Stages of Sleep: What Goes on When You’re Not Awake?
Sleep is sleep, as long as you’re getting enough of it, right? Not necessarily.
Your body goes through different stages of sleep each night – so your sleep at 10 p.m. is probably not the same as your sleep at 4 a.m. We know that sleep is important for our health and allows our bodies to grow and restore themselves. But, have you ever thought about goes on when we’re not awake? We decided to delve into the sleep stages and discover what really happens while we’re catching our Zzz’s.
Stages of Sleep
There are five phases of sleep that we all pass through every night: stages 1 through 4 and rapid eye movement (REM). Sleep progresses in cycles that begin with stage one and goes through REM sleep, and repeats itself throughout the night. While half of our sleep cycle is spent in stage 2, about 20% of our time is in REM sleep and 30% in the other stages. Every stage is important, but some stages have more energizing effects than others.
Stage 1: During stage 1, our bodies are in light sleep and can be easily awoken during this stage. We tend to drift in and out of sleep as our eyes move slowly and muscle activity reduces. Many of us experience sudden muscle contractions called hypnic myoclonia, or the falling sensation accompanied by sporadic jolts as we’re dozing off.
Stage 2: As we enter stage 2, eye movement stops and our brain waves slow down. We become disengaged from our surroundings, breathing and heartrate are regular and our body temperature drops as we prepare for deep sleep.
Stage 3 and 4: In these stages, our slowest brain waves – called delta waves – begin to appear and we enter our deepest, most restorative sleep. Our blood pressure drops, our breathing slows down and our muscles relax. During these stages, hormones are released to promote growth and muscle development. Energy is restored and tissue growth and repair occurs. Typically, it’s very hard to be awoken during this stage and doing so may leave us feeling groggy and disoriented.
Stage 5: REM sleep is the final stage before repeating the cycle. During this stage, breathing becomes more rapid, irregular and shallow, and our eyes jerk rapidly in different directions. Limbs become immobile and relaxed as our brains send messages to our spinal cords that temporarily paralyze us. Our brains are most active during REM sleep and we enter the dream world – although we may not remember every dream we have.
The first REM stage usually lasts about ten minutes, and each stage gets longer, and as the final one can last up to an hour.
Know Your Sleep
It’s important to know about our sleep stages as losing sleep during any of these critical periods inhibits our ability to retain information and form memories. For tips to sleep happy, check out Dr. Kansagra’s Sleep 101: The Basics of Sleep Hygiene and make sure you’re maximizing every minute of your shut eye!