Your DNA holds the key if you are a morning person or a night owl. Genetics company 23andMe conducted a DNA analysis on almost 90,000 individuals and found 15 genes associated with being a late or early riser.
The body's internal clock is called the circadian rhythm and it determines the individual's choice between getting out of bed early or staying awake until the wee hours of the night. Scientists call this preference the "chronotype."
Past studies presented genes linked to animal's circadian rhythms. This new study is the first one to analyze the genes' roles in being a morning person or a night owl among humans.
23andMe's David Hinds led a team of researchers to conduct a genome-wide association study where they analyzed various gene variations to determine association with a specific trait. The participants submitted DNA samples and answered two online questionnaires that inquired if they are night owls or morning persons.
Over 135,000 participants answered one survey and 75.5 percent of them were categorized as night or morning persons. This percentage didn't include those who said they had no preference or those who gave conflicting answers in both surveys.
The team found 15 genes attributable to being a morning person and seven of which are located near the genes linked to the circadian rhythms. Several of these genes are also spotted near the ones that help detect light from the eyes. This suggests that the genes found close to each other could share the same goal, which is to tell the person to wake up.
The team also found several patterns. Women (48.4 percent) identified themselves more as a morning person compared to men (39.7 percent). Senior adults over 60 years old (63.1 percent) also preferred mornings compared to adults aged 30 and below (24.2 percent). This pattern supports past findings saying that old adults tend to wake up earlier.
The study participants who identified themselves as night owls are nearly twice more likely to have insomnia. Almost two-thirds of these self-identified night people are likely to have received a diagnosis for sleep apnea. A separate study also suggests that night owls are more prone to developing diabetes.
On the other hand, self-confessed morning folks are less likely to sleep walk or sweat during sleep. They are also less likely to require over eight hours of snooze time.
"We think of our preferences as things that we come up with – things that are kind of spontaneous parts of who we are – but they do have a basis in biology," said study co-author Hinds.
The findings can help improve knowledge about how body clock works among healthy individuals and people with sleep disorders. The findings were published in the Nature Communications journal.
Photo : Oleksii Leonov | Flickr
