Understanding Stages of Sleep: A Comprehensive Guide
Sleep is more than the number of hours you spend in bed. Getting quality sleep helps with learning, memory, clearing toxins from the body, and is critical for overall health and well-being.
One way to think about the quality of sleep you get is to look at stages of sleep. There are four of them — the rapid eye movement (REM) stage, and three non-REM stages. Each one is important for your health. You need to spend enough time in each stage to make sure your sleep is restorative and you wake up feeling energized. You can do that by having good sleep habits.
Here, we’ll walk through the different stages of sleep, how sleep changes across the lifespan and some of the common sleep conditions.
NREM Stage 1
Stage 1 sleep, or light sleep, is the transition period between being awake and being asleep. This is the shortest stage of sleep, only 5% of your time in sleep. Here, brainwaves start to slow, muscles relax and your breathing becomes more regular. You can see brain waves during a procedure called an electroencephalography (EEG), which measures electrical activity in the brain.
It’s normal to experience involuntary muscle twitches or jerks during this stage as you start to drift off to sleep. These are called hypnic jerks and they’re sort of a misfire in your nervous system. While it can be annoying, it also doesn’t cause any harm.
NREM Stage 2
Stage 2 is when your heart rate and body temperature lower. This is right before your body enters deeper sleep. You spend the most time (45%) in this stage and as you get older, that time increases even more.
Sleep spindles occur in this stage that can be seen on EEG. These are short strong bursts of electrical activity in the brain and are important for being able to make and store memories. This stage of sleep is when you’re more likely to grind your teeth.
NREM Stage 3
Also known as slow-wave sleep or deep sleep, stage 3 is the deepest stage of sleep and the time when it’s the most difficult to wake up. But if you do, this is when you might feel the most disoriented, known as sleep inertia.
Deep sleep is the time when your body is restoring, repairing and healing itself. It’s also when your immune system is strengthened. You spend about 25% of your sleep in this stage and you tend to spend longer times in this stage earlier in the night.
Bedwetting, night terrors and sleepwalking can happen during this stage. Sleep issues in this stage can prevent some of those critical restorative functions from taking place.
REM Sleep
During rapid eye movement (REM) sleep, your skeletal muscles aren’t moving, except for your eyes rapidly moving back and forth and the muscles you use for breathing. REM happens about 90 minutes after you fall asleep, lasting about 10 minutes. Each cycle throughout the night gradually gets longer — up to an hour. You spend about 25% of your time in REM.
This is the stage of sleep where dreaming happens. Dreams have been part of the sleep cycle since recorded time: Fun fact — the earliest recorded dream was the dream of Dumuzi of Uruk, in the third millennium BC.
In REM sleep, brain waves look similar to when you’re awake, and the REM stage isn’t considered a restful stage of sleep. This is where sleep disorders like nightmares occur most often.
Sleep Cycles
These sleep stages cycle throughout the night — about four to six cycles — with each one lasting an average of 90 minutes. The time you spend in each sleep cycle changes as you get older.
Babies start out with three sleep cycles, though they spend half their sleeping time in REM sleep:
● Quiet sleep (similar to NREM)
● Active sleep (similar to REM)
● Indeterminate sleep
They cycle through these stages only one or two cycles a night. At about three months old, babies start having a circadian rhythm similar to adults.
Toddlers and children sleep less hours than babies, and spend less time in REM sleep, but still more than in teens and adults. Children spend more time in deep sleep. By age six, your child can develop a preference between being an early riser or a night owl.
Preteens and teenagers spend less time in deep sleep and more time in N2.Teens actually need more sleep than when they were younger for healthy brain development.
Older adults tend to have less deep sleep, have a harder time falling and staying asleep, and feel like they get more light sleep since they can wake up more abruptly.
Sleep Disorders and Sleep Stages
There are sleep conditions that can interrupt your sleep or keep you from getting the sleep you need. They can be from various factors like age or the brain not being able to fully pass through each sleep cycle.
Some of the more common sleep disorders include:
● Insomnia: A condition where you have difficulty falling asleep or staying asleep. This can happen more often in older adults.
● Sleep apnea: This is a breathing disorder where your breathing stops and starts many times throughout the night. Sleep apnea can keep you from getting enough deep sleep and REM.
● Restless leg syndrome (RLS): This is a condition where you have an urge to move your legs, and the symptoms get better with activity. RLS tends to happen in the lighter stages of sleep.
● Parasomnias: This is a group of sleep disorders that includes talking in your sleep, sleepwalking, sleep paralysis and night terrors. They’re categorized by REM and NREM parasomnias, depending on which stage of sleep they occur.
A Supportive Mattress for Quality Sleep
Sleep stages, and understanding the importance of spending time in each one, play a significant role in a healthy lifestyle. Prioritize sleep and work towards good sleep habits for everyone in the family.
And don’t forget where you sleep matters, too. Investing in a supportive, comfortable sleeping surface like a Brooklyn Bedding mattress and pillow, along with quality bedding, can go a long way in getting a restful night’s sleep.
