Sleep is an essential element of life, with our downtime hours helping us to refresh, energise, and function more effectively during the day. While most of us need seven or eight solid hours of sleep every night just to feel normal, some people manage to get by on much less. Anyone who sleeps for less than five hours a night on a regular basis is known as a short sleeper, with these people awake for up to 60 days more than the rest of us each year. Between 1 and 3 percent of the population are natural short sleepers, with the tendency for less sleep seeming to come from a genetic mutation.
While the exact reasons we need to sleep are largely a mystery, scientists have come up with a number of interesting theories. The inactivity theory is one of the oldest, with sleep said to be a survival function that keeps us safe during the dangerous dark hours. The energy conservation theory offers a different explanation, suggesting that the primary function of sleep is to reduce energy demand. A number of restorative theories have also been suggested, with sleep providing an opportunity for the body to repair and rejuvenate itself. The brain plasticity theory is one of the newer explanations, suggesting that sleep influences the structure and organisation of the brain.
Whatever the exact reasons for sleep, there seems to be a lot of flexibility in how we approach it. According to an international report by the Organisation for Economic Co-operation and Development (OECD) from 2011, people in China get the most sleep with more than nine hours on average. Japan are at the other end of the scale with seven hours and 14 minutes, with Australia a little more than average at eight hours and 31 minutes. It's important to note, however, that some of the data from this study comes from 2006, with people seeming to sleep less all the time.
There are also a lot of differences regarding individual sleeping patterns, with some people able to get by on much less sleep than others. While millions of people around the world are either sleep deprived or suffer from insomnia, short sleepers feel alert and refreshed after waking up, meaning their downtime is more efficient than the rest of us. Genetics may be responsible for differences between people, with Ying-Hui Fu from the University of California recently discovering a tiny mutation in a gene called DEC2.
After studying hundreds of people over the years, Fu found a genetic anomaly between a mother and daughter in the same extended family. “Clearly people with the DEC2 mutation can do the same cleaning up process in a shorter period of time - they are just more efficient than the rest of us at sleeping... But how are they doing that? That’s the key question.” said Fu. “Anecdotally,” she says, “they are all very energetic, very optimistic. It’s very common for them to feel like they want to cram as much into life as they can, but we’re not sure how or whether this is related to their mutations.”
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