Do Some People Just Need Less Sleep?

How much sleep do we actually need? Health professionals recommend at least eight hours of sleep a night, we've heard the advice since the time we were old enough to recognize the meaning of the words. So why is it that some people seem just fine sleeping less? Nearly everyone knows someone that claims they only need four to six hours a night, but are they fooling themselves into accepting their sleep deprived state? Or are these individuals really different in their sleep needs than the average human being?

It is this exact question that spurned sleep researchers to discover what exactly determines how much sleep we need. Even a five year old could tell you that sleep is an essential part of life, but understanding the exact mechanisms surrounding sleep seems to have evaded scientists for ages. We understand the sleep cycle, when we enter into a dream state, and can even track hormones related to the initiating the need for sleep. However, recent research has just shed light into how the body regulates the amount of sleep needed.

An article published in Scientific American discusses research behind "short sleepers," who seem to do well on only six hours of sleep. This amazing breakthrough in sleep study was discovered when researchers looked into a genetic connection between the amount of sleep we need to get by and remain healthy. According to Harmon (2009) a genetic mutation was found on the gene DEC2 that allowed the research subjects (a mother daughter pair, and a group of "transgenic" mice) the ability to "truly need" less sleep. This is especially interesting since a number of reports have warned of the dangers of sleeping less than six hours. One article by Chimes (2011) in the Voice of America cited research that showed health risks, such as an increased risk of heart attack, associated with sleeping less than six hours, and surprisingly with individuals getting significantly over eight hours of sleep as well.

Further research into this area showed that organisms with this genetic mutation saw an increase in 1.2 hours of wakefulness over those without the DEC2 genetic mutation; and when this genetic mutation was removed, the level of wakefulness fell to normal levels (Harmon, 2009).

A recent study published in Science Daily revealed study with cave fish that slept significantly less than their non-cave-dwelling counterparts. Researchers reported that findings pointed to the involvement of genetics in not only sleep patterns, but in sleep disorders as well. Further research in this area is necessary to determine the specifics of the genes involved in this phenomena, as well as track life changes to indicate the lifetime health of these fish, but the finding seems to enhance 2009 studies on the DEC2 gene. However, like the cave fish, those with the DEC2 mutation will also have to be tracked for long-term health effects, both positive and negative, that may be associated with the reduced periods of sleep. Are these individuals also at a higher risk for heart attack and stroke as reported in Chime's 2011 article? Or does this genetic mutation make these individuals so unique that those health risks no longer apply?

Although there is no definite answer to this question, Harmon (2009) explains that people with the DEC2 gene mutation get a more intense REM state sleep, which enhances the effectiveness of sleep without adding on the extra hours. This means that the restfulness is there, and thus it is thought that the health effects placed on individuals without the gene mutation is not there, however, due to the newness of this research, it is hard to say whether that hypothesis will actually prove true.

Furthermore, Harmon (2009) notes that this genetic mutation is really quite rare, "less than one percent of short sleepers" had the gene mutation. This extremely small number seems to indicate that many of self-proclaimed short sleepers do not actually need less sleep, and that they are depriving themselves of necessary sleep and putting themselves at risk for the long-term health effects associated with it. Obviously, the only way to tell whether the gene is present or not is through genetic testing, so perhaps for the time being it's best we all strive for more sleep, and more restful sleep to be on the safe and healthy side.

As with the study on cave fish, the discovery of the DEC2 gene mutation will undergo further research in hopes of better understanding sleep patterns, sleep needs, and sleep disorders. For now, we can only wait for further news on the subject and hope that our understanding of sleep will continue to expand and increase the quality of sleep we get on a nightly basis.

　

References:

Chimes, A. (2011). Sleeping Less Than 6 Hours Might Boost Heart Attack Risk. Voice of America.

Duboue, E.R. (2011). Evolutionary Convergence on Sleep Loss in Cavefish Populations. Current Biology. doi 10.1016/j.cub.2011.03.020.

Harmon, K. (2009). Rare Genetic Mutation Lets Some People Function with Less Sleep. Scientific American.

ScienceDaily. (2011). Cave Fish Insomniacs: Fishes That Sleep Less Point to Genetic Basis for Slumber, Biologists Find. Science Daily.