Monday, August 4, 2014

Mutant gene that allows people to need less sleep identified, scientists say

A sleep study (AFP Photo / Khaled Desouki) 

US scientists have found a mutation of the little-understood BHLHE41 gene that, they believe, allows a small proportion of the population to get enough rest, without needing to spend a whole night in bed.

University of Pennsylvania scientists deprived 100 pairs of twins – both identical and fraternal – of sleep for 38 hours and tested their alertness every two hours, before checking how much rest they needed to fully recover.

The starkest difference came in a pair of non-identical twins, one with a variation called p.Tyr362His in their BHLHE41 gene, already thought to be important in controlling circadian rhythms. The twin with the mutation regularly slept one hour less than his sibling – needing just 5 hours sleep – made 40 percent fewer mistakes on the test when sleep deprived, and needed 8, and not 9.5 hours to recover after the experiment finished.

The gene did not appear to give its owner a different quality of sleep, but regulated their internal clocks so that they dropped into a beneficial form of sleep – NREM, which is crucial to memorization, cognition and physical recovery – more efficiently than their twin.

“Both twins had almost identical amounts of non rapid eye movement (NREM) sleep,”
concluded the authors, whose research was published in the latest issue of scientific journal Sleep.

“There are a number of mutations of BHLHE41. Mutations reduce total sleep while maintaining NREM sleep and provide resistance to the effects of sleep loss.

Being able to identify – and perhaps later genetically engineer this mutation – could be of vital importance. The most recent National Health Interview Survey shows that almost 30 percent of all Americans have slept for less than 6 hours in the past 24. The majority of these do not possess the helpful mutation, with the deprivation hurting their concentration, speed of thinking, memory and fitness.

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