Sleep Stages…. Zzzzzzz…. What are these? How does this really affect me?
Ok, let’s take a look at what happens when we sleep..
What is REM and NREM Sleep? What is happening in my body at each stage?
Sleep is made of non rapid eye movement (NREM) sleep and rapid eye movement (REM) sleep.
NREM is made of four levels:
Stage 1: this is the beginning of the sleep cycle, when the lights are off and your close your eyes, your brain waves slow down and so does your breathing and heart rate. Muscles start to relax. Transition from wakefulness to light sleep. 5% of the time. If woken you wouldn’t have thought you were asleep.
Stage 2: Slightly deeper sleep than stage 1, you can still wake easily in this stage. This may feel like you’re falling, you may even wake up, or become less aware of your environment. 40-50% total sleep time. I always have a strange feeling that I’m falling down stairs or have jumped out of a plane without a parachute.
Stage 3 and 4 sleep: deep sleep or delta sleep account for 20% sleep time. Our deepest level of NREM and usually occurs in the first third of the night. In this stage, our blood pressure drops more, muscles become more relaxed, blood flow decreases. The growth hormone is excreted into pituitary gland in deep sleep, and the body heals itself, you experience repair and tissue regeneration, physical restoration of sleep. When you get enough delta sleep you wake feeling refreshed.
REM sleep takes place during the last 3rd of night and makes 25% of sleep time. During REM sleep, there are small variable speed brain waves, rapid eye movements like those that occur during your wakeful state. Voluntary muscles are paralysed (heart lungs, are all active). This stage your body restores its nervous system, processes information and store memories. Getting enough REM sleep you think more quickly, creatively and organise thoughts better.
What are the sleep cycles that occur during the night?
After you fall asleep, a normal sleep cycle can take you from light into deep sleep back into light sleep and then onto REM. After REM your body awakens briefly and then returns to stage 1 sleep to repeat process. Throughout the night you cycle through the sleep stages, with REM sleep increasing in length with each cycle and deep sleep decreasing toward the morning. To feel fully refreshed you need ample amounts of each sleep cycle.
How long does each sleep cycle last?
Each sleep cycle lasts 90 minutes. For sleep to be restorative you need several sleep cycles every night (usually 4 or 5)
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