neurological disorders of the chronic central nervous system, and it causes extreme daytime sleepiness.

Narcolepsy is also characterized by uncontrollable sleep attacks during the day, along with poor or no sleep at night.

One type of narcolepsy, also called Type I narcolepsy, can also cause cataplexy, an uncontrollable loss of muscle control that causes physical collapse of the whole body.

Sleep apnea

OSA (short for obstructive sleep apnea) is one of the most common sleep disorders that cause the body to stop breathing during sleep. These periods of no breathing are called apnea, and they can happen because the throat airways narrow down, obstructing the airflow, making it difficult or impossible to breathe. 

Shift work disorder

Shift work disorder is one of the sleep disorders which is commonly observed in those that do not work the regular 9-to-5 hours. This disorder often appears when a person’s working hours do not align with the natural sleeping pattern and rhythm.

Tips and tricks to fall asleep and improve sleep quality

Falling asleep can be difficult sometimes, and knowing helpful tips and tricks to help you drift off faster can be very useful, especially in those situations where you cannot help but think about the alarm that is about to go off in a few hours.  Some helpful tips to help you fall asleep faster include:

  • Getting exercise during the day, at least a few times a week
  • Staying off your phone before going to bed
  • Keeping the bedroom cool
  • Sleeping on a high-quality, firm, comfortable mattress
  • Practicing yoga, stretching, and meditation before going to bed
  • Reading or listening to relaxing music before going to bed
  • Avoiding food for a few hours before going to bed
  • Having a warm bath or shower before going to bed


Your body cycles through all of the above-explained stages of sleep every night. Different thighs are affected and changed during these sleep cycles, including muscles, breathing, heart rate, and brain waves.

Good sleep hygiene is non-negotiable, as uninterrupted sleep and quality sleep are essentials for health-promoting activities such as focus, growth, digestion, and memory. Certain sleep disorders, such as insomnia, can cause sleep deprivation, and sleep deprivation can cause difficulty functioning throughout the day because they cause poor sleep quality that affects all daily activities.

The best thing you can do to improve your sleep quality is to address any underlying conditions and work on your sleep hygiene.