We hear a lot about REM.

It’s the sleep that we should all aspire to, experts say. It’s why short afternoon naps can often drain us, rather than regain us. It’s when our body fully shuts itself down, to get some much-needed rest.

But what exactly is REM, or Rapid Eye Movement? And is it really as important as everyone says?

Let’s start with the facts.

What is REM sleep?

Basically, the sleep that we get every night can be divided into two categories: non-REM sleep, and REM sleep. And there’s a good chance you know the difference.

Non-REM sleep is what we know as napping, or dozing off. It’s those first 90 minutes of sleep that can feel a bit more lucid. Phase I usually takes place in the first 15 minutes, when we can still be easily woken up by someone or something. Phase 2 is light sleep, as our bodies prepare for a deeper rest; at this point in the sleep cycle, both your body temperature and heart rate lessen. And then Phase 3 of non-REM rests is a deep sleep, which, when woken up from, can be temporarily disorienting. (Hello, long afternoon naps!)

Then we move onto REM sleep, which takes place after about 90 minutes. This is the sleep we mostly associate with our at-night rest when we sleep for hours on end. Its name derives from the fact that underneath our eyelids, our eyes are darting around fast, back and forth. And we’re not the only ones who do it — REM sleep is common amongst most mammals.

There are different phases of REM sleep, which can typically last anywhere between 10 minutes and an hour. Our heart rate rises, our breathing quickens, and with more brain activity comes vivid dreaming. It’s sleep, in all senses of the word.

So why do you need REM sleep then?

It goes back to the simple question: why is sleep itself important? Because not only does our body need rest, but also, it needs time to actually recover. Throughout the day, our body zaps energy, proteins, and other vital necessities, through physical movement and mental focus. It’s why you feel drained, for example, after a long day of work. What REM sleep essentially does is activate the brain, and help it re-develop those synergies. It’s when that rebuilding process really begins.

In addition, dreaming is like a treadmill for your brain. It’s healthy to enter a deep dream state, as it signifies your brain is functioning at a normal level. In other words: every night when you reach REM sleep, your brain is essentially hitting the gym, recouping from the day.

The experts are right: REM sleep is the sleep you should be aiming for. If you’re restless at night, then you’re not allowing your body to reach that redevelopment stage, which means it’s missing out on all the benefits of REM sleep. That’s why your brain likely feels fuzzy the next day at the office — it didn’t get to hit the gym, and blow off some steam. And that’s also why naps aren’t the answer; they’re short-changing your brain and body from the sleep you deserve.

Natural supplements like Dream EZ are often cited as sure-fire ways to reach REM sleep.  They allow your body to comfortably ease past the non-REM phases, and into that higher stage of relaxation and redevelopment that is so important when you’re striving to accomplish your goals. In the end, it’ll leave you feeling more energized and focused when you wake.