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What Happens When You're Asleep

It’s National Sleep Awareness Week and most of us aren’t getting enough sleep. We’ve written before about the importance of sleep, healthy sleeping tips, and ways to promote better sleep.


We’ve all heard that we spend about one-third of our lives sleeping, but it’s hardly unproductive time. Rather sleep plays a crucial restorative role in our lives. Our quality of sleep determines how full, energetic and successful we are in the other two-thirds of our lives.

Better sleep helps us thrive by contributing to a healthy immune system, and can also balance our appetites by helping to regulate levels of the hormones ghrelin and leptin, which play a role in our feelings of hunger and fullness. When we’re sleep deprived, we may feel the need to eat more, which can lead to weight gain.In addition, levels of the hormone cortisol dip at bed time and increase over the night to promote mental sharpness in morning.

Here’s exactly what happens when you sleep:


Sleep follows a pattern of alternating REM (rapid eye movement) and NREM (non-rapid eye movement) sleep throughout a typical night in a cycle that repeats itself about every 90 minutes.

NREM (75% of night): As we begin to fall asleep, we enter NREM sleep, which is composed of four stages:

Stage 1

  • Between being awake and falling asleep
  • Light sleep

Stage 2

Onset of sleep

  • Becoming disengaged from surroundings
  • Breathing and heart rate are regular
  • Body temperature drops (so sleeping in a cool room is helpful)

Stages 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

IdealVitamins Staff
IdealVitamins Staff

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