Light sleep actually occurs in two stages: NREM stages 1 and 2 sleep.
Think of NREM stage 1 as “falling asleep.” During this time, your muscles relax, your heart begins to slow down, and your body temperature dips. Your brain waves slow down moving from a regular, rhythmic pattern to one with less frequent, less regular waves. Stage 1 sleep usually only lasts a few minutes.
NREM stage 2 sleep makes up the bulk of your NREM sleep. During this stage of sleep your muscles relax and may jerk. Your respiration and heart rate slow down. And your body temperature drops.
Associated with dreaming and memory, REM sleep plays an important role in re-energising your body. REM sleep makes up 5-50% of your total sleep and is regulated by your circadian rhythm. Typically you get more REM sleep in the second half of your sleep.
Deep sleep is the most restorative part of your sleep cycle. Deep sleep includes your normal sleep and your naps. Deep sleep can make up anywhere from 0-35% of your total sleep. On average the adult range is 15-20% which makes up 1-1.5 hours of deep sleep a night. This usually decreases with age. When you’re in deep sleep your blood pressure decreases, heart and breathing rates are steady and your muscles relax. During deep sleep, your muscles repair and grow which is why you often get more after a hard workout. Your immune system refreshes and your brain flushed out toxins. Normally deep sleep occurs mostly in the early stages of the night so try to get a consistent bedtime routine to help this occur to its best potential.
More on how to improve these cycles of sleep next week.