How Much Deep Sleep Do You Need Each Night?

No matter how hard we try, it can seem like we can never get enough sleep. It could be that sleep eludes us, and we spend the night tossing and turning. Or there aren't enough hours in the day to do everything we need, so we find ourselves sacrificing sleep to make up the difference.

In either case, though, not getting the rest we need can have major consequences. And it's not just a matter of how much sleep do we need, but getting enough of the right kind of sleep, too. In particular, you want to know how much deep sleep do you need to function at your best.

To better understand the importance of sleep, let's take a look at the role it plays, how much we need, and what happens when we don't get enough of it.

What Happens While We Sleep?

They say that we spend about a third of our lives asleep. That may sound like a lot of time doing nothing, but make no mistake — we're far from sitting idle while we rest each night.

During sleep, both body and mind are busy running a series of background tasks that help maintain our health and wellbeing. For instance, you may have heard that getting enough rest is vital to staying healthy and that without it, you can get sick.

That's because sleep is the period where the immune system refreshes itself. Though you may be dreaming, it's hard at work producing cytokines and antibodies — two crucial disease-fighting agents. If you're skipping sleep for whatever reason, your immune system can't replenish its supply of these agents, and you can expect more sick days in your future.

It's also during sleep that your body repairs itself. If you sustain an injury and don't give yourself ample time and rest, your body will never get the chance to do the repair work that needs to be done.

Meanwhile, the brain is working overtime as well.

While we sleep, the brain gets the chance to process the events of the previous day. That's one theory for the often surreal things that we can experience in our dreams; their side-effects of the brain sorting through and processing our memories and emotions.

So sleep plays a role in plenty of essential functions. But not only do we need rest, but the right kind of rest.

It's Not Just a Matter of How Much Sleep Do You Need, but the Quality as Well

As it turns out, not all sleep is created equal. Like many bodily processes, sleep happens in phases, each of which plays a role.

To better understand how each step works, here are the four stages of sleep:

Stage One

Stage one is the point at which you're drifting between wakefulness and sleep. It's sort of the twilight stage.

At this point, you're only sleeping very lightly. You may shift into a relaxed state and even start to dream. But you may also toss, turn, and twitch. Particularly as you transition from this brief stage into stage two.

Stage Two

At this stage, you are still in a light sleep. However, you're shifting into a steadier period in the process.

Here your muscles should be relaxed, as your pulse and breathing slow. Your brain activity also lessens as you slide further into unconsciousness.

Stage Three and Four

Stage three and four are very similar, as, by this point, you are in a deep sleep. All of your vitals, your body temperature, and your brainwaves are at their lowest points by the time you reach this state.

Your muscles will be extremely relaxed, and someone would have the most difficult time rousing you awake at this point.

Stage four is also sometimes called the healing stage. No longer tied up with having to deal with conscious activities, your body can focus on activities like repairing damage and rebuilding the immune response. Because of these vital functions, this stage is the most important stage.

Getting the Right Amounts of Each Type of Sleep

Based on that information, it would stand to reason that the only stage that really matters is stage four, right? Because of all of its functions, if you can get into that deep, restful state, you should be fine?

Well, it's not quite that simple.

Unfortunately, there's still a lot about sleep that science just doesn't know yet. Some researchers believe that light sleep experienced in stages one and two is just as important as the deep sleep of stages three and four. We definitely know that even light sleep can yield refreshing effects, as anyone who's taken a satisfying nap can attest.

However, the verdict is still out. And because you would normally have to go through those stages to attain deep sleep anyway, there is no daily recommended amount that you would need to attain.

But there is an interesting component that we have not yet mentioned that merits discussion.

What About REM Sleep?

REM sleep is sometimes called the fifth sleep stage, though that's not necessarily accurate. More what it is, a cycle that repeats itself several times during a night's sleep. The first one takes place around 90 minutes after you fall asleep, with subsequent REM cycles taking place at 90-minute intervals.

During these cycles, the eyes dart around rapidly beneath the eyelids. Hence the name; REM is short for Rapid Eye Movement.

Meanwhile, your brainwaves, heart rate, and breathing are elevated to near the levels that they would be while awake. This is also the period where you are most likely to dream.

The purpose of REM sleep is not well understood. Experts theorize that dreaming helps the mind to process thoughts, memories, and feelings that we've experienced throughout the day. If true, then REM sleep seems to encourage dreaming would mean that it plays an important role in that process.

How much REM sleep should you get then? Well, as with light sleep, there's no official recommendation.

What we do know is that for most adults, REM cycles make up some 20-25% of the time we spend sleeping.

This appears to be consistent with a healthy sleep pattern, but there are still things that we don't know and questions that are raised. For example, research points to a correlation between the larger amounts of REM sleep and depression, but the nature of this link is still unclear.

So How Much Deep Sleep Do You Need?

What we do have a reasonable understanding of is the role that deep sleep plays in our physiology and how much of it we need by extension.

In a healthy adult, about 13 to 23 percent of the sleep they take will be deep sleep. So if you sleep for the recommended eight hours per night, that breaks down to between 62 and 110 minutes.

But that's just a rough estimate. Generally speaking, the older we get, the less deep sleep we require.

Teens, for instance, are recommended to sleep between eight and ten hours per night. Meanwhile, some adults can get by on as little as six with no ill effects.

In any event, getting enough sleep becomes less of a matter of setting bedtimes and setting yourself up to sleep properly.

If I'm Getting the Recommended Amount, Why Do I Still Wake Up Tired?

It's possible to sleep eight hours and still wake feeling tired and irritable. You've probably experienced it more than once in your life. But how and why does this happen.

Well, though you may be sleeping at all of the right times, you're likely not falling into a deep enough sleep to wake up feeling refreshed and revived.

Causes could be something as simple as the temperature. Research has demonstrated a link between the ambient temperature in a sleeping area and the quality of sleep that an individual is likely to have. Specifically, the study seems to suggest that cooler environments are more conducive to consistent, restful sleep.

Caffeine is another cause. While coffee can have health benefits, many of us over-indulge. If restful sleep eludes you, it might be wise to cut out that afternoon pick-me-up.

Another common cause could be over-exposure to blue light. This is a recent phenomenon, as the blue light that's naturally emitted by the sun would be insufficient to cause problems on its own.

But what does emit blue light in abundance is technology. Fluorescent light bulbs, LED screens, and smart devices all bombard us with blue light.

This becomes a problem because humans should only be exposed to the blue light of the sun. Our bodies, then, associate it with daytime and wakefulness. By basking in the blue light of devices all night, we're throwing off our bodies' natural rhythms and making it difficult to fall asleep and stay asleep.

How to Get Into a Deeper Sleep

To get enough deep sleep at night, you need to put yourself in a position conducive to falling asleep and staying asleep long enough to reach that fourth stage. There are certain do's and don'ts to follow if you want to achieve that quality rest.

Program Yourself to Sleep at a Certain Time

For starters, it's helpful to set a strict bedtime. The main reason for this is that it builds routine, both consciously and unconsciously.

Consciously, if you know that you need to be in bed by, say, 11 pm, it will help you budget your time to make that achievable. Instead of staying up to stream one more episode of your favorite show, you can be crawling into bed with enough spare time to account for how long it will take to drift off.

And unconsciously, you're programming your body as well. We're meant to run on a day and night cycle. So by consistently falling asleep around the same time each night, your signaling to your body that that time of night means sleep, and it will naturally want to power down around that hour.

On that note, try to avoid those afternoon naps. As tempting as they may be, they can wreak havoc on your natural rhythm. All the work spent programming your body to fall asleep at a certain time can be undone by a little after-work snooze.

Declutter Your Mind

Aside from upsetting your sleep cycle, the next most common culprit is the inability to get your mind to quiet down.

That's why the effects of blue light aside, it's a good idea to avoid screens before bed. TV, the internet, and the like all keep the mind abuzz instead of letting it slide into a relaxed state. Even reading less than half-an-hour before bed can help keep you awake.

Instead, spend the time before bed running, cultivating a mental relaxation habit that works for you.

De-Stress

Despite your best efforts, excess stress can help keep you awake. Besides keeping your mind too busy to relax, stress triggers the release of the hormone cortisol.

Cortisol is the fight-or-flight hormone intended to help us survive intense situations. As such, it doesn't mix well with a good night's sleep.

Normally, it would drop to its lowest levels around midnight, consistent with a state of deep rest and relaxation. So when levels are high, you're odds of sleeping well are reduced.

To counteract this, learn a stress management technique that works for you. Breathing exercises, mindfulness training, and meditation techniques are all tried and tested methods of reducing stress.

Rest Well for Optimal Health

Doctors and researchers all seem to agree on sleep's importance to our health. In particular, achieving enough deep sleep is vital to give our bodies enough time to refresh and repair. Without it, we leave ourselves vulnerable to injury, illness, and a plethora of other issues.

Knowing how much deep sleep do you need is a great first step towards attaining greater overall health. Once you can achieve it reliably, you may notice that you feel more energized, have greater mental clarity, and suffer fewer sick days.

For more tips on how to not only get enough sleep but increase its quality as well, check out our guide on how to get better sleep.