Do We Really Need Eight Hours of Sleep?

For years, we’ve been told that adults need eight hours of sleep every night. But where did that number come from—and is eight really the magic number?

The “eight hours” idea has roots in the 19th century, when the slogan of eight hours for work, eight for recreation, and eight for sleep became popular. Today, however, researchers are taking a closer look at how humans sleep without modern conveniences such as electric lights, alarm clocks, and late-night screens.

Studies of some contemporary hunter-gatherer communities have found surprisingly short periods of measured nighttime sleep—roughly 5.7 to 7.1 hours in one set of observations. People often woke naturally around dawn and did not necessarily compensate with long daytime naps. This raises an interesting question: perhaps the timing and quality of sleep matter as much as the number of hours.

But there’s an important caveat. These communities cannot simply be treated as a model for modern life. Their environments, daily activities, social pressures, health conditions, and lifestyles are dramatically different from ours. Measuring sleep with wearable devices also isn't the same as measuring every minute a person spends in bed.

The bigger lesson may not be that everyone should start sleeping six hours. Instead, it may be that there is no single perfect number for everyone. Sleep needs vary between individuals, and getting enough restorative sleep is important for health, concentration, mood, and overall well-being.

Perhaps the better question isn't, “Did I get exactly eight hours?” but, “Am I consistently getting enough sleep to feel and function well?”

Eight hours may be a useful guideline—but it isn't a universal law of human biology.

REFERENCE

Pandi-Perumal SR, Saravanan KM, Spence DW, et al. The new science of sleep: Insights from pre-industrial societies and phylogenomics. Brain Medicine. Published online 25 August 2026. doi:10.61373/bm026w.0060 

Dzierzewski JM, Hirshkowitz M, Dautovich ND, et al. How much sleep do you need: A 10-year systematic review of National Sleep Foundation’s sleep duration recommendations and examination of sex differences. Sleep Health. 2026;12(4):599–611. doi:10.1016/j.sleh.2026.05.011.
Recent systematic review that re-certified the NSF recommendations.

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.

Paruthi S, Brooks LJ, D’Ambrosio C, et al. Recommended amount of sleep for pediatric populations: A consensus statement of the American Academy of Sleep Medicine. J Clin Sleep Med. 2016;12(6):785–786. doi:10.5664/jcsm.5866.

Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation’s updated sleep duration recommendations: Final report. Sleep Health. 2015;1(4):233–243. doi:10.1016/j.sleh.2015.10.004.

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. Circulation. 2022;146(5):e18–e43. doi:10.1161/CIR.0000000000001078.

Itani O, Jike M, Watanabe N, Kaneita Y. Short sleep duration and health outcomes: A systematic review, meta-analysis, and meta-regression. Sleep Med. 2017;32:246–256. doi:10.1016/j.sleep.2016.08.006.

Hirshkowitz M, Whiton K, Albert SM, et al. National Sleep Foundation's updated sleep duration recommendations: final report. Sleep Health. 2015;1(4):233–243. doi:10.1016/j.sleh.2015.10.004 
Paruthi S, Brooks LJ, D'Ambrosio C, et al. Recommended amount of sleep for pediatric populations: a consensus statement of the American Academy of Sleep Medicine. J Clin Sleep Med. 2016;12(6):785–786. 

Watson NF, Badr MS, Belenky G, et al. Joint consensus statement of the American Academy of Sleep Medicine and Sleep Research Society on the recommended amount of sleep for a healthy adult. Sleep. 2015;38(6):843–844. —
In a joint consensus statement, the American Academy of Sleep Medicine and Sleep Research Society taskforce recommended ≥7 hours for adults aged 18–60 years.

St-Onge M-P, Aggarwal B, Fernandez-Mendoza J, et al.
Multidimensional sleep health: Definitions and implications for cardiometabolic health: A scientific statement from the American Heart Association. Circ Cardiovasc Qual Outcomes. 2025 May;18(5):e000139. doi:10.1161/HCQ.0000000000000139.

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