Most people need seven to eight hours a night, and insufficient sleep is fast becoming a public health epidemic. A previous study looked at a family of short sleepers who only needed six hours a night. A mutation in the DEC2 gene -- also known as BHLHE41 for basic helix-loophelix family member e41 -- was discovered to be the underlying reason for their superhuman power.
Now, a team led by Renata Pellegrino from the Children's Hospital of Philadelphia wanted to see if there were other variants of this gene. They studied 100 twin pairs: 59 were monozygotic (identical twins) and 41 were dizygotic (fraternal twins). All pairs were the same sex and otherwise healthy. The team measured their nightly sleep duration at home for up to eight days using an actigraph unit to measure sleep patterns. In the lab, the team also looked at the twins’ responses to 38 hours of sleep deprivation and the length of recovery sleep they required.
They found one variant of the BHLHE41 gene, called Y362H, in one twin in a fraternal pair that conferred reduced sleep duration. Even after sleep deprivation, he needed less recovery sleep and showed fewer performance lapses than his twin.
This participant slept five hours each night on average -- that’s more than one hour shorter than the non-carrier twin, who slept for about six hours and five minutes each night. The twin with the gene mutation also had 40 percent fewer lapses of cognitive performance on average during the 38 hours without sleep; this was measured every two hours using the Psychomotor Vigilance Test. This twin also required less recovery sleep afterward -- sleeping only eight hours after the period of extended sleep deprivation. His twin brother slept for 9.5 hours.
“This study emphasizes that our need for sleep is a biological requirement, not a personal preference,” Timothy Morgenthaler of the American Academy of Sleep Medicine says in a news release. He was not involved with the study.
No word on whether Benjamin Franklin, Margaret Thatcher, Winston Churchill, or Napoleon carried the gene variant.