What is a book? NREM

For the first section of my book I have designed to write about different stages of sleep.
What happens when you sleep?

NREM

(75% of night): As we begin to fall asleep, we enter NREM sleep, wich is composed of stages 1-4.

STAGE 1

- Between being awake and falling asleep.
- Light sleep.

STAGE 2

- Onset of sleep.
- Becoming disengaged from surrounding.- Breathing and heart rate are regular.- Body temperature drops (so sleeping in a cool room is helpful).

STAGE 3 AND 4 


Deepest and most restorative sleep- Blood pressure drops.                                                 
- Breathing becomes slower.                                                                                                     - Muscles are relaxed.                                                                                                               - Blood supply to muscles increases.                                                                                         - Tissue growth and repair occurs.                                                                                             - Energy is restored.                                                                                                                   - Hormones are released, such as: Growth hormone, essential for growth and development, including muscle development.

REM 

(25% of night): First occurs about 90 minutes after falling asleep and recurs about every 90 minutes, getting longer later in the night.
- Provides energy to brain and body.   
- Supports daytime performance.                                                                                             - Brain is active and dreams occur.                                                                                           - Eyes dart back and forth.                                                                                                       - Body becomes immobile and relaxed, as muscles are turned off.