On our quest, my son Alek and I met more than a hundred longevity experts, and sleep came up almost everywhere. A nutritionist in New York put it first, before food. A doctor in Salt Lake City told us that sleeping again changed everything for her. A scientist in Singapore, answering a question from Alek, said seven to nine hours. And for a whole year the two of us shared small rooms, so we learned a lot about sleep ourselves. This page explains what we learned, in plain words. Every number has its source. Where science only shows a link and not a cause, we tell you.
This page shares what research and the experts we met say. It is not medical advice, and it does not recommend any medicine, supplement or treatment. It knows nothing about you. Before you start, stop or change anything — especially if you are pregnant, live with a health condition or take any medication — please talk to your doctor. In an emergency, call your local emergency number.
In short
Sleep is one of the best things you can do for a long, healthy life. While you sleep, your brain keeps what you learned, and your body resets its blood sugar and its defenses against germs. Adults who sleep enough, at regular times, die early less often, and heart doctors now count sleep among the eight essentials of a healthy heart. Cut it short for a few nights and your blood sugar suffers; give it back and your body recovers quickly. The best part: almost all of it is in your own hands. [1][2][3][4][5][6]
Longevity, as we mean it: more healthy, joyful years. What we mean →
7–9 hof sleep a night is what sleep experts and heart doctors recommend for adults.[7][6]
4×more likely to catch a cold, for people who slept six hours a night or less, when scientists gave them a cold virus.[3]
20–48%lower risk of dying early for people who sleep at regular times, compared with the least regular sleepers.[5]
If you sleep eight hours a night, you spend a third of your life asleep. That is not time switched off. It is one of the busiest things your body does. Everybody can sleep — but sleeping well is something you learn, and it is simpler than it sounds. That is the heart of this page: good sleep is a skill, and it is in your hands.
What sleep does for you
While you sleep, your brain sorts the day: it keeps what matters, so you can remember it tomorrow. Your body uses the night to reset. How well you handle sugar, how well you fight off germs and how you feel the next morning all depend on it. One short night you feel the next day. Short sleep for years shows up in long-term studies of the heart and the brain.
Sleep helps you remember
More than a century of research shows that sleep helps the brain hold on to what we learned during the day. Deep sleep and dream sleep (REM) each play their part.
Based on: A large review of research in people and animals [1]
A few short nights upset your blood sugar
Eleven healthy young men slept only four hours a night for six nights. Their bodies needed about 40% longer to bring blood sugar down after a meal, and they made and used insulin about 30% less well. After a week of long nights, everything came back to normal.
Based on: An experiment in people, in a sleep lab · shows cause [2]
In plain words: Sleep is not a luxury on top of a healthy life. It is part of the engine. And the good news from this study: when the men slept enough again, their bodies recovered quickly.
The brain cleans itself at night — so far seen in mice
In sleeping mice, the spaces between brain cells opened up by about 60%, and waste such as beta-amyloid — a protein linked to Alzheimer’s disease — was washed out faster than when they were awake.
Based on: One study in mice · not yet shown in people [8]
What studies in people show
Science answers this question in two ways, and it helps to know the difference. In a sleep-lab experiment, scientists change how long people sleep and watch what happens. That shows a cause, but only over days or weeks. In a long-term study, scientists follow large groups of people for years and see who stays healthy and who lives longer. That shows a link. Nobody can make thousands of people sleep badly for twenty years, so for the long run, links are what we have.
Too little sleep — and too much — goes with dying earlier
Across 16 studies of almost 1.4 million people, those who slept too little were about 12% more likely to die early. Those who slept very long were about 30% more likely. Very long sleep may often be a sign of an illness that is already there — scientists are still working this out.
Based on: Many long-term studies combined · a link, not proof [4][9]
Regular sleep may matter even more than long sleep
About 61,000 people in the UK wore a movement tracker on the wrist for a week. Those who went to sleep and woke up at regular times were 20–48% less likely to die early than the least regular sleepers, depending on how regular they were. Regularity predicted the risk better than the number of hours.
Based on: One big long-term study · a link, not proof [5]
In plain words: Going to bed and getting up at about the same time every day may be one of the simplest and strongest things you can do for your sleep.
Short sleep and catching colds
164 healthy adults wore a sleep sensor for a week. Then scientists put a cold virus into their noses. Those who had slept six hours a night or less were about four times more likely to catch the cold than those who slept more than seven.
Based on: One study in people · a strong link, not proof [3]
Short sleep in midlife and the brain later
About 8,000 British adults were followed from the 1980s until 2019. Those who regularly slept six hours or less in their fifties and sixties were about 30% more likely to develop dementia later than those who slept seven hours. The scientists say they cannot yet tell whether short sleep causes it.
Based on: One big long-term study · a link, not proof [10]
Heart doctors now count sleep
In 2022 the American Heart Association added sleep to its list of the eight essentials for a healthy heart, next to eating well, moving, not smoking, a healthy weight, blood pressure, cholesterol and blood sugar. For adults, it means seven to nine hours a night on average. [6]
What we don’t know yet
No fair test has yet shown that sleeping better makes people live longer — nobody can run one over decades. The numbers about dying early on this page come from long-term studies, and people who sleep well may also be healthier in other ways. The scientists say so themselves. Much of what we know about the brain cleaning itself at night comes from mice.
More years of life? Not yet tested in a fair test. The long-term studies show a link — a consistent one, but a link.
Is more sleep always better? No. The healthiest numbers sit in the middle, around seven to nine hours for adults. Whether very long sleep harms you, or is only a sign that something else is wrong, is still being studied.
Do you need to measure your sleep? A tracker can teach you about your habits. I wore one for a while, and what it taught me most was to stop worrying about my sleep. Nobody has shown that tracking on its own helps you live longer.
What our experts told us
We are deeply grateful to every expert who took the time to teach us. Here is what four of them said about sleep — and what it means for you.
“If you’re thinking autonomously and you’re not well-rested and it occurs to you that what you should do is go to the gym more often, you may not be exhibiting great common sense. Common sense would say that what you need to do is sleep and sleep with great efficiency, and find out what that is. […] So I would say that the most important thing of all, at least from my point of view, is you need to get your sleep in order.”
In plain words: Before you add more training or a better diet, look after your sleep. Everything else works better on top of it.
Amy Killen worked as an emergency doctor for ten years. Her shifts started at four in the morning, she was raising three small children, and she told us she was sleeping only a few hours a night. Then she changed her life.
“I sleep well. That’s actually been the thing that has changed the most. When I left the emergency room and was able to start sleeping again, it changed everything. All of a sudden, I lost 10 pounds that I didn’t need. My mood changed, my stress management changed. Like the sleep was such an important piece for me.”
In plain words: Sleep is not only about the far future. You can feel it in your mood and your stress long before any study about living longer would show it.
When Alek asked Guido Kroemer — one of the scientists behind the Hallmarks of Aging — what young people can do now, he answered with the basics.
“Well, I think there are some obvious lifestyle rules that you can apply even when you are just 20. […] Prepare your meals yourself, and sleep seven to nine hours per day.”
In plain words: Even top scientists start with the simple things: food you cook yourself, and seven to nine hours of sleep.
“Sleeping, very important. […] I do notice that when I’m highly stressed, my sleeping, let’s say, hours tend to get shorter. But then […] it reflects on you the day after or after a few days of that. So I try to maintain also my sleeping schedule as tight as possible. So always sleeping at the same time and for more or less the same amount of hours.”
In plain words: Stress makes sleep shorter, and short sleep makes the next days harder. A fixed bedtime and wake-up time protect you, especially in busy weeks.
Simple ways to sleep well
Illustration: a fixed bedtime, screens off.
None of these costs anything. Pick one, make it a habit, then add the next.
Keep regular times
Go to bed and get up at about the same time every day. In the big UK study, the most regular sleepers had the lowest risk.
Bright room light in the evening delayed the body’s own sleep hormone and, in one lab study, cut the time it was released by about 90 minutes. Softer, dimmer lights after dark tell your body it is evening.
A strong dose of caffeine — about two to three cups of coffee — taken six hours before bed still cut sleep by more than an hour, and people didn’t even notice. The sleep doctors who ran the study suggest no caffeine after about 5 p.m.
“Watching the news before you go to bed at night is certainly a good way of ensuring that you get a bad night’s sleep. Don’t do it. It’s not compulsory to know what’s on the news.”
In plain words: What you put into your head in the last hour of the day stays with you in the night. Choose something calm, and let the world wait until morning.
Where the joy is
A new day: sunrise in Australia, after a good night’s sleep.
In the Live Beyond family we have one rule for everything we share: if it brings no joy, nobody keeps doing it. Sleep may be the most joyful longevity habit of all — you do it lying down, in the dark, under a warm blanket. For a whole year Alek and I shared small rooms, often one bed, sometimes the car, and once I fell asleep on the ferry to Krabi. We learned that a good night is not about a perfect bedroom. It is about a calm mind and a day you were happy to live.
“At the end of the day, every night, I have all my practices of what I do at night, what I do in the morning. […] And one of the things when I’m going to sleep is I will meditate on the three things I’m most grateful for from the day. And invariably, it’s not a deal I had or some guy I met. It is some experience with my kids or my family, right? And that ultimately is what is so meaningful to us. It’s the connection between humans.”
In plain words: End your day by remembering what was good. It calms the mind before sleep — and, like Peter, you will probably find it is almost always about the people you love.
“My youngest one, my 10-year-old, she’ll be like, ‘Can you play the 12-minute help me sleep?’ And she’ll put that on, and she’ll breathe with it, and then you’ll see her fall asleep like while we’re like cleaning up around her. So it’s lead by example, but they also have the tools that they can use it whenever they need to. […] You just make it fun.”
In plain words: Children copy what we do. A calm evening ritual — slow breathing, a story, soft light — is something the whole family can share.
“Absolutely. I love sleeping. You can put me somewhere in bed and I will sleep. I’m the best sleeper […] I would say.”
In plain words: One of the busiest people in longevity medicine we know loves her sleep. A good night is not lazy. It is part of the work — and you are allowed to enjoy it.
How much is enough
Illustration: ten minutes earlier to bed.
These amounts are what sleep experts and official guidelines say. We did not invent them. Everybody is a little different — what matters is that you wake up rested.
And in Singapore, Dr Olivia Lesslar turned to Alek with a reminder we both needed.
“We all go through phases of our life, right? Which means that the fact that you, at some point, are gonna be talking to your grandkids, and you have a choice between telling them some really great stories about your adventures, kinda like this travel with your dad, or telling them about how you really optimize sleep. I don’t know. I think I prefer this one. So live your life. Learn to read yourself. Learn to listen to your body.”
In plain words: Sleep well, but don’t turn it into one more thing to worry about. Learn to listen to your body — and spend your energy on the adventures you will tell your grandchildren about.
Who should be careful
Loud snoring or gasping
If someone tells you that you snore loudly, stop breathing or gasp for air in your sleep, or if you are very sleepy during the day, talk to your doctor. These can be signs of sleep apnea, and many people don’t know they have it until someone tells them.
Official health information (US National Heart, Lung, and Blood Institute) [14]
Trouble sleeping for weeks
If you struggle to fall asleep or stay asleep night after night, talk to your doctor rather than trying to fix it alone. Poor sleep can have causes a doctor can find.
We wrote this page from Live Beyond’s own recorded interviews and the published studies listed below, with gratitude to everyone who taught us. Now we’d love to hear from you: what helps you sleep well? Tell us on Instagram, @longevityadvocate. You are part of this family.
Sources
Every number on this page, by the number in square brackets. Quotations come from Live Beyond’s own recorded interviews, cleaned only of “um” and “uh”. Not medical advice. Talk to your doctor before you change anything.
Rasch B, Born J. About sleep’s role in memory. Physiol Rev. 2013;93(2):681-766. doi:10.1152/physrev.00032.2012
Spiegel K, Leproult R, Van Cauter E. Impact of sleep debt on metabolic and endocrine function. Lancet. 1999;354(9188):1435-1439. doi:10.1016/S0140-6736(99)01376-8
Prather AA, Janicki-Deverts D, Hall MH, Cohen S. Behaviorally assessed sleep and susceptibility to the common cold. Sleep. 2015;38(9):1353-1359. doi:10.5665/sleep.4968
Cappuccio FP, D’Elia L, Strazzullo P, Miller MA. Sleep duration and all-cause mortality: a systematic review and meta-analysis of prospective studies. Sleep. 2010;33(5):585-592. doi:10.1093/sleep/33.5.585
Windred DP, Burns AC, Lane JM, et al. Sleep regularity is a stronger predictor of mortality risk than sleep duration: a prospective cohort study. Sleep. 2024;47(1):zsad253. doi:10.1093/sleep/zsad253
Lloyd-Jones DM, Allen NB, Anderson CAM, et al. Life’s Essential 8: updating and enhancing the American Heart Association’s construct of cardiovascular health: a presidential advisory from the American Heart Association. Circulation. 2022;146(5):e18-e43. doi:10.1161/CIR.0000000000001078
Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation’s sleep time duration recommendations: methodology and results summary. Sleep Health. 2015;1(1):40-43. doi:10.1016/j.sleh.2014.12.010
Xie L, Kang H, Xu Q, et al. Sleep drives metabolite clearance from the adult brain. Science. 2013;342(6156):373-377. doi:10.1126/science.1241224
Watson NF, Badr MS, Belenky G, et al. Recommended amount of sleep for a healthy adult: a joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society. Sleep. 2015;38(6):843-844. doi:10.5665/sleep.4716
Sabia S, Fayosse A, Dumurgier J, et al. Association of sleep duration in middle and old age with incidence of dementia. Nat Commun. 2021;12(1):2289. doi:10.1038/s41467-021-22354-2
Gooley JJ, Chamberlain K, Smith KA, et al. Exposure to room light before bedtime suppresses melatonin onset and shortens melatonin duration in humans. J Clin Endocrinol Metab. 2011;96(3):E463-E472. doi:10.1210/jc.2010-2098
Drake C, Roehrs T, Shambroom J, Roth T. Caffeine effects on sleep taken 0, 3, or 6 hours before going to bed. J Clin Sleep Med. 2013;9(11):1195-1200. doi:10.5664/jcsm.3170
Wood AM, Joseph S, Lloyd J, Atkins S. Gratitude influences sleep through the mechanism of pre-sleep cognitions. J Psychosom Res. 2009;66(1):43-48. doi:10.1016/j.jpsychores.2008.09.002
National Heart, Lung, and Blood Institute (NIH). Sleep apnea — symptoms. Updated January 9, 2025. https://www.nhlbi.nih.gov/health/sleep-apnea/symptoms
