How Much Deep Sleep Do You Need, Really?

When it comes to getting a good night’s rest, the CDC (Centers for Disease Control and Prevention) recommends adults aim for seven to nine hours of sleep.

But how many hours of deep sleep do you need out of that total sleep time? Ideally, you want around 25 percent of your total sleep time to be deep sleep — which comes out to roughly one to two hours if you’re getting those seven to nine hours of shut-eye.

Now, it’s not always that simple. Getting the right amount of deep sleep can be tricky because many factors affect the quantity and quality of your sleep. So how much deep sleep do you need to hit the sweet spot for optimal health?

We’ll break down the different stages of sleep that make up a sleep cycle and explain what deep sleep really means.

Let’s dive in and explore how to make sleep as restorative as possible.

Your total sleep time — ideally about eight hours — is made up of a few cycles that are broken into stages. You can think of it as a journey with different stops, each playing a critical role in how rested you feel.

There are two deep sleep stages: deep sleep and deepest sleep.

The deepest stage of sleep — sometimes called slow-wave sleep or stage three of non-REM sleep (non-rapid eye movement) — is like the ultimate resting stop for your body and mind.

This stage is crucial for feeling refreshed and making sure your brain and body are ready to tackle the next day. Your brain is the least active during this third stage.

Or how much deep sleep is normal? On average, people get around 1.5 to two hours of stage-three sleep each night if they’re getting about eight hours of total sleep.

But the average deep sleep per night isn’t necessarily optimal.

Understanding deep sleep can be easier if you think of it as one part of a larger sleep cycle that includes other important stages. Each stage contributes to how well you rest and rejuvenate, so paying attention to all of them can help you improve your overall sleep quality.

People go through the different stages of sleep about four to five times each night. The combined stages of sleep comprise a sleep cycle. Every sleep cycle includes several key stages that fall into two categories: non-REM sleep (or NREM) and REM sleep.

Within NREM, there are three sub-stages, including light (N1), deep (N2), and deeper sleep (N3). There’s only one stage of REM sleep.

The four stages unfold in a sequence of light sleep, deep sleep, deeper sleep, deep sleep again, and then REM.

Each cycle lasts 90 to 110 minutes.

NREM Stages

The stages of non-rapid eye movement sleep include:

• Light sleep (N1)

• Deep sleep (N2)

• Deeper sleep (N3)

Let’s explore them in detail below.

Stage 1: Light Sleep (N1)

Stage one only accounts for about five percent of your total sleep time. It’s the moment right after you drift off to sleep and fade away from wakefulness.

Ideally, N1 should only take a few minutes. During this transitional stage, your breathing patterns are usually the same as when you’re awake.

Stage 2: Deep Sleep (N2)

Stage two accounts for about 45 percent of your total sleep time. In the first sleep cycle of the night, you spend just under 30 minutes in this stage. But as the night goes on, you’ll spend more time there, sometimes up to an hour each cycle.

During N2, your body really starts to relax — your heart rate slows down and your core temperature drops a bit. This helps your body to rest and recover effectively.

One cool thing about deep sleep is that it’s marked by something called “sleep spindles.” These are bursts of brain activity that play an important role in helping your brain form and consolidate memories. So, while you’re resting, your brain is busy sorting and storing all the things you’ve learned and experienced.

Getting enough time in this stage is crucial for waking up feeling refreshed and ready to take on the day.

Stage 3: Deepest Sleep (N3)

This is the deepest stage of sleep. It’s what we’re talking about when we mention deep sleep or slow-wave sleep (SWS).

Stage three is the hardest to wake up from, which is why you might feel groggy when disturbed during this time.

During N3, brain activity slows down significantly — this is when your body does its most essential repair work. Here’s what happens:

• Tissues repair and regrow.

• Bones and muscles are building and strengthening.

• Hormones are regulated.

• The immune system is maintained.

Typically, you spend 20 to 40 minutes in this stage during each sleep cycle.

There aren’t strict guidelines on exactly how much deep sleep you need. But if you spend half the night tossing and turning, it may point to a lack of deep sleep.

How Many Hours of Deep Sleep By Age Do You Need?

The amount of deep sleep you need can decrease with age. While the recommendation for adults through age 64 is usually seven to nine hours each night, for older adults over 64, aiming for seven to eight hours of shut-eye each night is usually recommended. The amount of deep sleep also naturally decreases with age.

REM Stage of Sleep

REM sleep is a unique stage of the sleep cycle where the brain becomes almost as active as when you’re awake. It’s the time when you’re most likely to experience vivid dreams.

During REM sleep, your brain is busy processing information and emotions from the day. It’s like your mind is sorting through everything that happened, helping you make sense of it all and prepare for the next day.

In the first sleep cycle, REM sleep starts out shorter, but it gradually gets longer as the night goes on. This means you’ll have longer periods of REM toward the end of your night’s rest.

Deep Sleep vs. REM

You might be wondering about the difference between deep sleep and REM.

As mentioned, deep sleep includes two stages: deep sleep and even deeper sleep, where your brain activity is quite low. In contrast, during REM sleep, your brain is very active — that’s one reason dreams are so vivid during REM sleep.

Interestingly, it’s much easier to wake up from REM sleep compared to the deeper stages of sleep, where you might feel groggy if interrupted.

Getting enough quality sleep, including sufficient REM sleep, is vital for overall health and well-being. If you’re not getting enough restful sleep, it can lead to sleep deprivation, which can affect your mood, energy levels, and overall functioning.

Some of the consequences of sleep deprivation include:

• Daytime sleepiness. This is the most obvious and common sign of sleep deprivation because it’s clear your body hasn’t had the chance to fully recharge. Feeling groggy throughout the day can also make it harder to do normal tasks and stay on top of responsibilities.

• Impaired function. People who consistently sleep only six hours a night (or fewer) are 33 percent more likely to get in a car accident than those who sleep seven or eight hours.

• Weakened immune system. One study found that folks who slept less than seven hours a night were almost three times more likely to get a cold than those who got more sleep.

• Increased risk of mental health conditions. Sleep and mental health are closely connected. If you’re feeling anxious or depressed, it might make it harder to sleep, and poor sleep can, in turn, worsen those feelings.

• Higher risk of heart disease. One study found that chronic sleep deprivation is associated with an increased risk for heart-related health conditions like heart disease, cardiovascular disease, and high blood pressure (hypertension).

• Potential for weight gain. Some research suggests a link between sleep problems and having a higher body mass index (BMI). One sleep study found that women who slept through the night without disturbances tended to have less body fat and more lean mass.

If you get less total sleep, you’re probably getting less deep sleep too. The good news is that by focusing on improving your sleep hygiene, you can likely improve your overall sleep quality and, thus, get more deep sleep.

Here are some helpful tips for getting a good night’s sleep:

• Stick to a consistent sleep schedule. Try to go to bed and wake up at the same time every day.

• Improve daytime habits. Regularly working out and cutting back on caffeine in the late afternoon can make a big difference in how easily you fall asleep at night.

• Upgrade your sleep environment. Create a restful space by using blackout shades or an eye mask to block out light and support your natural circadian rhythm. Investing in a supportive pillow and breathable bedding can also help.

• Put screens away. Limit your phone use to well before bedtime. Some research shows that the blue light screens emit might interfere with the sleep-wake cycle. It’s also just easy to lose track of time scrolling through social media.

• Practice stress management. Find relaxing activities or mindfulness techniques that help calm your mind before bed. This may make it easier to fall asleep and stay asleep.

• Use an alarm clock that wakes you up slowly. A less jarring alarm can help you wake up gently, which might make you feel more refreshed and less groggy in the morning.

• Try a white noise machine. Some people find that soothing background sounds can improve their sleep quality. The key is to choose sounds that help you stay asleep without disturbing your rest.

Taking small steps to improve your sleep patterns can lead to big benefits for both your overall health and your deep sleep.

Perhaps you’ve been following the tips for better sleep and still find that you’re not getting enough deep sleep. Or maybe you suspect your sleep issues are related to a sleep disorder like sleep apnea, restless leg syndrome, or another health concern.

Some research suggests that less stage N3 sleep can be a side effect of certain medications, including benzodiazepines, tricyclic antidepressants (TCAs), and barbiturates.

In any case, it doesn’t hurt to reach out to a healthcare provider for professional guidance.

They can help determine if there’s an underlying issue affecting your sleep, work with you on a treatment plan, or prescribe sleep medicine if needed. Your well-being is important, and getting the right support can make an immense difference.

When it comes to how much sleep you should aim for, everyone’s needs can be a bit different. But a good goal is seven to eight hours of total sleep each night.

Within that, it’s normal for most people to spend one to two hours in deep sleep, which is key for the body’s repair and recovery.

Here’s what to remember about how much deep sleep you need:

• Your night’s rest is divided into stages: light sleep (N1), deep sleep (N2), and deeper sleep (N3), followed by REM sleep.

• Deep sleep (N3) is crucial for repair and recovery, as well as overall health. Most people get one to two total hours of this stage of sleep. While important, it’s just one component of a good night’s rest.

• If you’re having trouble with sleep, focusing on better habits and creating a restful sleep environment can be really helpful.

• And if you suspect you might be dealing with sleep deprivation or other sleep issues, consult a healthcare provider.

If you have any concerns or need more personalized advice, don’t hesitate to reach out for support. Here’s to catching more Zs.

This article is for informational purposes only and does not constitute medical advice. The information contained herein is not a substitute for and should never be relied upon for professional medical advice. Always talk to your doctor about the risks and benefits of any treatment. Learn more about our editorial standards here.