The 4 Stages of Sleep and What They Do for Recovery

We are asleep for about 1/3 of our lives. This crucial time determines both the quality and the longevity of life. The body restores and recovers itself in many ways to maintain our mental health as well as daily physical functioning. Although previously broken up into 5 stages, experts have now combined stages 3 and 4. Take a look at the 4 stages of sleep and what they do to help restore the body:

 

Stage 1 – NREM (non-rapid eye movement)

• The light sleep that occurs between being awake and falling asleep where muscles relax
• Very slow theta waves are produced by the brain
• Approximately 5-10 minutes in length

Stage 2 – NREM

• The onset of sleep, we spend roughly 50% of our sleep time in this stage
• As we become disengaged from our surroundings, our brain waves slow down
• Breathing and heart rate are regular
• Body temperature begins to drop
• Approximately 20 minutes in length

Stage 3  – NREM

• Deepest and most restorative sleep while the extremely slow delta waves are produced
• Breathing slows down as the muscles are more relaxed
• Blood supply to muscles increases
• Tissue growth and repair occurs
• Energy is restored
• Hormones are released – growth hormone
• Deep, slow delta waves are produced

REM (rapid eye movement)

• First occurs about 90 minutes after falling asleep and recurs about every 90 minutes resulting in roughly 20% of our sleep spent in this stage
• Provides energy to the brain and body, which then supports daytime performance
• Brain is active and dreams occur
• Body becomes immobile and relaxed, as muscles are turned off

During the non-REM sleep stages, tissue growth and muscle repair functions are signaled by the pituitary gland releasing growth hormones. In contrast, a lack of sleep will tell the sympathetic nerve system to release adrenaline hormones and signal the heart to work harder. This consequence of sleep deprivation is what poses an increased risk for high cholesterol, heart attack and stroke.

Sleep also helps balance our immune system. We are less likely to fight off the common cold when we are sleep deprived. Getting a regular full night’s rest will also help produce more antibodies and can even improve the benefits of preventative vaccines.

One of the more long-term implications of sleep recovery is how it can impact our memory. During sleep, the brain is in the most ideal state to consolidate processes that integrate new memories into our long-term storage. These are just a few of the many ways that our bodies utilize sleep as a time for healing.

 

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