Experiencing problems like insomnia or hypersomnia could be genetic, say researchers who identified 76 new gene regions associated with the time a person sleeps.
It is well known that regularly getting adequate sleep -- 7 to 8 hours per night -- is important for health, and both insufficient sleep -- 6 or fewer hours -- and excessive sleep -- 9 hours or more -- have been linked to significant health problems.
Family studies have suggested that 10 to 40 per cent of variation in sleep duration may be inherited, and previous genetic studies have associated variants in two gene regions with the sleep duration.
The study from the Massachusetts General Hospital (MGH) in Boston, US, analysed genetic data from more than 446,000 participants, who self-reported the amount of sleep they typically received.
The study identified 78 gene regions -- including the two previously identified -- as associated with sleep duration.
While carrying a single gene variant influenced the average amount of sleep by only a minute, participants carrying the largest number of duration-increasing variants reported an average of 22 more minutes of sleep, compared with those with the fewest.
This was comparable to other well-recognised factors that influenced sleep duration.
“While we spend about a third of our life asleep, we have little knowledge of the specific genes and pathways that regulate the amount of sleep people get,” said Hassan Saeed Dashti from MGH.
“Our study suggests that many of the genes important for sleep in animal models may also influence sleep in humans and opens the door to better understanding of the function and regulation of sleep,” Dashti added.
The study, published in Nature Communications journal, also found shared genetic links between both short and long sleep duration.
It also found factors such as higher levels of body fat, depression symptoms and fewer years of schooling, implying negative effects from both too little and too much sleep.
While short sleep duration was genetically linked with insomnia and smoking, long sleep duration was linked with ailments such as schizophrenia, Type-2 diabetes and coronary artery disease.
