Gene Mutation Found in ‘Night Owls'

Scientists at The Rockefeller University discovered some people who tend to stay awake for long hours at night have a variant of CRY1 gene causing the slowing down of their biological clock. The result of their study is published in Cell.

"Compared to other mutations that have been linked to sleep disorders in just single families worldwide, this is a fairly impactful genetic change," said Michael W. Young, lead author and head of Rockefeller's Laboratory of Genetics. According to the study, the mutation may occur in as many as one in 75 people in some populations.

The researchers required the subjects to stay in a laboratory apartment for two weeks. They were isolated from all cues to the time of day and were allowed to eat and sleep whenever they needed. Samples of skin cells were also collected from them. Most of the subjects showed a 24-hour sleep-wake cycle. However, those with delayed sleep phase disorder (DSPD) had longer cycles. Changes in body temperature and hormones linked to the biological clock were also delayed. Melatonin, a hormone that helps regulate sleep, usually increase around 9 or 10 in the evening for most people, but those with DSPD get higher levels of melatonin at around 2 or 3 in the morning. The DNA samples of the subjects were also studied and the researchers found that a mutation in CRY1 is common among DSPD patients.

Read Rockefeller's news release and the research article for more details.