How Much Sleep Do We Need?

Multiple factors indicate One’s overall health and wellbeing, and one of these is sleep.  On average, one-third of one’s life is spent sleeping, and the overall sleep quality or sleep health is a matter of importance throughout one’s life. Most of the people are fully aware that they need to sleep properly and for the right amount of time to stay fully active and alert during the day. However, not all can preauthorize sleep as they need to or add it to their routine daily plans as a factor of importance. In the modern lifestyle where a lot of people are hard pressed to work harder, it has become more and more difficult to compensate for the sleep debt. This is the cumulative effect of lost sleep which the body deserves to be compensated for.

Factors Influencing Sleep Duration

The importance of sleep raises the vital question of how long should one sleep to attain optimal health. Interestingly, the duration of sleep required by an individual is shown to exhibit intra-individual as well as inter-individual variations. A degree of heritability has also been shown by studies in terms of sleep durations.  This reveals that there are genetic influences on the need for sleep in terms of the duration of sleep 1. Besides the genetic factors, there are the environmental factors which include the commute time to work, occupational duties, family responsibilities, relationship with friends and colleagues, social and recreational opportunities, career growth, etc. All of these could end up leading to the amount of sleep needed by the individual and the actual sleep; he/she can manage within the given environment 2.

Centers for Disease Control and Prevention (CDC) Study

A study conducted prior to 2015 by the Centers for Disease Control and Prevention (CDC) examined the mean sleep duration of subjects between 1985 and 2012 and noticed that the mean duration for sleep had gone down during this period for American adults and the number of adults who were sleeping for less than 6 hours a day increased during this period.  During this period, this trend meant that the number of adults sleeping for less than 6 hours in 24 hours went up from 38.6 million to 70,1 million in 27 years. These results are startling and show that the modern lifestyle had caused such a massive increase in the number of American adults who were not able to fulfill the proper sleep duration due to various factors that occurred during this period 3.

The CDC takes these results so seriously that it considers this progressive decline in sleep duration as the equivalent of a public health epidemic. The American Academy of Sleep Medicine and Sleep Research Society was able to obtain a 1-year grant in 2013 from the CDC, which was to renew annually for the next five years. The project was known as the ‘National Healthy Sleep Awareness Project’.  This project conducted extensive research on factors related to sleep well as on sleep duration. As for adults above the age of 18, it recommended sleep duration of more than 7 hours. The Sleep medicine and research community have strongly stressed the need for proper sleep to ensure health. However, there is still some confusion about exactly how much sleep is necessary for adults to profess a healthy lifestyle.  There is a lack of consensus on the actual number of hours needed by an adult, which can be considered as the appropriate duration of sleep.  The society is attempting to reach a consensus on the issue so that the society can benefit from the findings, and it can lead to optimal functioning and health in adults 3.

The same study by CDC also noted the self-reported sleep duration had gone down from 1975 to 2004; however, from then on until 2012; it did not register a significant change. The National Institute of Health recommends that a healthy adult need to have at least 7 to 8 hours of sleep in 24 hours while Healthy People 2020 projects envisage a higher sleep duration for adults in the age range of 18 to 21 years, i.e., it envisages more than 8 hours of sleep in 24 hours. For adults aged 22 or above, it envisages more than 7 hours of sleep in 24 hours. Thus, there is a continuous effort from various organizations and projects to ensure that the number of adults who are not having a proper sleep and their sleep duration is less than the one needed by them; their numbers should decrease 4.

World’s Largest Sleep Duration Study

The world’s largest sleep duration study was organized in June 2017, and the total number of participants within a few days of the study had reached 10,000 from around the globe. The Brain and Mind Institute at Western Ontario University released its findings to the Sleep Journal in October 2018.  The study was based on a questionnaire which asked in-depth questions and conducted online scientific investigations. Besides the questionnaire, it had other cognitive performance activities as well. The idea was to gather information about sleep habits on not just one country or region but of the people living throughout the world. The idea of this kind of study was rather new as most other studies had earlier been conducted in small laboratories at specific locations. The questionnaire was quite extensive, and the people who logged in and patriated gave a lot of information to the researchers about what kind of medication they took, their ages, what occupation they pursued as well as hat kind of education they had obtained.  This type of information was considered important by the researchers as the assumption was that some of such factors would have contributed to the nature and duration of sleep they had experienced 5.

Observations in the World Study

Close to 50% of all the partisans in this study reported that they typically slept less than 6.3 hours in every 24 hours. The recommended duration in this study had turned out to be more than 7 hours required for adults. The most interesting observation was regarding those people who had reported that they slept 4 hours or less in 24 hours and these people were noted to be performing as if they were nine years older than what their real age was. The researchers also found out that sleep was affecting all the adults similarly. The amount of sleep which was linked to highly-functional cognitive behaviour, turned out to be the same for all. This was a duration in between 7 to 8 hours. The age of the participants seemed not to matter according to the results. The same was the case with the degeneration of cognitive responses due to sleep deprivation. It did not seem to matter as to what was the age of the individual going through the impairment due to less than required sleep. The researchers found that the optimum duration of sleep, which keeps the brain of a human being performing at its best turned out to be between 7 and 8 hours each night.  This is the same duration as what the doctors normally tell people to sleep in a day so that they can remain fully fit.  It was also noteworthy that the researchers found that people who slept more than this required 7-8-hour duration also faced a similar impairment as the ones who were sleep deprived 5.

Verbal abilities, as well as reasoning, were two main abilities that had been affected the mos by sleep; however, in this study at least, the short-term memory related tasks and activities were not significantly affected.  This appears to be a bit different as compared to what a lot of other scientific studies have found. The results also showed that not sleeping for the proper duration for very long periods would affect the human brain differently as compared to just being forced to stay awake the whole night once. There was some evidence, however, to even suggest that even one night’s absence of sleep could affect the person’s ability to think properly.  Those study partisans who had slept a bit more than usual before participating in this world study performed better than those who had slept less or just the usual amount 5.

Recommendations by the National Sleep Foundation

The expert panel formed at the National Sleep Foundation, which had 18 panelists who are leading scientists and researchers and were given a task by the NSF to recommend the right duration of sleep for different age ranges.  Many leading organizations including American Psychiatric Association, American College of Chest Physicians, American Thoracic Society, Human Anatomy and Physiology Society, Gerontological Society of America, Society for Research in Human Development, American Congress of Obstetrician, American Academy of Paediatrics, etc. had panelists in this expert panel. These experts took part in a rigorous scientific process and reviewed over 300 latest publications and then arrived at a decision after voting on what should the proper duration of sleep be for various age ranges. This included age ranges for the entire lifespan. These recommendations now form the basis of the NSF’s recommendations for sleep duration, which are being followed by millions in the United States and even elsewhere in the world.  For this reason, NSF had to ensure that the recommendations have the backing of a due and rigorous scientific process. Many parents rely heavily on such recommendations 6.

The research could not pinpoint an exact duration for the different age ranges but could put forward ranges of sleep duration to correspondent the different age groups.   Therefore, one needs to ascertain each needs t see what sleep durations seem to keep the person most comfortable and agile. The individual needs to figure out if she/she is happy with 7 hours of sleep or feel better with 8.  The mental and physical health needs to be taken into account as well, and also the amount of caffeine taken per day should be accounted for.  It also is important to ascertain whether one feels sleepy while driving. Once an individual finds the answers to the questions mentioned above, he/she would be able to arrive at a number for sleep duration using the information given by NSF as below: 6

One can notice that as the age increases and the individual exists one age range and enters the next, the sleep requirement decreases. The exception is with the Younger adults and as adults who are required to have 7-9 hours of sleep per day in both the age ranges. The elderly or older adults above 65 years of age are required to sleep a little less as compared to young adults and adults.  Thus, the sleep requirement decreases in the ages from newborn to adults, then remains the same for both young adults and adults. Finally, the sleep requirement decreases as one exits the adult age range and enters the older adult age range.

Less Sleep Required by the Elderly

As shown above, the older adults require less sleep as compared to young adults or adults. A 2008 study at the Women’s Hospital & Harvard Medical School showed that as a result of age-related changes, the older adults would require less sleep. This is, however, true only for those who are healthy and do not take any medication. Similarly, these are individuals who neither have a sleep disorder, not do they have a medical condition. In another study conducted at the University of Surrey in the UK found that the age-related decline in sleep is linked with an even split between the non-REM sleep and the Rapid Eye Movement (REM) sleep, in which a person dreams. Thus, both REM and non-REM are affected equally when the sleep-related changes occur during the old age. Experts say that the lesser need for sleep for the older adults might be convincing some elderly people that they have insomnia, whereas it is quite natural that they would require less sleep. They mistakenly start taking sleep medication, which, in their case, is not necessary 7.

Sleep Requirements for Athletes

Athletic performance seems to be influenced by the amount of sleep an athlete can get. Research at the Stanford Sleep Disorders Clinic and Research Laboratory shows that more sleep leads to better athletic performance, and this is true for all types of athletes. A study published in 2009 had continued to follow Stanford University women’s tennis team for five weeks.  These athletes were trying to get at least 10 hours of sleep every night.  Those who succeeded in doing this ended up increasing their sprint speeds and had been able to hit more accurately as compared to those who had continued to sleep according to their usual sleep timings. The Stanford researches had earlier conducted more studies which had shown that getting extra sleep over an extended period covering many weeks; the athletes had been able to improve their alertness. Mood, as well as performance. This was true for both men’s and women’s swimming teams as well as for the men’s basketball team. The researchers at Stanford convincingly concluded that the sleep factor was a significant one when it came to trying to achieve peak athletic performance on the field 8.

This is extremely important and relevant to professional as well as collegiate athletes as they travel to games and often is on their proper sleep schedule.  The lack of sleep could case sleep debt, which can hamper their performance in the field.  It could also affect their mood, cognitive functions and even reaction time, which is crucial for an athlete incompletion. All of such impairments could easily be tackled by arranging proper sleep time during the athletics and games. Sleeping properly needs to be as important as eating right for an athlete during competition.

Day or Night Sleep

The human body performs better if an individual is awake during the day and sleeps during the night. Going through Jet lag and working night shifts disturbs this and it can even disrupt one-third of one’s genes. A study conducted by British researchers for the Journal Proceedings of the National Academy of Sciences, they subjected 22 healthy individuals to a dimly lit lab environment for three days.  They disrupted their sleep patterns in such a way that on 2nd and 4th day, they slept between 12 noon to 6:30 p.m. On the days when sleep had been shifted, their body clocked dropped to 228 genes. They analyzed that the drop could be as much as one-third of the genes 9. Thus, it is important for people to ensure that sleep during the night and stay awake during the day to have a healthy lifestyle. Those who go through jet lag and night work often have issues with their sleep patterns, and thus, they face impairment of bodily and mental functions.


1Watson NF, B. D. (2010). A twin study of sleep duration and body mass index. J Clin Sleep Med 6, 7-11.

2Basner, M, F. K. (2007). American time use survey: sleep time and its relationship to waking activities. Sleep 30, 1005-95.

3Ford, ES, C. T. (2015). Trends in self-reported sleep duration among US adults from 1985 to 2012. Sleep 38, 829–32.

4Earl S. Ford, T. J. (2015). Trends in Self-Reported Sleep Duration among US Adults from 1985 to 2012. Sleep 38(5), 829–832.

5Owen, C. J. (2018). Dissociable effects of self-reported daily sleep duration on high-level cognitive abilities. Sleep.

6NSF. (2019). How Much Sleep Do We Really Need? Retrieved from National Sleep Foundation:

7SD. (2008, July 25). Older People May Need Less Sleep, Study Finds. Retrieved from Science Daily:

8Quinn, E. (2018, November 11). Do Athletes Need Extra Sleep? Retrieved from Very Well fit:

9Goodman, B. (2014, January 21). Sleep During the Day May Throw Genes Into Disarray. Retrieved from WebMD:

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