If you’re a parent (or really just a human yourself) then you know that some people sleep better than others. Parents can see that one child loves to sleep and was always a good sleeper as a baby, while another has to be coaxed to sleep each night. Now, scientists think they can explain why.

According to investigators at the Washington State University, some people are born with a gene that helps them to sleep better at night. Apparently, mice with the FABP7 gene intact slept better than did those mice for whom the gene wasn’t intact.

The researchers then looked at 300 Japanese men who underwent a seven-day sleep study that included looking at their DNA. Of the 300, 29 of the men had a variant of the gene that is responsible for producing FABP7 and they tended to have irregular sleep patterns. They got the same amount of sleep as the other participants, but they woke often during the night.

The researchers also looked at fruit flies and found that those flies with a mutant FABP7 slept less restfully.

As Dr. Gerstner said, “This suggests that there’s some underlying mechanism in astrocytes throughout all these species that regulates consolidated sleep. It’s the first time we’ve really gained insight into a particular cell’s and molecular pathway’s role in complex behavior across such diverse species.”