Imagine sleeping only four hours a night and waking up refreshed. Although this isn’t the norm for a majority of the population, there are a small group of people where this is a reality.

It is a generally accepted fact that the average person requires about eight hours of sleep every night for their body to function properly. Those who don’t get the recommended eight hours often suffer negative effects such as grogginess, persistent headaches and fatigue. However, there are some people who can go on with only four to six hours a night. Medical professionals are classifying these people as “short sleepers.”

How is this Unusual?

Short sleepers are different from those who knowingly deprive themselves of sleep. In the hectic day-to-day of modern life, most people learn to make due with only six or seven hours of sleep. They power through the negative effects, usually with the help of caffeine. Once the work week is done, they attempt to make up the difference later by taking naps or sleeping in on the weekends. Short sleepers are a little different and seem ideally suited to this modern lifestyle. Short sleepers are unique for being able to operate on only four to six hours of sleep a day without suffering any adverse effects. In fact, they wake up feeling quite refreshed and fully energized.

The study of short sleep falls under the field of chronobiology, also referred to as circadian biology. Chronobiology studies the effects the Earth’s natural cycles of day and night have on the rhythms and cycles present in the human body. As well as sleep, this field also studies the effect time and seasons have on things like mood and pregnancy.

How Does it Work?

Short sleepers naturally sleep only four to six hours, to the point where they do so consistently every night. Similarly, these people do not suffer from insomnia, which affects the quality of sleep and makes it difficult to achieve sleep or stay asleep. Short sleepers enter the kind of deep, restorative sleep that the body needs and they achieve the same effect in four to six hours that normal sleepers do with a full eight.

Research into the source of this trait and the underlying process that cause it are still ongoing. What is known is that this tendency towards shorter sleeping cycles may begin to take effect at a young age. While the exact cause is largely unknown, it is considered to be genetic, a mutation that allows certain people to essentially sleep “more efficiently.”

How Common is it?

It is currently estimated that only 1 percent of the population worldwide are short sleepers. However, the phenomenon has only recently garnered concentrated interest. It may be possible that many people are born with this unique advantage.

Short Sleepers: Sleep Science

The first person to study this phenomenon is genetics professor Ying-Hui Fu of San Francisco, who became aware of it in 1996. A woman suggested they research her family to discover why every member consistently woke up at very early hours. Fu delved into the family’s genetics looking for clues, and then expanded her research to include others who displayed the unusual sleeping habit. She categorized her subjects into three types: early risers, the night owls and a unique third group. Each group shared unique traits. However, this third group stood out as people who consistently slept for short periods no matter what time they went to bed.

How short sleepers are able to function normally with no known adverse effects is still the subject of research. Most people would agree that being able to function optimally on less sleep would benefit their career and personal lives.