Do you have trouble getting a full night’s sleep, but still feel OK in the morning? Perhaps it runs in the family.
A study of 100 pairs of twins has uncovered a gene mutation that might allow for normal functioning on less than six hours of sleep per night. This genetic variant also looks to provide higher resistance to effects of sleep deprivation.
The study found that a participant with p.Tyr362His (a variant of the BHLHE41 gene), had average nightly sleep durations of only five hours. This was more than one hour shorter than the non-carrier twin, who slept for about six hours and five minutes per night.
The twin having the gene mutation also had 40 percent fewer average lapses of performance during 38 hours without sleep and required less recovery sleep afterward. They slept only eight hours after the period of extended sleep deprivation compared with their twin brother, who slept for 9.5 hours.
A Genetic Basis for Short Sleep
The authors say that this is only the second study to link a mutation of the BHLHE41 gene, which is also known as DEC2, to short sleep duration. The study gives new glimpses into the genetic basis of short sleep in humans and the molecular mechanisms involved in setting the duration of sleep that individuals need.
“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. “The mutation was associated with resistance to the neurobehavioral effects of sleep deprivation."
The study group was made up 100 twin pairs, consisting of 59 monozygotic twin pairs and 41 dizygotic pairs, recruited at the University of Pennsylvania. All twin pairs were the same sex and were healthy with no chronic conditions.
Length of nightly sleep was measured at home by actigraphy for seven to eight nights. Response to 38 hours of sleep deprivation and length of recovery sleep were assessed in a sleep lab.
During sleep deprivation, cognitive performance was measured every two hours using the Psychomotor Vigilance Test.
The psychomotor vigilance task (PVT) is a sustained-attention, reaction-timed task that measures the speed with which subjects respond to a visual stimulus. Research indicates increased sleep debt or sleep deficit correlates with deteriorated alertness, slower problem-solving, declined psycho-motor skills, and increased rate of false responding.
The American Academy of Sleep Medicine recommends that adults get about seven to nine hours of nightly sleep, although individual sleep needs may vary. But a small percentage of adults are normal short sleepers who regularly get less than six hours of sleep per night, without any complaints of sleep difficulties and no daytime dysfunction.
“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."
Most people who habitually get six hours of sleep or less, according to the AASM, are restricting their sleep and suffer from insufficient sleep syndrome, which occurs when someone continually does not the amount of sleep needed to maintain normal levels of alertness and wakefulness.
Data from the Centers for Disease Control and Prevention shows that 28 percent of U.S. adults report sleeping six hours or less in a 24-hour period. Insufficient sleep results in increased daytime sleepiness, concentration problems and lowered energy level, and it increases the risk of depression, drowsy driving, and workplace accidents.
Renata Pellegrino, Ibrahim Halil Kavakli, Namni Goel, Christopher J. Cardinale, David F. Dinges, Samuel T. Kuna, Greg Maislin, Hans P.A. Van Dongen, Sergio Tufik, John B. Hogenesch, Hakon Hakonarson, Allan I. Pack. A Novel BHLHE41 Variant is Associated with Short Sleep and Resistance to Sleep Deprivation in Humans. SLEEP, 2014; DOI: 10.5665/sleep.3924