Best Sleep Duration for Health

Almost all species on earth need sleep to function optimally, and we humans are no exception. But, how much sleep do we really need to function best? This question has been the subject of considerable debate over a few decades now. Some research even suggests nighttime sleep in humans used to happen in 2 chunks, that is, people used to sleep for 4 hours, wake up for a couple of hours to do active or passive activities, and then return to sleep for another 4 hours. This pattern of sleep, however, began to change in the 17th century—Stephanie Hegarty nicely describes this in this BBC report.

Why is it that in our current society sleeping anything more than 5 hours per night is considered a luxury? Long work hours in jobs requiring little or no physical strain, higher computer/television/smartphone use, lower physical activity levels, stress of related to work and family responsibilities, as well as an active social life are partly to blame.1–3 Poor diet is another obvious factor, but genetics is not.

So for adults at least, the American Academy of Sleep Medicine and Sleep Research Society recently developed a recommendation of at least 7 hours of sleep per night on a regular basis for optimal health.4 Also recently, the National Sleep Foundation lowered its recommendations for adults to include 6 hours of sleep as ‘may be appropriate’. This is clear evidence that the sleep experts cannot agree still; and, it sends mixed messages to the public.

A positive note is, however, the US Center for Disease Control and Prevention now recognizes short sleep as a public health epidemic,5 Therefore, more public health promotion activities to improve sleep duration are likely. In fact, one of the goals of the National Healthy Sleep Awareness Project is to increase the number of adults getting sufficient sleep by 20204 because sleep duration in adults has been decreasing. A typical adult in the US slept about 2 hours more in the 1960’s than in 2002.6 Compared to the 1980’s, twice as many adults are sleeping 6 hours or less per night7 (that is, one in 3 adults are sleeping 6 hours or less per night8). This is really concerning because we know that inadequate sleep, i.e., sleeping less than 7 hours per night on a regular basis,4 is compromises our physical, emotional, and cognitive well-being.9-11


  1. Bixler E. Sleep and society: An epidemiological perspective. Sleep Med. 2009;10, Supplement 1:S3-S6. doi:10.1016/j.sleep.2009.07.005.
  2. Wittmann M, Dinich J, Merrow M, Roenneberg T. Social Jetlag: Misalignment of Biological and Social Time. Chronobiol Int. 2006;23(1-2):497-509. doi:10.1080/07420520500545979.
  3. Berkman LF, Liu SY, Hammer L, et al. Work-family conflict, cardiometabolic risk, and sleep duration in nursing employees. J Occup Health Psychol. 2015;20(4):420-433. doi:10.1037/a0039143.
  4. 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.
  5. CDC Data & Statistics Feature: Insufficient Sleep Is a Public Health Epidemic. Accessed June 5, 2013.
  6. Van Cauter E, Spiegel K, Tasali E, Leproult R. Metabolic consequences of sleep and sleep loss. Sleep Med. 2008;9:S23-S28. doi:10.1016/S1389-9457(08)70013-3.
  7. Ford ES, Cunningham TJ, Croft JB. Trends in Self-Reported Sleep Duration among US Adults from 1985 to 2012. Sleep. 2014;38(5):829-832.
  8. Schoenborn CA, Adams PF. Sleep Duration as a Correlate of Smoking, Alcohol Use, Leisure-Time Physical Inactivity, and Obesity Among Adults: United States, 2004-2006. Sleep. 2008.
  9. Yoo H, Franke WD. Sleep habits, mental health, and the metabolic syndrome in law enforcement officers. J Occup Environ Med Am Coll Occup Environ Med. 2013;55(1):99-103. doi:10.1097/JOM.0b013e31826e294c.
  10. Arora T, Jiang CQ, Thomas GN, et al. Self-reported long total sleep duration is associated with metabolic syndrome: the Guangzhou Biobank Cohort Study. Diabetes Care. 2011;34(10):2317-2319. doi:10.2337/dc11-0647.
  11. Ju S-Y, Choi W-S. Sleep duration and metabolic syndrome in adult populations: a meta-analysis of observational studies. Nutr Diabetes. 2013;3(5):e65. doi:10.1038/nutd.2013.8.
Category Sleep and Health, History of Sleep, Obesity and Sleep

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