How Much Deep Sleep Do You Need? A Sleep Scientist Explains

Deep sleep helps with everything from recovery to memory to strengthening your immune system — not to mention helping us feel rested the next day. But how much deep sleep do we need exactly? 

Unfortunately, it’s not a simple answer. We all need a different amount of deep sleep a night. And that amount can change from night to night, too. Sleep experts don’t even have set guidelines for deep sleep as it’s constantly changing and individual. 

The good news is you don’t need to worry about it. Your brain can self-optimize and spend the right amount of time in deep sleep each night — all you need to do is get enough healthy sleep overall. 

Below, we’ll dive into how much deep sleep you need and how you can get more of it. Plus, we’ll share how the RISE app can help you get the right amount of deep sleep for you by getting enough sleep each night.

Advice From a Sleep Doctor

“There’s no set number when it comes to how much deep sleep you need," says Dr. Chester Wu. "What we do know is that your brain will automatically adjust how much time you spend in deep sleep each night based on your current needs. Focus on getting enough sleep each night, and you’ll get enough deep sleep, too.”

Dr. Chester Wu is double board certified in Psychiatry and Sleep Medicine, and provides sleep medicine services, medication management, and psychotherapy to adults at his private sleep medicine and psychiatry practice.

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You spend about 10% to 25% of your time asleep in deep sleep. That means if you need eight hours of sleep, you’d need 48 minutes to two hours of deep sleep. But, unfortunately, it’s not as clear-cut as that. 

There are no agreed-upon guidelines for deep sleep as it changes so much from person to person and from night to night. 

Plus, not everyone needs eight hours of sleep. Our sleep needs — the genetically determined amount of sleep we need — are all different. And therefore the amount of deep sleep you need will be different, too. 

Our sleep need findings: We looked at sleep need data from 1.95 million RISE users aged 24 and up and found the median sleep need is eight hours. But our users’ sleep needs range from five hours to 11 hours 30 minutes. 

To make things more complicated, you don’t spend the exact same amount of time in deep sleep each night. A 2023 study found the percentage of time participants spent in deep sleep (as well as light sleep and REM sleep) changed over the course of five nights. 

And you may need more sleep overall some nights, like when you’re ill. 

We asked one of our sleep reviewers, Dr. Jamie Zeitzer, who’s the co-director of the Center for Sleep and Circadian Sciences at Stanford University, for his thoughts.

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Turn to the RISE app to find out how much sleep you need overall. RISE uses proprietary sleep-science-based models and a year’s worth of your phone use behavior to work out your sleep need down to the minute. 

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Children need more sleep than adults, so they may need more deep sleep, too. Research shows children get significantly more deep sleep than teenagers and adults. And we get less deep sleep as we age.

According to the National Sleep Foundation, here’s how much sleep you likely need based on your age: 

• Newborns: 14 to 17 hours 
• Infants: 12 to 15 hours 
• Toddlers: 11 to 14 hours 
• Preschoolers: 10 to 13 hours 
• School-aged children: 9 to 11 hours 
• Teenagers: 8 to 10 hours 
• Young adults and adults: 7 to 9 hours 
• Older adults: 7 to 8 hours 

Heads-up: Older adults may not need less sleep. Sleep is harder to come by as we age, and this may be reflected in generic sleep need guidelines, which are based on surveys that look at how much sleep people get — not what they actually need.

When we looked at our own sleep need data, the median sleep need for RISE users over 60 was 8 hours 18 minutes. The median sleep need for those aged 24 to 59 was 8 hours 24 minutes — a mere six minutes longer. 

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We argue you don’t need to know how much deep sleep you need. 

Here’s why: 

• Your body knows what it’s doing: Your brain works hard to make sure it spends the right amount of time in deep sleep, as well as every other sleep stage. You don’t need to do anything but make sure you’re getting enough sleep overall.  
• You can’t control it: You can’t command your brain to get more deep sleep, so why worry about it? 
• You can’t accurately measure it: At-home sleep trackers that tell you how long you spend in different sleep stages are mostly inaccurate. It’s hard to tell if you’re getting enough deep sleep or not without getting a polysomnography (PSG), or a sleep study, done in a lab. And even then, sleep experts only agree on test results about 80% of the time.
• More research needs to be done: There’s still a lot we don’t know about sleep, including how much deep sleep we need exactly and how to get more of it. 
• You should have good sleep hygiene anyway: Most of the behaviors you can do to get more deep sleep (more on those soon) are part of sleep hygiene, the sleep habits you should be doing each day to get a good night’s sleep — even when you’re not thinking about deep sleep. 
• Every sleep stage is important: Deep sleep sounds like the most restorative stage, but every sleep stage plays an important role in your health and energy levels. Don’t neglect REM and light sleep in your effort to get more deep sleep.
• Deep sleep isn’t the most important metric: Research from Dr. Zeitzer shows the amount of deep sleep you get isn’t associated with subjective sleep quality. Instead, track your sleep debt. Sleep debt is the measure of how much sleep you owe your body and has the biggest impact on how you feel each day. Rather than worry about deep sleep, focus on sleep debt to make the biggest difference to your health and energy levels.

Our top piece of advice: If you want to get more energy, be more productive, boost your mood, or improve your mental and physical health, the best thing you can do is focus on getting enough sleep each night and keeping your sleep debt low. 

The good news? Get the right amount of sleep and your brain will do the hard work for you and get the right amount of deep sleep (as well as light and REM sleep). We demystify all things sleep quantity vs sleep quality here.

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Each night of sleep is made up of four different stages of sleep: three stages of non-rapid-eye-movement sleep (NREM sleep) and one stage of rapid-eye-movement sleep (REM sleep). 

Once you’ve moved through all four sleep stages, you’ll complete one sleep cycle. Each sleep cycle lasts about 70 to 120 minutes and, depending on the number of hours of sleep you need, we get four to six sleep cycles a night. 

Here’s how a night of sleep should go: 

• Stage 1: This stage only lasts for a few minutes as you first drift off. You’re in a light sleep, so you can easily be disturbed by something like a loud noise. You may spend 2% to 5% of the night in stage 1. 
• Stage 2: In stage 2, also known as light sleep, your breathing, heart rate, and brain activity all begin to slow down and become more regular. This stage can last from 10 to 25 minutes in the first sleep cycle and you get progressively more light sleep with each cycle. You may spend 45% to 55% of the night in stage 2. 
• Stage 3 (deep sleep): In stage 3, or deep sleep, your breathing and heart rate slow down even more and your brain activity produces delta waves. The deep sleep phase can last from 20 to 40 minutes in the first sleep cycle, and will progressively decrease over the course of the night. In fact, it’s common to not go into deep sleep after the second cycle at all. You may spend 10% to 25% of the night in the deep sleep stage. 
• Rapid eye movement (REM): This is the stage most known for when you dream. Your eyes can be seen moving rapidly under your eyelids — hence the name. Most of our muscles are paralyzed during the REM stage to stop us from acting out our dreams. REM sleep may only last one to five minutes in the first cycle, and it gets longer and longer with each cycle. You may spend 20% to 25% of the night in REM. 

Heads-up: How your sleep is structured is known as sleep architecture. And sleep architecture is not the same for everyone and it can even change from night to night. Your sleep cycles can change in length and shape throughout the night, and the boundaries between sleep stages can be fuzzy. 

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Deep sleep is one of the stages of sleep we move through each night.

During deep sleep, also known as slow wave sleep, your brain activity produces patterns of slow brain waves (hence the name) known as delta waves. Your heart rate and breathing slow down, and experts believe deep sleep is when the most recovery takes place. 

Deep sleep is the hardest stage to wake someone up from. And if you are woken up from deep sleep, you may feel more groggy compared to waking up in light sleep. 

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Deep sleep is vital for rest and recovery. In this stage, your immune system is strengthened, your brain detoxified, and your pituitary gland secretes growth hormone, which helps cells in the body regenerate and repair. 

Deep sleep is also the sleep stage where your brain works on creating and storing memories and consolidating new information you’ve learned during the day. Research suggests deep sleep may even play a part in processes like glucose metabolism.

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The best way to get more deep sleep is to get enough sleep overall. That’s because we can’t control how our brains move through the different sleep stages. 

What we can do, however, is make sure we get enough healthy natural sleep each night with good sleep hygiene (more on that soon). When we get enough sleep, our brains will self-optimize and spend the right amount of hours in deep sleep. 

Use RISE to find out how much sleep you need and then aim for this number each night. 

Here are our top tips to help you do that, and how these activities affect deep sleep: 

• Cut yourself off from caffeine about 12 hours before bedtime: Caffeine can last for 12 hours or more in the body, so skip the afternoon coffee or switch to decaf to avoid having trouble falling asleep come bedtime. And avoid after-dinner coffee or desserts with caffeine, research shows caffeine before bed can decrease deep sleep. 
• Exercise, but not within an hour of bedtime: A 2021 study found exercising can improve the stability of deep sleep. Just be sure to avoid intense workouts within an hour of bedtime as these can keep you awake, which may lead to less deep sleep. 
• Avoid alcohol three to four hours before bed: Research shows even small doses of alcohol can decrease how much deep sleep you get.
• Take time to wind down before bed: Among RISE users, stress and anxiety are the biggest barriers to a good night’s sleep. And stress can mess with your deep sleep. To help, have a bedtime routine where you engage in relaxing and non-stimulating activities, like reading or yoga, to help you wind down before bed. 

These behaviors are part of something called sleep hygiene, which are the daily habits you can do to get a good night’s sleep. To help you get enough sleep (and enough deep sleep) each night, RISE can guide you through 20+ sleep hygiene habits each day. 

Here are some key habits to focus on to help you get enough sleep overall: 

• Get bright light first thing: This resets your circadian rhythm (your body clock) for the day, helping to keep your sleep cycle on track. Research shows bright light exposure and early first light exposure are both linked to more deep sleep.  
• Avoid bright light in the evening: Light suppresses the sleep hormone melatonin, making it harder to fall asleep. Dim the lights and put on blue-light blocking glasses at least 90 minutes before bed. 
• Take a warm shower or bath before bed: This will help you relax. Plus, a 2019 meta-analysis found a warm shower, bath, or foot bath increased deep sleep. A 2023 study found foot baths are also effective at decreasing your core body temperature, which can help you drift off.  
• Keep a consistent sleep schedule: For better sleep, try to wake up and go to sleep at the same time each day, even on weekends. Regular sleep patterns can help you fall asleep on time each night and get enough sleep overall, so you get enough deep sleep. RISE users with low sleep debt have more consistent sleep-wake times than those with high sleep debt. 

Want more deep sleep tips? We’ve covered more on how to get more deep sleep here.

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Stress, pre-bed caffeine, and alcohol can lead to less deep sleep, and those with depression and sleep apnea may get less deep sleep. 

Speak to your healthcare provider if you think a mental health issue, medical condition, or sleep disorder is stopping you from getting enough (deep) sleep.

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Not getting enough deep sleep can affect immune function, skin health, and even your ability to retain information properly. Not to mention you simply won’t be feeling or performing your best. Plus, a lack of deep sleep has been linked to serious health problems such as high blood pressure, heart disease, stroke, and Alzheimer’s disease. 

After a night of total sleep deprivation, the next time you go to sleep, you’ll spend less time in stages 1, 2, and REM sleep, and more time in deep sleep, which experts say shows just how vital this phase of sleep is. 

After a night of partial sleep deprivation — think six hours or fewer — you’ll spend less time in stages 1, 2, and REM, but deep sleep may be less affected (depending on the time you went to bed) as this mainly happens in the first few cycles of sleep. But that doesn’t mean this kind of sleep deprivation is okay. 

You’ll be throwing off the balance between the sleep stages, your daytime performance will keep getting worse and worse until you get enough sleep, and sleep studies show you’ll be increasing your risk of developing everything from type 2 diabetes to cancer.  

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You spend 20% to 25% of your time asleep in REM. So, if you need eight hours of sleep, you’d need 1 hour 36 minutes to two hours of REM sleep a night. 

This number will be different for each of us, though, as we all need a different amount of sleep each night. And there are no definitive guidelines as the amount of REM we need varies so much from person to person and from night to night. 

We’ve covered how to get more REM sleep here.

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You spend 45% to 55% of your time asleep in light sleep. So, if you need eight hours of sleep, you’d need 3 hours 36 minutes to 4 hours 24 minutes of light sleep. 

This number will be different for each of us, however, as we all need a different amount of sleep each night. There are no agreed-upon guidelines as the amount of light sleep we need varies so much from person to person and from night to night. 

Get Enough Sleep to Get Enough Deep Sleep 

Deep sleep should be about 10% to 25% of your overall sleep, but as everyone needs a different amount of sleep each night, the ideal amount of deep sleep looks different for each of us. And the amount of deep sleep you need can change from night to night, too.

If you want to improve your energy levels, health, wellness, and mood, focus on your total sleep time — and your deep sleep will follow. 

The RISE app can work out how much sleep you need each night and guide you through 20+ sleep hygiene habits to help you get it. 

And as 80% of RISE users get more sleep within five days, you could be hitting the right amount of deep sleep in no time.