German scientists discovered a gene that may explain why some people can get by with as little as four hours sleep a night, while others need much longer.
More than 4,000 people from seven European countries took part in the project, which involved filling out a questionnaire on their sleeping habits.
Scientists from the Ludwig Maximilians University Munich then analyzed their answers, along with their genes.
They found that those people with two copies of one common variant of the gene ABCC9 slept for a significantly shorter period than those with two copies of the other version.
After finding that a similar gene was present in fruit flies, the team—in collaboration with scientists from Leicester University, in central England—managed to modify the function of the gene in the insect, which shortened the length of time it slept.
"It is very encouraging for us that ABCC9 also affects the nocturnal sleep period in flies," according to Till Roenneberg, one of the study authors. "This tells us that the genetic control of sleep duration may well be based on similar mechanisms in a wide range of highly diverse species."