How Much Sleep Do I Need?

Medically approved by
Dr Earim Chaudry
Last updated
7th January 2022

In 30 seconds

Ask “How much sleep do I need?” and you’ll get the familiar recommendation of eight hours a night – but there’s a reason this statistic has stuck. Most likely, it applies to you.

There are exceptions – but they’re not what you think. Some people need less sleep, but many ought to be getting more.

If you’re playing fast and loose with your sleep, you’re risking your health. Check if you’re sleep deprived and prioritise better sleep.

Factoring how much sleep you need isn’t a simple process: your body’s sleep requirements are subject to change, and when you take into account the quality of sleep you’re getting, you enter increasingly complex territory. That’s why most sources will simplify the answer to “how much sleep do I need?” to the catch-all recommendation of eight hours per night. 

But where does that figure come from, and can we get more specific? Here’s what you need to know.

Why Do I Need Sleep?

Before we dig into experts’ recommendations as to how much sleep is enough, it’s helpful to know what “enough” sleep looks like – and why you need it. 

On an anecdotal level, we know the effects of good sleep: it’s associated with more energy and physical performance, increased alertness and better moods. This is supported by scientific findings that good sleep boosts your immunity and mental wellbeing, increases your sex drive and fertility, can help you stay slimmer and helps prevent heart disease and type 2 diabetes.

Beyond this, sleep is somewhat of a mystery. Energy conservation theory posits that we need sleep to save energy, as our metabolic rate drops while we sleep. Brain plasticity theory suggests that sleep enables neural reorganisation, and restorative theory states that sleep allows the body to repair and regrow cells, based on the fact that muscle repair, tissue growth and the release of important hormones occur primarily during sleep. 

Sleep’s mysterious nature means we can only measure “good sleep” from its associated benefits, and “poor sleep” from associated negatives. “Enough sleep”, measured in duration rather than effects, is harder to quantify. This is why it’s important to consider how you feel, too.

What Are the Guidelines?

Let’s build out that “eight hours” statistic. Even without considerations like sleep debt or genetics, the amount of sleep you need varies throughout your lifespan. 

The National Sleep Foundation took two years to collate and evaluate scientific literature on how many hours to sleep and found the following recommendations:

  • Newborns (0-3 months): 14-17 hours each day 
  • Infants (4-11 months): 12-15 hours 
  • Toddlers (1-2 years): 11-14 hours 
  • Preschoolers (3-5 years): 10-13 hours
  • School age children (6-13 years): 9-11 hours
  • Teenagers (14-17 years): 8-10 hours 
  • Adults (18-64): 7-9 hours
  • Older adults (65+): Sleep range is 7-8 hours 

These are guidelines for healthy individuals without sleep disorders. The National Sleep Foundation found that sleep recommendations outside of this range are rare – and they note that habitually sleeping beyond the range can compromise your health, or may be symptoms of health problems.

Can I Get By On 4 Hours’ Sleep?

If the aforementioned two-year analysis won’t convince you to get the recommended hours of sleep, it’s time to address those pervasive stories about CEOs getting by on four. Are some people more efficient at sleeping? 

Genetics could play a part. Researchers discovered that a tiny fraction of the population carry a genetic mutation that enables them to function well after only six hours of sleep. These natural short-sleepers tend to be more optimistic and energetic. This has to do with the circadian rhythm, which is your body’s innate biological clock that influences your sleep-wake cycle in response to light

During the day, your body releases cortisol and adrenaline to make you alert, and at night it releases melatonin to make you sleepy. Natural short sleepers have altered circadian timing, meaning their body responds to the same cues, but performs its responses over a shorter duration.

It’s true: Apple CEO Tim Cook, Virgin CEO Richard Branson and U.S. President Donald Trump have all said they sleep three to five hours a night. It’s certainly possible they have this genetic mutation – but even this group needs six hours’ sleep. More pertinent is the psychology of this brag. Researchers found Americans often sleep more than they report, forgetting to include naps

The tendency for high-powered executives to downplay sleep is troubling. It implies that success comes at the expense of healthy bodily functions, and it equates reduced sleep with increased productivity, when in fact, research shows the opposite is true

Do I Need More Sleep?

You may, in fact, need more sleep – because you need to catch up. Key factors in poor sleep quality or sleep debt include disrupted schedules, stress, illness, or sleep disorders like insomnia. What’s more, you may be sleep deprived without knowing it. Check these tell-tale signs you need to catch more Zs.

  1. Do you fall asleep within five minutes of going to bed? In an ideal world, it should take 10 to 15 minutes to wind down and fall asleep. If you’re out like a light, you’re already too tired.
  2. Do you feel sluggish in the afternoon? Get sleepy in meetings? Nod off in front of the TV? If you’re craving naps,  you’re not getting sufficient sleep.
  3. Do you need an alarm to wake up? It sounds innocuous, but your circadian rhythm should be waking you up. Alarms are a useful precaution and support, but you shouldn’t struggle to wake without one.
  4. Do you sleep in on the weekend? That’s also a sign your circadian rhythm is out of sync and your body is trying to catch up.

If this sounds familiar, try sleeping longer. If you’re already sleeping for the recommended duration, take steps to improve sleep quality. Factors like diet, exercise and your bedroom setting could be important.

The Bottom Line

Eight hours is a useful guide to get enough sleep, but check the National Sleep Foundation’s recommendations and take into consideration how you feel. You can only measure sleep by its effects, and you might not realise you’re getting poor sleep. 

Also, Short Sleep Isn’t Sexy. It’s highly unlikely you’re genetically programmed for less sleep – and impossible to stay healthy on four. If you want to be more productive, get enough sleep. Sleep more efficiently by making sure the hours you get are good ones: improve your Z’s with these tips and consider your body’s natural sleep prompts, like melatonin.   


  1. Luciana Besedovsky, Tanja Lange and Jan Born (2012). Sleep and immune function:

  2. Alexander J Scott, Thomas L Webb and Georgina Rowse (2017). Does improving sleep lead to better mental health? A protocol for a meta-analytic review of randomised controlled trials:

  3. Lee Smith, Igor Grabovac, Nicola Veronese, Pinar Soysal, Ahmet Turan Isik, Brendon Stubbs, Lin Yang and Sarah E. Jackson (2019). Sleep Quality, Duration, and Associated Sexual Function at Older Age: Findings from the English Longitudinal Study of Ageing:

  4. Mei-Mei Liu, Li Liu, Liang Chen, Xiao-Jing Yin, Hui Liu, Yan-Hua Zhang, Pei-Ling Li, Shan Wang, Xiao-Xiao Li and Cai-Hong Yu (2017). Sleep Deprivation and Late Bedtime Impair Sperm Health Through Increasing Antisperm Antibody Production: A Prospective Study of 981 Healthy Men:

  5. NHS – Sleep ‘affects weight loss’:

  6. Michiaki Nagai, Satoshi Hoshide, and Kazuomi Kario (2010). Sleep Duration as a Risk Factor for Cardiovascular Disease- a Review of the Recent Literature:

  7. Deepak Khandelwal, Deep Dutta, Sachin Chittawar and Sanjay Kalra (2017). Sleep Disorders in Type 2 Diabetes:

  8. Janet A. Best, Ian M. Hamilton, Theodore W. Swang and Markus H. Schmidt State-dependent metabolic partitioning and energy conservation: A theoretical framework for understanding the function of sleep:

  9. Max Hirshkowitz, PhD Kaitlyn Whiton, MHS Steven M. Albert, PhD Cathy Alessi, MD Oliviero Bruni, MD Lydia DonCarlos, PhD Nancy Hazen, PhD John Herman, PhD Eliot S. Katz, MD Leila Kheirandish-Gozal, MD, MSc David N. Neubauer, MD Anne E. O’Donnell, MD Maurice Ohayon, MD, DSc, PhD John Peever, PhD Robert Rawding, PhD Ramesh C. Sachdeva, MD, PhD, JD Belinda Setters, MD Michael V. Vitiello, PhD J. Catesby Ware, PhD Paula J. Adams Hillard (2015). National Sleep Foundation’s sleep time duration recommendations: methodology and results summary:

  10. Guangsen Shi, David Wu, Louis J. Ptáček and Ying-Hui Fu (2017). Human genetics and sleep behavior:

  11. Jason Alvarez (2019). After 10-Year Search, Scientists Find Second ‘Short Sleep’ Gene:

  12. Jeanne F. Duffy, M.B.A., Ph.D. and Charles A. Czeisler, Ph.D., M.D. Effect of Light on Human Circadian Physiology:

  13. Guangsen Shi, David Wu, Louis J. Ptáček and Ying-Hui Fu (2017). Human genetics and sleep behavior:

  14. Inc. – Exactly How Much Sleep Mark Zuckerberg, Jack Dorsey, and Other Successful Business Leaders Get:

  15. D F DingesM T OrneW G WhitehouseE C Orne (1987). Temporal placement of a nap for alertness: contributions of circadian phase and prior wakefulness:

  16. Rosekind, Mark R. PhD; Gregory, Kevin B. BS; Mallis, Melissa M. PhD; Brandt, Summer L. MA; Seal, Brian PhD; Lerner, Debra PhD (2010). The Cost of Poor Sleep: Workplace Productivity Loss and Associated Costs:


  18. Siobhan Banks, Ph.D. and David F. Dinges, Ph.D. (2007). Behavioral and Physiological Consequences of Sleep Restriction:

While we've ensured that everything you read on the Health Centre is medically reviewed and approved, information presented here is not intended to be a substitute for professional medical advice, diagnosis, or treatment. It should never be relied upon for specific medical advice. If you have any questions or concerns, please talk to your doctor.

Further reading

From our health centre. Experts, information and hot topics. See all Sleep articles

Sleep by Manual

Get better sleep with Manual

Clinically proven treatments and expert guidance for better sleep, delivered to your door.

Shop Sleep