REM, non-REM, deep sleep, light sleep, awake — there are just so many terms that are thrown around when it comes to sleep that it’s easy to get them mixed up. Of course, the most common mistake most people make is thinking that REM sleep and deep sleep are the same things.
Right now, you’re probably a little shocked by that bombshell. But, yes, REM sleep and deep sleep are completely different stages of the sleep cycle — just like, say, light and deep sleep.
So, what exactly is the difference between REM and deep sleep? Or, rather the differences?
Well, that’s the question that we’ll be tackling today. But, first, let’s have a brief introduction to the four stages of sleep — just so that we have a little bit of a context before we proceed further.
The four different stages of sleep
In general, there are two basic types of sleep: rapid eye movement (REM) and non-REM sleep. The latter has three different stages — stage 1, stage 2, and stage 3 (also known as deep sleep). REM sleep is Stage 4. You will cycle through all four stages several times a night.
First things first, let’s talk briefly about stage 1. This is also known as N1 and normally lasts only about one to five minutes. Here, the body isn’t fully relaxed but the body and brain activities do start to slow down.
Meanwhile, with stage 2, the body enters deeper into sleep. This is where the body will see a drop in temperature, relaxed muscles, as well as much slower breathing and heart rates.
Stage 2 can be anywhere from 10 to 25 minutes and gradually becomes longer. Most people spend about 50% of the entire sleeping time in this stage.
But, of course, today our focus isn’t on these stages. Instead, we’re zooming in on REM and deep sleep. So, let’s get to that.
What’s REM sleep?
Now that we know the different stages of sleep, let’s talk about REM sleep. This is the deepest sleep stage and most people experience REM sleep about 90 minutes after falling asleep.
In this sleep stage, your eyes will move much more rapidly in all directions. And, now you know how it got its name.
Here, your brain will see plenty of intense activities — with lots of dreaming of vivid dreams, recovery, memory and emotions processing, and more.
As for your body, there are a few changes. For starters, your heart rates and blood pressure increase during REM — usually to near awake levels.
But, here’s the interesting part: your body is largely inactive during REM. In fact, some resources have even called it a temporary paralysis of your arm and leg muscles due to the chemicals in the brain.
So, how long does REM last?
Well, there are different periods of REM sleep — anywhere from about three to five periods each night. The first period should last about 10 minutes or so. Then, each recurring REM stage lengthens. So, the final period of REM should be around an hour or so.
Then, what’s deep sleep?
Often confused for REM sleep, deep sleep is actually non-rapid eye movement (NREM) sleep. It’s the last stage of the non-REM stages. Deep sleep is also known as N3 (because it’s the third stage of sleep), slow-wave sleep (SWS), and delta sleep.
For most people on most nights, the body enters deep sleep somewhere from around 30 minutes to 45 minutes after falling asleep. During this stage of sleep, it’s almost a given that there will be no dreams.
While dreamless, this is the most difficult stage of sleep to wake up from. And, if you do wake up, you’ll feel disoriented and likely ready to murder whoever who woke you up.
Now, with REM, your body doesn’t see many activities. But, with deep sleep, there will be all sorts of changes in your body. For starters, your breathing and heart rates are stable here and should remain regular at this sleep stage.
Besides that, deep sleep is also when your body will heal itself. While you’re snoring away, there are all sorts of biological processes taking place here. For instance, cellular regeneration, repair of tissues and bones, growth of tissues, cellular rebuilding, and more. Oh, so much more!
That’s exactly why when you do get enough deep sleep, you wake up rejuvenated and ready to tackle the day. Otherwise, you’ll feel fatigued and without energy.
As for duration, deep sleep usually is about one to two hours each night. So that’s about a quarter of your entire sleeping time. However, do bear in mind that some people may need far more deep sleep than others.
REM and deep sleep: different but both vital
Now that we have nailed down the differences between REM and deep sleep, there’s something else worth remembering: the stages — including stage 1 and 2 — are all important for the overall health and well-being of your body and mind.
So, be sure to get a sufficient amount of sleep tonight.