0 comments

What are the stages of sleep?

Sleep is traditionally divided into four categories: awake sleep, light sleep, deep sleep and rapid eye movement sleep (REM). Each plays an important role in keeping your body and mind healthy.

When you fall asleep, your brain cycles through four sleep stages.

Stages 1 to 3 are considered non-rapid eye movement (NREM) sleep, also known as quiet sleep.
Stage 4 is rapid eye movement (REM) sleep , also known as active sleep or paradoxical sleep.

Each has a unique function and role in maintaining the brain's overall cognitive performance. Certain stages are also about body repair, keeping you healthy and ready for the next day.

The entire sleep cycle repeats several times each night, with each successive REM stage increasing the duration and depth of sleep.

This article explains the basics of the sleep cycle, what happens when each sleep stage occurs, and what factors can affect your ability to move through these stages the way you should.

Go to sleep

Using electroencephalography (EEG), a non-invasive test that records brain activity, scientists were able to see how the brain performs various mental activities while a person is falling asleep and asleep.

During the initial stages of sleep, you are still relatively awake and alert. At this point, the brain produces so-called beta waves - small, fast brain waves that mean the brain is active.

When the brain begins to relax and slow down, it emits alpha waves. During this transition into deep sleep, you may experience strange and vivid sensations called hypnotic hallucinations.

Common examples of this phenomenon include the sensation of falling or hearing someone calling your name.

There are also myoclonic jerks; if you've ever been suddenly startled for no apparent reason, you've experienced this.

NREM Phase 1

The first stage of the sleep cycle is the transition between wakefulness and sleep. If you wake someone during this stage, they may report that they didn't really fall asleep.

During stage 1 sleep:

your brain slows down
Your heartbeat, your eye movements, and your breathing slow down
Your body relaxes and your muscles may twitch

This short period of sleep lasts about 5 to 10 minutes. At this time, the brain is still quite active and produces high-amplitude theta waves, which are slow brain waves that occur primarily in the frontal lobes of the brain.

NREM Phase 2

According to the American Sleep Foundation, people spend about 50% of their total sleep time during NREM stage 2, with each cycle lasting about 20 minutes.

During stage 2 sleep:

You become less and less aware of your surroundings
your body temperature drops
your eye movements stop
Your breathing and heart rate become more regular

The brain also begins to produce rapid, rhythmic brain wave activity, which are called sleep spindles. They are thought to be a feature of memory consolidation—when your brain collects, processes, and filters new memories you acquired the day before.

When this happens, your body slows down to prepare for NREM stage 3 sleep and REM sleep—the deep sleep stages when the brain and body repair, restore, and reset for the day ahead.

NREM Phase 3

During NREM stage 3 sleep, deep, slow brain waves called delta waves begin to appear, and this stage is also called delta sleep. This is a period of deep sleep, and any noise or activity in the environment may not wake the sleeping person. Getting enough NREM stage 3 sleep can help you feel refreshed the next day.

During NREM stage 3 sleep:

your muscles are completely relaxed
your blood pressure drops and your breathing slows down
you enter the deepest sleep

It is during this deep sleep stage that your body begins to repair itself.

At the same time, your brain consolidates declarative memories—for example, general knowledge, facts or statistics, personal experiences, and other things you've learned.

REM sleep

When your brain is awakened by mental activity during REM sleep (the fourth stage of sleep), your voluntary muscles become immobilized.

It is during this stage that your brain activity most closely resembles your waking activity. However, your body is temporarily paralyzed - which is a good thing, since moving prevents you from dreaming.

REM sleep begins approximately 90 minutes after falling asleep. at this time:

Your brain lights up with activity
Your body relaxes and settles
Your breathing is faster and more irregular
your eyes move quickly
you dream

As in stage 3, memory consolidation also occurs during REM sleep. However, REM sleep is thought to be when emotions and emotional memories are processed and stored.

Your brain also uses this time to consolidate information into memory, making it an important stage in learning.

sequence of sleep stages

It's important to realize that sleep does not go through the four stages in perfect order .

When you have a full night of uninterrupted sleep, the stages progress as follows:

Sleep begins with NREM stage 1 sleep.
NREM Phase 1 enters NREM Phase 2.
NREM Phase 2 is followed by NREM Phase 3.
Then repeat NREM Phase 2.
Finally, you enter REM sleep.

Once REM sleep ends, the body usually returns to NREM stage 2 before starting the cycle again.

The time spent in each phase changes throughout the night as the cycle is repeated (about four to five times in total).

Sleep architecture refers to the exact cycles and stages a person goes through during a night. A sleep specialist may show you this information through what's called a hypnogram (a graph generated by an electroencephalogram).

What can interrupt your cycle

Disrupted sleep is the term used to describe sleep that is not continuous throughout the night. When this happens, your sleep cycle may be disrupted. In progress sleep stages may be shortened and the cycle may repeat before completion. There are many issues that can interrupt your sleep cycle. Depending on which one is at work, this may happen occasionally or chronically. Some factors that are associated with sleep disruption and therefore may affect your sleep stages include:

Old age: Sleep naturally becomes lighter and easier to wake up.
Nocturia: Frequently waking up to need to urinate
Sleep disorders , including obstructive sleep apnea (stopping and starting breathing during sleep) and restless legs syndrome (a strong sensation of needing to move the legs)
Pain: Difficulty falling asleep or staying asleep due to an acute or chronic pain condition (such as fibromyalgia)
Mood disorders, such as depression and bipolar disorder
Other health conditions , including Alzheimer's disease, Parkinson's disease,10 obesity, heart disease, and asthma
Lifestyle habits: Little/no exercise, smoking, excessive caffeine intake, excessive alcohol consumption

generalize

As your body goes through the four stages of the sleep cycle, it goes through different biological processes that affect your body temperature, breathing, cells, and muscles. All the time, your brain is busy forming, organizing, and storing memories. Over time, not getting enough sleep and cycling through the four stages of sleep can lead to health problems and difficulties with:

Study and focus
creative
make rational decisions
Solve the problem
recall memory or information
control your emotions or behavior

very good sentence

It's important to not only get seven to nine hours of sleep each night, but also to ensure uninterrupted quality sleep so that your body benefits from each of the four stages.

Make an appointment to see your healthcare provider if you experience any of the following, as you may not be getting the sleep you need:

You have trouble falling or staying asleep at least three nights a week
you often wake up feeling uneasy
Your daytime activities are affected by fatigue or mental alertness
You often need to take a nap to get through the day
Your sleep partner tells you that you snore or gasp while sleeping
Lack of sleep is affecting your mental health

frequently asked questions

What is REM sleep?

Rapid eye movement (REM) sleep is the fourth stage of sleep. During this stage, brain activity increases to levels similar to when you are awake and leads to vivid dreams. The brain temporarily paralyzes major muscles, preventing us from moving while we dream.
How much REM sleep do you need?

There are no specific recommendations on how much REM sleep you need. This is because REM occurs in multiple intervals of varying lengths of time. However, most adults should try to get at least seven to nine hours of sleep each night.
How long is each sleep stage?
- NREM Phase 1: Less than 10 minutes, begins immediately after falling asleep
- NREM Phase 2: Lasts 30 to 60 minutes
- NREM Phase 3: Lasts 20 to 40 minutes
- REM sleep: The first stage of sleep is about 10 minutes, then gradually lengthens over time
How long is a sleep cycle?

A complete sleep cycle usually lasts about 90 to 110 minutes. After a sleep cycle is complete, the process starts over again and repeats until we wake up.