Whether you’re an early bird or more of a night owl, however you manage to sleep is influenced by your genetics, according to researchers from The Rockefeller University in New York.
Researchers found that a gene known as CRY1 can mutate to change one’s natural circadian rhythm. The circadian clock operates in the tissues and cells of organisms in order to syncopate behaviors with 24-hour environmental cycles, the authors wrote.
Individuals who were found to have the CRY1 gene variant reported later sleep times, extended naps during the day and fragmented sleep for those whose schedules required an early wake-up call. Alina Patke, co-author and research associate from The Rockefeller University, said those with the genetic variant have a different quality of life.
“Carriers of the mutation have longer days than the planet gives them, so they are essentially playing catch-up for their entire lives,” Patke said in a press release.
The gene variation was linked to delayed sleep phase disorder (DSPD), a sleep disorder in which a person’s sleeping habits are delayed from the societal norms. The disorder is prevalent with almost ten percent of the general population, according to scientific studies. Those diagnosed with DSPD have a delayed sleep cycle that can even break down into a series of naps instead of significant sleeping periods. Michael Young, co-author and head of the Laboratory of Genetics at The Rockefeller University, said those with DSPD are always a step behind.
“It’s as if these people have perpetual jet lag, moving eastward every day,” said co-author and principal investigator Michael Young. “In the morning, they’re not ready for the next day to arrive.”
The CRY1 gene is a core circadian clock gene that kick starts a release of proteins for the circadian rhythm to function. The genetic variation in the CRY1 gene causes different reactions and a longer circadian rhythm, directly associating the gene with DSPD, the authors said.
The study looked at data from multigenerational families in the U.S. as well as six families from Turkey for a total of 39 Turkish individuals. The participants that carried the CRY1 gene variant had a sleep midpoint of 6 to 8 a.m.
Those who weren’t carriers had sleep midpoints of 4 a.m. Eight of the Turkish individuals inherited the gene from both parents, while the rest inherited the gene from only one parent. One carrier of the study self-reported a sleep routine by enforcing regular sleep and wake times as well as exposing themselves to bright light in the daytime.
Patke said a normal sleeping pattern can be achieved with some effort. “An external cycle and good sleep hygiene can help force a slow-running clock to accommodate a 24-hour day,” she said. “We just have to work harder at it.”
The study was supported by the National Institutes of Health, The Rockefeller University, Weill Cornell Medical College, Calico Life Sciences LLC, the Turkish Academy of Sciences, and the Brain and Behavior Research Foundation.