You need to get enough sleep each night to feel your best each day. But how much sleep do you need exactly?
Unfortunately, there’s no magic number that works for everyone. We all need a different amount of sleep and this amount changes over our lifespan, and it can even change from night to night, depending on our health, how sleep deprived we are, and what we’ve done with our days.
Luckily, there are a few ways you can find out how much sleep you need.
Below, we’ll cover what science says about how much sleep is best, and how you can use the RISE app to work out how much sleep you need and get it more easily.
“Everyone needs a different amount of sleep each night. Seven to nine hours of sleep is a good starting point, but if you feel tired during the day, you may need more sleep than that,” says Dr. Chester Wu, who 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.
Most adults need about 7.5 to nine hours of sleep. Babies, children, and teens need even more. But the amount of sleep you need is highly individual. As one paper on the topic states, “there is no “magic number” for the ideal duration of sleep.”
The amount of sleep you need is called your sleep need. It’s genetically determined, just like height and eye color.
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Scientific studies have similar findings. One study worked out the sleep needs of adults aged 20 to 26. The mean sleep need was eight hours 25 minutes. But, again, there was a range. Sleep needs ranged from seven hours 17 minutes to nine hours 16 minutes.
For an exact number, RISE can tell you how much sleep you need in hours and minutes.
The amount of sleep you need will change depending on your age. According to the National Sleep Foundation, this is the recommended amount of sleep by age group:
These age-based sleep recommendations are useful, but they’re just guidelines. A 2018 paper states, “although sleep recommendations are a good tool for public health surveillance, they need to be adapted on a case-by-case basis in clinic (not a one-size-fits-all recommendation).”
These guidelines can be misleading, too. They come from studies looking at how much sleep people get, not how much they need, and they’re based on self-reported data, which research shows is often inaccurate.
For example, older adults may not need less sleep, despite many guidelines hinting that they do. Sleep becomes harder to get as we grow older. Studies show older adults get less sleep, so it’s assumed they need less.
Our sleep need data doesn’t back up that theory, though. For RISE users over 60, the median sleep need is eight hours and 18 minutes. For those aged 24 to 59, the median sleep need is eight hours and 24 minutes — a difference of only six minutes!
It’s not clear whether men and women need a different amount of sleep — more research needs to be done.
RISE user data shows the median sleep need for men is eight hours, whereas the median sleep need for women is eight hours 15 minutes.
They may need a similar amount, but women suffer from more sleep problems, so need more time in bed to get the sleep they need.
Women (and those assigned female at birth) are more likely to be diagnosed with a sleep disorder or an anxiety disorder, both of which make getting enough sleep harder. And your period, pregnancy, and menopause can all disrupt sleep.
We’ve covered more on whether women need more sleep here.
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The amount of sleep you need can change. While your sleep need is generally set from early adulthood, you may temporarily need more sleep if you’re recovering from illness, injury, intense exercise, or sleep deprivation.
A 2023 study found muscle injury causes a “significant increase” in total sleep time 48 hours and 72 hours post-injury. And another study found both deep sleep and overall sleep increased after participants completed a 92-kilometer race.
If you’ve lost out on sleep recently, you’ll have what’s known as sleep debt. Sleep debt is the amount of sleep you owe your body. If it can, your body may take the opportunity to catch up on lost sleep and sleep for longer when you’ve got sleep debt.
RISE can work out how much sleep debt you have, so you can tell if your body wants to sleep for longer to catch up.
And sometimes, the amount of sleep you need won’t change, but it may be harder to get it. For example, if you have a sleep disorder like sleep apnea, or anxiety rears its head, you may find yourself awake more in the middle of the night, and therefore have to spend longer in bed overall to reach your sleep need.
You can work out how much sleep you need by waking up without an alarm for one or two weeks or by downloading the RISE app.
Here’s how these two methods work:
Try waking up without an alarm for at least a week, but ideally two weeks. Keep a sleep diary and write down when you fall asleep and when you naturally wake up. This can give you an idea of how much sleep you need.
This method of finding out your sleep need is called the “sleep rebound” method.
There are a few problems with this method:
The quicker, easier, and more reliable way of finding out your sleep need is by using the RISE app. The app uses a year’s worth of your phone use behavior and proprietary sleep-science-based models to work out your sleep.
RISE acts as a sleep calculator, telling you how much sleep you need down to the minute.
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There’s no one best time to go to sleep. When you should go to sleep will depend on how much sleep you need, your morning commitments, and your chronotype (whether you’re an early bird or night owl).
Here’s how to figure out when you should go to sleep:
For example, if you need seven hours of sleep a night and need to get up at 7 a.m., you’d count back and find you need to be asleep by midnight. Add on 30 minutes or so to fall asleep, and now you know you should go to bed at around 11:30 p.m.
Another factor to think about is your chronotype, or whether you’re an early bird, night owl, or somewhere in between. An 11:30 p.m. bedtime is all well and good, but if you’re an extreme night owl you may struggle to fall asleep at that time.
The best bedtime for you would be one that matches your chronotype. But if this isn’t possible, you can reset your sleep schedule to shift your natural sleep-wake times earlier or later to fit your lifestyle. We’ve covered how to reset your sleep schedule here.
To take the guesswork out of bedtime, check RISE for your Melatonin Window each night. Your Melatonin Window is the roughly one-hour window of time when your body’s rate of melatonin production is at its highest.
Melatonin is the hormone that primes your body for sleep, so heading to bed during this time will give you the best chance of falling asleep easily. If you go to bed any earlier, you may find yourself lying awake in bed.
You can also use RISE’s smart schedule feature to find your ideal bedtime. Tell the app when you want to wake up and it’ll give you a goal bedtime based on your sleep need and whether you need to catch up on any sleep.
You should wake up at a time that gives you enough time to get the sleep you need, fits with your chronotype, and is one that you can wake up at consistently.
You should also try to give yourself 60 to 90 minutes in the morning before you need to be “on.” This is because of sleep inertia, or that groggy feeling we all get right after waking up. So, if you start work at 9 a.m., a 7:30 a.m. wake-up time may be best for you.
To perfect your wake-up time, think about your chronotype, or when your body naturally wants to wake up and go to sleep. If possible, choose a wake-up time that fits with your natural tendency. RISE will show you your “Wake Zone,” or the time your body naturally wants to wake up.
If that time is too late for your life (night owls may struggle if they have early work hours or kid duties), try resetting your circadian rhythm (your body clock) to change your natural wake-up time.
Need to wake up earlier? We’ve covered how to become a morning person here.
RISE’s alarm feature can help find the best time for you to wake up. The alarm tells you — as you’re setting it — whether your chosen wake-up time will add to your sleep debt or not. If it does, you can choose to set a later alarm time, if possible, or strive to head to bed earlier the next night.
Heads-up: You may have heard that to find the best time to wake up you need to think about sleep cycles. These are the roughly 70-to-120-minute cycles of sleep we move through several times each night.
There’s a common idea that the best time to wake up is at the end of a sleep cycle. But sleep cycles aren't as clear-cut as people think. They look different from person to person and can change shape and length throughout the night.
Our advice? Don’t worry about sleep cycles. Instead, focus on having a wake-up time that allows you to meet your overall sleep need.
There are four stages of sleep: stage 1, stage 2 (light sleep), stage 3 (deep sleep), and stage 4 (REM sleep).
These four stages make up one sleep cycle. A sleep cycle lasts about 70 to 120 minutes. And you may get four to six sleep cycles a night, depending on how much sleep you need.
Here’s what happens in each sleep stage:
When it comes to how much sleep you need, we argue you don’t need to worry about light sleep, deep sleep, or REM sleep. There’s only one number you need to focus on: your overall sleep need.
That’s because your brain is very good at self-optimizing and spending the right amount of time in each sleep stage for you. To make that happen, all you have to do is get enough healthy sleep from good sleep hygiene (more on that soon).
For more advice on this, we’ve covered how much REM sleep you need here and how much deep sleep you need here.
It’s important to get enough sleep because sleep deprivation can lead to low energy, trouble concentrating, impaired memory, lowered athletic performance, poor mood, weight gain, mental health issues like depression, low sex drive, bad skin, and high blood pressure — just to name a few.
If you don’t get enough sleep, you’ll be more likely to fall asleep while driving, get sick, and suffer from serious long-term health issues, like obesity, diabetes, and cardiovascular disease.
And there’s plenty of science from the last year alone backing up those scary facts. A 2023 study found there’s a 27% increased risk of infection in those who get less than six hours of sleep.
And another 2023 study found sleeping for six hours or less was associated with higher odds of having a medical condition, including diseases of the nervous system, musculoskeletal system, digestive system, and circulatory system.
A 2022 study found sleeping for five hours or less a night at ages 50, 60, and 70 was linked to a high risk of multimorbidity, or having two or more chronic diseases like cancer or heart disease.
The signs of not getting enough sleep include:
You may not notice the effects of sleep deprivation, however, as we grow used to the feeling of a lack of sleep.
One study found participants were largely unaware of their mental performance getting worse with sleep deprivation. And another study found participants thought they were well-rested, but slept for more than three hours more than usual when they got the chance.
You may also think you’re getting enough sleep (if you don’t know your sleep need, for example), but really be falling short, so you’re always sleepy.
To get enough sleep, improve your sleep hygiene. These are the daily sleep habits you can do to get a good night’s sleep.
Here’s what to do to improve your sleep hygiene:
It’s not just how much sleep you get. You also want your sleep to be quality sleep, which means healthy and naturalistic sleep that’s not too fragmented (interrupted throughout the night). Luckily, improving your sleep hygiene helps with improving sleep overall, too.
With good sleep hygiene, you’ll fall asleep faster, wake up less often, and get the natural sleep you need for good health and wellness.
To stay on top of your sleep hygiene and sleep better, RISE can tell you when to do 20+ sleep hygiene habits each day at the time that makes them the most effective for you.
We all need a different amount of sleep, and this changes depending on our age and whether we’re recovering from illness, injury, intense exercise, or sleep loss.
Instead of relying on guesswork and guidelines, turn to the RISE app to find out how much sleep you need. RISE uses algorithms and your phone use data to work out your individual sleep need down to the minute.
RISE can also tell you how much sleep debt you have, the best times to sleep and wake up, and guide you through 20+ sleep hygiene habits to make meeting your sleep need easier.
See the benefits fast — 80% of RISE users feel more energy within five days.
Most healthy adults need about 7.5 to nine hours of sleep. Babies, children, and teens need more. The amount of sleep you need is highly individual, however, and you may need more sleep if you’re recovering from illness, injury, intense exercise, or sleep deprivation.
Most women need about 7.5 to nine hours of sleep, which is the range for most adults. More research needs to be done to find out if women need more sleep than men. Women are more likely to have a sleep disorder or anxiety disorder, and they may have trouble sleeping because of their menstrual cycle, pregnancy, or menopause, so they may need longer in bed to get the sleep they need.
Most adults need about 7.5 to nine hours of sleep. The amount of sleep you need is highly individual, however, and you may need more sleep if you’re recovering from illness, injury, intense exercise, or sleep deprivation.
Newborns need 14 to 17 hours of sleep, infants need 12 to 15 hours, toddlers need 11 to 14 hours, preschoolers need 10 to 13 hours, school-age children need nine to 11 hours, teenagers need eight to 10 hours, and adults need 7.5 to nine hours. These amounts are guidelines, however, and the amount of sleep you need is highly individual.
More research needs to be done to find out the minimum amount of sleep needed for brain function. Although your brain may be able to function on little sleep, research shows your memory, focus, decision-making skills, and mental performance will all be lower if you don’t get enough sleep. Most adults need about 7.5 to nine hours of sleep for maximum brain function, but this number is different for everyone.
There’s no set amount of sleep that’s too much because everyone needs a different amount of sleep each night. Plus, it’s hard to sleep for too long. You may sleep for longer than usual when you’re recovering from injury, illness, intense exercise, or catching up on lost sleep. Speak to a doctor if you’re regularly sleeping for more than 10 hours.
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