German researchers have found a gene that may cause people to have trouble sleeping. The gene, called ABCC9, seems to affect the amount of hours that each person needs to sleep daily. This study looked at 4,000 people across seven European countries. Participants filled out a survey about their sleeping habits, then the researchers compared the answers to variations in gene patterns among the participants. Those who possessed two of the ABCC9 gene slept significantly fewer hours per night than those who had two of a different type of gene. These findings could also help to explain why some people are okay with only getting a few hours of shut eye while others seem to be complete zombies when they do not get adequate sleep.