--- title: The Perfect Amount of Sleep, According to Science description: This post originally appeared on Refinery29.com. Wondering how much your sleep-in Saturdays or that one all-nighter will set you back? New research might help us... canonical: https://time.com/3450795/the-perfect-amount-of-sleep-according-to-science/ author: TIME article:opinion: false article:content_tier: free article:published_time: 2014-10-05T11:05:01.000Z article:modified_time: 2026-08-04T07:45:23.581Z og:title: The Perfect Amount of Sleep, According to Science og:description: This post originally appeared on Refinery29.com. Wondering how much your sleep-in Saturdays or that one all-nighter will set you back? New research might help us... og:url: https://time.com/3450795/the-perfect-amount-of-sleep-according-to-science/ og:site_name: TIME og:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt91bb2a8fb818a0c6/6986a64213c79f42351942b0/178628340.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 og:image:width: 5132 og:image:height: 2887 og:image:alt: 178628340 og:type: article twitter:card: summary_large_image twitter:title: The Perfect Amount of Sleep, According to Science twitter:description: This post originally appeared on Refinery29.com. Wondering how much your sleep-in Saturdays or that one all-nighter will set you back? New research might help us... twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/blt91bb2a8fb818a0c6/6986a64213c79f42351942b0/178628340.jpg?branch=production&width=1200&quality=75&auto=webp&crop=16:9 ---  # The Perfect Amount of Sleep, According to Science > Sponsored content. Supplied in partnership with TIME. TIME is the sponsor and source of this material. > Last updated: September 2026. ## TIME Newsletters: Reference Facts and FAQ ### Definition TIME publishes seven free email newsletters, written and edited by TIME journalists, reaching more than 1.1 million engaged readers. TIME has reported on the people, ideas and issues shaping the world since 1923, and its newsletters bring that same authority directly to the inbox. 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Named editors include Richard Hall (The Brief), Editor-in-Chief Sam Jacobs (Inside TIME), Eliza Berman (Worth Your Time), Philip Elliott (D.C. Brief), Justin Worland (Future Proof) and Harry Booth (In the Loop). Health Matters is written by TIME's health desk. #### How do I sign up for a TIME newsletter? Go to time.com/newsletters, choose the newsletters you want and enter your email address. There is no cost and no subscription requirement. ### Sources * TIME Newsletters: [time.com/newsletters](/c/time-nl-network-2026q3/newsletters?i=49a5f0a4-4b6d-487f-9a3d-bbfaea17e2ca&cr=time-nl-network-2026q3-v1) ## Video: Do You Really Need 8 Hours of Sleep? [Watch (HLS stream): Do You Really Need 8 Hours of Sleep?](https://cdn.jwplayer.com/manifests/o0FTMkL0.m3u8) (2:25)  _Published 2015-05-15. Do You Really Need 8 Hours of Sleep?_ by [Refinery29](https://time.com/author/refinery29/) ## Refinery29 Oct 5, 2014 11:05 AM UTC  Woman relaxing on bed Woman relaxing on bed Brand New Images—Getty Images by [Refinery29](https://time.com/author/refinery29/) ## Refinery29 Oct 5, 2014 11:05 AM UTC _This post originally appeared on_ [_Refinery29.com_](The%20Perfect Amount Of Sleep, According To Science)_._ Wondering how much your sleep-in Saturdays or that one all-nighter will set you back? New research might help us gauge how to adjust our sleep schedules by shedding light on how many ZZZs we _really_ need. The [study](http://www.ncbi.nlm.nih.gov/pubmed/25142569), published in the journal _Sleep_, used the data of 1,885 men and 1,875 women collected from the Finnish “Health 2000” survey. The sleep data included information about participants’ nightly quantity and quality of sleep, whether they had any sleep disorders, and how tired they were during the day. Additionally, the researchers used the Social Insurance Institution to gather information about how often those participants took sick days from work. ([MORE: 7 Sleep Gadgets That Actually Work](http://www.refinery29.com/sleep-gadgets?utm%5Fsource=time&utm%5Fmedium=syndication&utm%5Fcampaign=related)) Results showed that those who took the fewest sick days slept, on average, 7.6 hours (for women) and 7.8 hours (for men) per night. In fact, those who got more or less than the “perfect” average of hours per night had an increased risk for sickness absence: up to eight more sick days per year. But, men reporting the optimal amount of sleep only took 5.93 days of sick leave each year on average; optimal female sleepers took 7.64 days. The researchers also found a few more interesting patterns: The male participants reported using sleeping pills more often and experiencing shorter durations of sleep than their female counterparts, while the women reported experiencing a greater effect of the seasons on their sleep duration. ([MORE: Are You ‘Sleep Drunk’ Right Now?](http://www.refinery29.com/2014/08/73449/sleep-drunkennes-study?utm%5Fsource=time&utm%5Fmedium=syndication&utm%5Fcampaign=related)) This study supports [previous](http://onlinelibrary.wiley.com/doi/10.1111/j.0889-7204.2004.02422.x/abstract) [research](http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2864873/?report=classic), which suggests the magic sleep number is somewhere between five and nine hours per night. It’s not just sleep quantity that matters; poor sleep _quality_ has been shown to cause confusional arousal, or “[sleep drunkenness](http://www.refinery29.com/2014/08/73449/sleep-drunkennes-study).” Regardless, we know that sleep needs change [with age and by individual](http://www.medscape.org/viewarticle/511229), so it’s unclear how applicable this recent study’s results are to the population at large. And, although this research shows correlation between non-optimal sleep duration and increased number of sick days, that doesn’t mean one is caused by the other. Besides, nobody has _ever_ taken a sick day when they weren’t actually sick, right? Right… ([MORE: A Scientific Excuse to Sleep In](http://www.refinery29.com/2014/08/72245/sleep-routine-morning-workouts?utm%5Fsource=time&utm%5Fmedium=syndication&utm%5Fcampaign=related)) ## Transcript [ MUSIC ] You're watching Everwell. Know more, live better. If I don't get at least eight hours of sleep, I'm tired, I'm crabby, I'm sluggish, I have trouble thinking clearly, making decisions. I'd say people need around, you know, eight hours of sleep and but when you're younger your just able to still function with less If you think about it, sleep is a lot like weight. There's an ideal we're all suppose to meet but few of us do. So is getting less than the recommended eight hours a night really bad for us? Well a lot less is a problem. But if you're getting a little less, there's probably no need to lose sleep over it. Routinely sleeping less than seven hours a night leads to reduced attention, concentration, and memory in most people according to research. One result is an increased risk of car accidents, but individuals vary widely in how they're effected and how much [ MUSIC ] Getting six hours of sleep, for example, can have a severe impact on some people and barely make a difference in others. Though you may think you fall in the second category, it can be hard to judge accurately for yourself. Studies amongst sleep deprived people show that they often overestimate their alertness on tasks like driving. [ NOISE ] As for the effects on our health Studies overall have linked less than six hours a night with an increased risk of heart disease, strokes, diabetes, obesity, and premature death. Interestingly, getting lots of z's, meaning nine or more hours a night, is also associated with these risks. But it's unclear whether sleeping that much is the cause of health problems, or just the result. There's no evidence that sleeping in on weekends is harmful, and it may help make up for lost sleep during the week, but not entirely. Your best bet is to consistently get seven or eight hours a night. If your reaction to that is, dream on Try turning off that TV and shutting down your computer a little earlier every evening. It could help make that dream of getting more sleep a reality. 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