Are you a “night owl”- wide awake and active till way past midnight, but somehow still manage to wake up early to get to work? Or are you that person who is early to bed but late to rise, because your body needs at least 10 hours of sleep to function the next day? Well, either way, you may find some clues from your genes.
Scientists have identified 76 new gene variants that are associated with the amount of sleep you get, throwing new light on the mechanisms of the sleep-wake control centers of the brain.
This study conducted by researchers from Massachusetts General Hospital (MGH) and the University of Exeter Medical School is the largest of its kind, including more than 446,000 participants in the U.K. who self-reported the amount of sleep they typically received. As a result, they found that genes are responsible for 10-40% variation in an individual’s sleep duration.
While 7-8 hours of sleep per night is considered optimum, 6 hours or less is considered too little sleep and more than 9 hours, too much.
It is known that too much and too little sleep are harmful and can lead to chronic diseases.
This study also found genetic links associated with poor sleep patterns and conditions like depression, higher levels of body fat and fewer years of schooling!
In order to probe these associations further, scientists conducted separate gene association studies on groups of people who reported lower than average sleep hours and longer sleep duration.
There were some interesting findings-- short sleep duration was genetically associated with traits like insomnia and smoking, while longer sleep duration was associated with schizophrenia, type-2 diabetes, and coronary artery disease.
Not relying on data from questionnaires alone, participants in the study were asked to wear accelerometers (motion-detecting devices like Fitbit) for up to a week before undergoing genetic testing for the 78 sleep-duration associated gene variants.
Investigators were able to objectively associate these genetic regions with not just the number of hours of sleep that the individual got, but also sleep quality, instances of waking up in the night and daytime inactivity.
Interestingly, the gene regions associated with sleep duration were different from those associated with insomnia or sleep chronotype, identified in previous studies.
This study helps in understanding each person’s natural optimal sleep duration for a refreshing sleep.