How We Sleep

“There is a time for many words, and there is also a time for sleep.” — Homer


Sleep, like food and water, is essential for humans to survive. Sleep affects almost every type of tissue and system in the human body. The brain, heart and lungs perform functions while you sleep. Similarly, your metabolism and immune system perform functions while you are sleeping. Sleep also affects your mood and ability to resist and fight diseases. Research shows that a chronic lack of sleep, or getting poor quality sleep, increases the risk of cardiovascular disease, diabetes, depression, and obesity. The next day you feel exhausted, tired, or fatigued after a poor night’s rest.


What is sleep?

All night long, humans’ cycle in and out of two forms of sleep, REM and non-REM sleep. REM means rapid eye movements. During REM sleep your eyes dart back and forth behind your eye lids.


  •   Non-REM Stages. Sleep begins at the non-REM stages of N1 and moves sequentially to the N2 stage and N3 stage. The stages are then reversed, changing to N2 stage, following the N3 stage, and returning back to the N1 stage. At night, most people will repeat this cycle about four times.


During Non-REM sleep, your brain becomes less responsive to the outside world and it gets harder to wake up on command. During this stage, at N2 in particular, most thoughts and body functions slow down and you think of long-term memories.


  •   REM Stages. During the REM stage your pulse, body temperature, breathing, and blood pressure rise to daytime levels. This is the stage where dreams occur. You will feel active and have vivid thoughts. However, your body remains still and asleep. The brain activity in this stage mimics brain activity when you’re awake.


  •   Sleep Cycles. At night, you will experience all stages of sleep. How long you remain in each stage depends on you. Certain sleep disorders, like obstructive sleep apnea, affect whether or not you enter a sleep stage. The deepest sleep and body repair occurs during REM sleep.


Why REM sleep is so important

During deep sleep, your body repairs and resets itself. It is during REM sleep that muscles, organs, and other cells get to work to repair damage from the day or from chronic illnesses. The immune system takes off and circulates chemicals to strengthen it and fight off disease. The brain also processes and indexes the information of the day – clearing out information that is not needed and retaining important information or memories. While you sleep your body also makes hormones. Hunger hormones need sleep to stay consistent. Interrupted sleep may mean weight gain because your hunger signals are off. As we age, it feels harder to get restful sleep. The main reason for this feeling is that many individuals over the age of 65 never enter REM sleep.


Evaluating sleep

Talk to your doctor about evaluating your sleep. There is a nighttime and daytime sleep test that can show how you sleep and how long you remain in each sleep stage. By understanding where your sleep gets interrupted, you can make changes or use sleep aides to help your body get to rest. For more information about sleep, click here.

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