Sleep: How it Works

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Introduction

Sleep is vital for healthy living and life, just like eating and breathing.  Sleep allows your body to rest.  During sleep, your muscles and tissues grow and repair.  Researchers believe that during sleep your brain performs important functions, such as storing memory, solving problems, and processing brain chemicals.  Brain chemicals and hormones help keep your immune system healthy and regulate your appetite.  A good night’s sleep is necessary for your body to recharge and revitalize so you can feel alert and productive the next day.

In a way, your body goes on “auto-pilot” while you sleep.  Your brain regulates automatic functions for you, such as breathing, heart rate, and blood pressure.  The average adult needs about eight hours of sleep.  Babies, children, and teenagers need more.  Although sleep is a complex process that is not fully understood, it is known that a good night’s sleep is important for optimal health, growth, and functioning.

Sleep is a step-wise process that is regulated by the brain.  Sleep consists of a series of cycles of about 90 minutes in duration.  Each cycle consists of several stages.  The stages and cycles are repeated several times during the night. 

Stage 1
You feel drowsy and your eyes are closed during step 1.  Your brain lets your body know that you are getting ready to sleep.  This stage of sleep is short, lasting about 5 to 10 minutes.

Stage 2
You sleep lightly during Stage 2.  Your body temperature drops and your heart beats slower.  Your body is preparing for deep sleep.

Slow Wave Sleep
Formerly known as Stages 3 and 4, Slow Wave Sleep is the deepest stage of sleep.  Your blood pressure lowers and your muscles relax and undergoes a process of restoration and re-energizing.  Dreaming first occurs in this stage.

Stage REM
REM stands for the “rapid eye movements” that take place while your eyes are closed.  Your heart and breathing rate may increase.  This is the stage of sleep in which vivid dreaming occurs.  Your body is relaxed and immobile.  The first REM stage of the night is the shortest and occurs about 90 minutes after sleep onset.  The REM periods become longer with each repetition of the full sleep cycle.
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This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.

The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on February 16, 2022. For information on iHealthSpot’s other services including medical website design, visit www.iHealthSpot.com.