Ever wondered how some who people sleep for shorter duration are as fresh as those who sleep for 8-9 hours every day? The secret lies in the genes. A mutation in a gene known as hDEC2 is apparently responsible for a shorter sleep requirement. Only some people have this mutation.
A paper published online in the journal Science found that this mutation allowed two members of an extended family to sleep for just six hours every day, and remain fresh throughout the day. Several studies have shown that humans generally need eight to eight-and-half of sleep over time to maintain good health.
The mutation appears to affect only the duration of sleep and not the sleep timing. It does it by turning off the expression of other genes connected to sleep, including those that control the circadian rhythm — an internal clock that determines a person’s sleep-awake cycle.
The team led by Ying-Hui Fu, Professor of Neurology, University of California at San Francisco, U.S., used genetically engineered mice that carried the mutated gene to ascertain its effect of sleep duration.
Ms. Fu found the mutant mice sleeping one hour less than mice that did not carry the mutation. The same was the case with fruit flies too. Mutant fruit flies slept about two hours less that the control ones that did not carry the mutation.
Next, Ms. Fu will study the exact role of the mutant gene. But it is possible that the mutation to the hDEC2 gene may not be the only cause for shorter duration of sleep. Eight years ago, Ms. Fu and her team found a mutation in a gene (Per2), which caused familial advanced sleep-phase syndrome (FASPS). People with this syndrome go to bed early: about 6 p.m. or 7 p.m. and wake up at 3 a.m. or 4 a.m.
