Researchers pinpointed a gene mutation linked to shorter sleep durations by studying twins.

The research team looked at 100 pairs of twins and identified a gene mutation that allows the carriers to function normally under less than six hours of sleep, the American Academy of Sleep Medicine reported. The findings were published in the Aug. 1 issue of the journal Sleep.

"This work provides an important second gene variant associated with sleep deprivation and for the first time shows the role of BHLHE41 in resistance to sleep deprivation in humans," said lead author Renata Pellegrino, PhD, senior research associate in the Center for Applied Genomics at The Children's Hospital of Philadelphia. "The mutation was associated with resistance to the neurobehavioral effects of sleep deprivation."

The team found those with the p.Tyr362His of the BHLHE41 gene had an average nightly sleep duration of only five hours, which was at least an hour shorter than their non-carrier twin. The twin with the gene mutation had 40 percent fewer average lapses of performance during 38 hours without sleep and needed less recovery time than their twin.

"This work provides an important second gene variant associated with sleep deprivation and for the first time shows the role of BHLHE41 in resistance to sleep deprivation in humans," said lead author Renata Pellegrino, PhD, senior research associate in the Center for Applied Genomics at The Children's Hospital of Philadelphia. "The mutation was associated with resistance to the neurobehavioral effects of sleep deprivation."

To make their findings the researchers measured the sleep of 100 twin pairs using actigraphy. The participants' sleep was screened over the course of seven or eight nights. They were also subjected to a 38 hour sleep deprivation test in a lab.

"This study emphasizes that our need for sleep is a biological requirement, not a personal preference," said American Academy of Sleep Medicine President Dr. Timothy Morgenthaler. "Most adults appear to need at least seven hours of quality sleep each night for optimal health, productivity and daytime alertness."