How Much Sleep Do We Really Need?

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How Much Sleep Do We Really Need

Out of the three pillars of health, sleep seems to be the one most people are willing to negotiate in the name of productivity or entertainment. (1) (And by negotiate, we mean play fast and loose.) But if there’s one thing most sleep experts can agree on, it’s that sleep isn’t negotiable. Time and again, research has shown us just as much — failure to log enough shut-eye has far-reaching consequences ranging from moodiness and irritability to high blood pressure and heart disease. (2) So, how much sleep do we need? Well, that depends. 

Note: The content on Sleepopolis is meant to be informative in nature, but it shouldn’t be taken as medical advice, and it shouldn’t take the place of medical advice and supervision from a trained professional. If you feel you may be suffering from any sleep disorder or medical condition, please see your healthcare provider immediately.

Long Story Short

  • The American Academy of Sleep Medicine recommends that adults get seven or more hours of sleep per night.
  • Your sleep requirements will change throughout your life due to age, general health, and lifestyle factors.
  • Moodiness and irritability, impaired memory, and frequent illness may indicate that you’re not getting enough sleep.

How Much Sleep Do You Need? 

Try as you might, you’d be hard-pressed to find a one-and-done prescription for how much sleep you need. However, if you’re looking for a jumping-off point, the American Academy of Sleep Medicine (AASM) offers the following guidelines for sleep requirements in a 24-hour period by age range. (3)

  • Infants (4 months to 12 months) 12 – 16 hours (including naps)
  • Toddlers (1 to 2 years of age) 11 – 14 hours (including naps)
  • Preschoolers (3 to 5 years of age)  10 – 13 hours (including naps)
  • School Age Kids/Tweens (6 to 12 years of age)  9 – 12 hours
  • Teens (13 to 18 years of age)  8 – 10 hours
  • Adults (18 years and older) 7 or more hours

Again, these are only guidelines, and sleep recommendations vary by institution or organization. The fact is your sleep needs may vary throughout your lifetime based on a host of factors, including your age, lifestyle, and general health. 


Our sleep changes as we age. Variations in sleep requirements tend to change with age due to physical and mental changes and development. For instance, infants need the most sleep because of their profound growth and development in those early years. Adults, however, only need a modest 7 or more hours per night in comparison. (3)


When you’re sick with the flu or common cold, the exhaustion and fatigue accompanying those illnesses are a good sign that you should double down on your rest time. And make no mistake: You may be out for the count, but when you’re snoozing, your body is hard at work fighting your illness courtesy of cytokines (your body’s immune system response to help fight inflammation and infection) that help promote sleep. (4)

But it doesn’t end there — research has also shown that sleeping while sick can offer another assist to your army of cytokines. This one comes courtesy of T cells, a type of white blood cell, that’s part of your immune system. Not only does sleep help T cells easily stick to infected cells and destroy them, but deep sleep (or slow-wave sleep) helps T cells move to lymph nodes, further stimulating an immune response. (5) (6)

Poor Sleep Quality

The quality of sleep you get each night can significantly impact the amount of sleep you need. For example, if your sleep consistently falls short due to a sleep disorder, like obstructive sleep apnea or restless leg syndrome, you may need to make up for lost or poor-quality sleep — often called sleep debt — to feel rested and restored. If you’re wondering just how much catching up you need to do, check out our sleep debt calculator


Sleep problems like insomnia, sleep-disordered breathing (SDB), and restless leg syndrome are quite common during pregnancy. (7) Throw in fluctuating hormones and the physical discomfort of a growing belly, and you can see why sleep really takes a hit in terms of duration and quality among people who are pregnant. These factors can lead to overall sleep loss, fatigue, and daytime sleepiness, ultimately bumping up a person’s need for sleep. (7) (8)


Believe it or not, your genetics may impact how much sleep you need. (9) Not only has research shown that sleep duration and quality may be heritable traits, but your genes can also dictate your chronotype (your preference for staying up late or waking early). (10) Night owls and early birds, you can thank your parents. Genetics also influences your likelihood of developing sleep disorders like insomnia and sleep apnea, both of which can affect the amount and quality of sleep people get. (11) (12)


And finally, your environment plays a crucial role in determining your sleep needs. Those failing to mitigate noise and light disturbances may be more likely to have poor quality sleep, and may eventually require more sleep to make up for their lack of sleep quality night after night. (13)

How Sleep Impacts You 

In a recent podcast by the Harvard Radcliffe Institute, Elizabeth B. Klerman, a neurologist at Mass General Research Institute and a professor of neurology at Harvard Medical School, said, “If sleep does not serve an important purpose, it’s the greatest mistake evolution has ever made.” (14) Klerman goes on to say that we’re not doing things necessary for our survival as a species while we sleep (like hunting or procreating), yet sleep is critical to our health and well-being. And while sleep research is ever evolving (it seems new studies are published almost weekly), a definitive answer to why we sleep remains elusive. 

On the topic, Dr. Robert T. Knight, professor of psychology and neuroscience at the University of California, Berkeley, and Co-Founder of Somnee, tells Sleepopolis, “No one really knows the answer to why we sleep. What we do know is the physiological processes — what’s going on during sleep.” 

Knight says that while we sleep, our body is: (15)

  • Regulating/strengthening the body
  • Maintaining homeostasis (your body’s ability to work correctly by controlling your heart rate, blood sugar levels, etc.). 
  • Eliminating things that are not necessarily important and retaining important information — synaptic pruning and memory consolidation
  • Preparing the brain for the next day of mental action by clearing the “noise” (irrelevant information) from the prior day

Tips for Better Sleep 

While there’s been a lot of chatter — and maybe even some confusion about sleep hygiene and the best practices for improved sleep, Knight says, “There is no “magic” to sleep hygiene — a lot of this is common sense.” 

“Decide how you want to function during the day. The notion that sacrificing sleep to work harder or longer is a fallacy.”

Dr. Robert T. Knight

In addition to minding the time for your sleep cycles, Knight offers the following tips for better sleep. 

  • Be conscious of your bedroom/sleep area setup. Better to sleep in a cool room than a hot one, and be sure to sleep in a dark room with no ambient light.
  • Don’t take any stimulants or drink caffeine (i.e., coffee) within a few hours of bedtime.
  • Don’t bring electronic devices into the bedroom
  • Find a relaxing wind-down activity (i.e., reading a book)

Additionally, Knight says that numbers aside, sleep cycles matter, too. “Most people have between three to five sleep cycles per night, and most will feel more well-rested if they’re able to finish their sleep cycles rather than being woken up in the middle of it,” he says. 

In terms of prioritizing sleep, Knight says, “Decide how you want to function during the day. The notion that sacrificing sleep to work harder or longer is a fallacy.” Fundamentally, he says we have to “Sleep better to perform better the next day. People just need to prioritize what is best for them to be healthy and happy.” 

Knight adds, “A night or two of disrupted sleep is normal. There’s no magic number, but after a week to ten days of disrupted sleep, it may be time to reevaluate your lifestyle.” We’ll add here that prolonged bouts of poor or insufficient sleep may also be a sign of something more serious, and you should probably speak with your doctor. 

How Do I Know If I’m Getting Enough Sleep? 

For those concerned about not logging enough shuteye, Knight says keeping tabs on your sleep is as easy as assessing how you feel. 

The TLDR: “ If you wake up refreshed, you’re getting enough sleep,” he says. 

Other signs and symptoms of insufficient sleep may include: (2)

  • Poor concentration
  • Impaired memory, performance, and productivity
  • Moodiness and irritability
  • Slower reaction times
  • Impaired problem-solving skills

Can I Sleep Too Much? 

Keeping it short and sweet, Knight simply says, “No,” you can’t sleep too much. While everyone requires a different amount of sleep for normal functioning, most healthy people can’t and won’t “overdose” on sleep. And existing research corroborates as much. A 2021 study revealed that oversleeping, or long sleep episodes, are often just temporary as we’re just not programmed to sleep more than is biologically necessary. (16) Incidentally, the same study demonstrated that we have a “homeostatic set-point” for sleep. The research study findings suggest that “the average healthy young human can not chronically sleep over 10 [hours] per day: the average sleep duration was 8.6 [hours]. (16)

Now, just because you can’t technically oversleep doesn’t mean that some people don’t sleep longer than they should. If you find that you are sleeping longer, you may want to keep a sleep diary for a week or two and speak with your doctor. Sleeping longer than usual may be a sign of an underlying health condition, and continually doing so can lead to fatigue and a circadian rhythm that’s thrown out of whack. 


Is sleeping six hours enough?

According to Knight, quantifying “enough sleep” is more a matter of evaluating sleep cycles
“The average number of sleep cycles is three or four,” he says. “Sleep cycles can range from 1.5 hours to 2.25 hours or longer. So, three sleep cycles may average six hours, whereas four sleep cycles on average is eight hours. This is where you get the population average of seven hours.” 

Knight goes on to say, “Total sleep cycle/sleep needs are highly individualized and fluctuate with age/life stage.” The TLDR: aim for around seven hours, but pay attention to your own unique needs, too.

Do women need more sleep than men?

Some research suggests that men are more likely to sleep for shorter amounts of time than women. (17) We’ll also add here that women tend to spend more time in deep sleep, and while they may get better quality sleep than men, research shows that sleep quality and duration often worsen for women with age. (18)

The Last Word From Sleepopolis 

Sleep plays a crucial role in our overall health and wellness. By understanding how much sleep we need, prioritizing quality rest, and practicing good sleep hygiene, we can improve our chances of getting adequate, good-quality sleep night after night. 

Sharon Brandwein

Sharon Brandwein

Sharon Brandwein is a Certified Sleep Science Coach and a freelance writer. She specializes in health and beauty, parenting, and of course, all things sleep. Sharon’s work has also appeared on ABC News, USAToday, and Forbes. When she’s not busy writing, you might find her somewhere curating a wardrobe for her puppy.