Stages of Sleep

Breathing and Sleep Center of Colorado Springs

When thinking about sleep, most people focus on the duration of their sleep. While this is important, it’s only part of it. Sleep quality is also important. A critical component of high-quality rest is progressing smoothly through the four stages of sleep multiple times throughout the night.

Each stage in the sleep cycle is involved in allowing the mind and body to wake feeling refreshed. Learning more about the sleep cycle can help you understand how sleep-disordered breathing can impact the quality of your sleep as well as your overall health.  

If you are suffering from sleep apnea, the sleep doctors at the Breathing and Sleep Center in Colorado Springs can help. In this article, we’ll explain more about the stages of sleep.

4 Stages of Sleep

There are four stages in the sleep cycle:

  • Stage 1: Light sleep, lasts about 1 to 7 minutes  
  • Stage 2: Moderate sleep, lasts about 10 to 25 minutes
  • Stage 3: Deep sleep, lasts about 20 to 40 minutes
  • Stage 4: REM sleep, can last up to an hour

Stage 1

Stage 1 is when the body is transitioning from wakefulness to sleep. If someone is woken up during this stage, they will often say that they were not sleeping. During this stage:

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

This period lasts about 1 to 7 minutes. Your brain is still fairly active and producing high amp theta waves, which occur primarily in the frontal lobe.

Stage 2

Approximately half of your total sleep time is spent in Stage 2, which lasts about 10 to 25 minutes per cycle. During this stage:

  • You’re less aware of surroundings
  • Body temperature drops
  • Eye movements stop
  • Breathing/heart rate regulate

Your brain begins producing sleep spindles, which are a type of memory consolidation, where your brain gathers, processes, and filters new memories acquired during the day.

This stage is preparing your body for Stage 3 and REM sleep.

Stage 3

Stage 3 is when delta waves begin to emerge, and any environmental noise/activity will usually fail to wake up the sleeping person. This is the stage where sleepwalking occurs and is most common during the early part of the night. During this stage:

  • Muscles are relaxed
  • Blood pressure drops
  • Breathing slows
  • You progress into deepest sleep
  • Your body begins physical repairs

You feel refreshed the next day if you spend enough time in Stage 3 sleep. This is when your brain will consolidate declarative memories, such as facts/statistics, general knowledge, and other things you’ve learned.

Stage 4

Stage 4 sleep, also known as REM sleep, is when your brain is aroused but your voluntary muscles are immobilized. During this stage, your brain’s activity is very similar to when you are awake, but since your body is paralyzed, you do not act out your dreams.

This stage typically begins about 90 minutes after you fall asleep. During this time:

  • Your brain is active
  • Your body is relaxed/immobile
  • Breathing is fast and irregular
  • Eyes move rapidly
  • You dream

Memory consolidation involving emotions occurs during this stage and your brain cements things to your memory, which makes this stage critical for learning.

Sleep Better with Help from the Sleep Doctors at Breathing and Sleep Center

If you are not getting the rest you need, you may be suffering from sleep-disordered breathing. One of the most common sleep disorders is sleep apnea. Let the sleep doctors at Breathing and Sleep Center in Colorado Springs help. We offer alternatives to traditional methods of surgery and CPAP for treating sleep apnea. Call us today for your consultation.


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