Anybody who’s ever tried to rouse a sleeping teenager (or who has been a teenager themselves) is probably aware that it can be a tough task. But it’s not without good reason. Research has shown that adolescents require more sleep than adults and children.

Now, a new study drives home just how crucial the amount and quality of sleep is to teens’ brain health.

The sleep patterns of more than 3,000 adolescents were studied, with researchers classifying the teens into three categories. The first included teens who stayed up the latest, had the highest sleeping heart rates and slept the least. The second category featured teens who had a moderate amount of sleep and sleep quality. And the third included teens who went to bed early, had lower sleeping heart rates and slept longest.

The teens with the earliest bedtimes and longest sleep duration consistently displayed better cognitive performance than other participants.

Those who slept least fared the worst in cognitive performance and were shown to have weaker connections between key parts of the brain, and smaller brain volume, in general.

The study showed these results remained consistent as researchers followed the adolescents from ages 9 to 10 through age 14. Researchers said this suggests the sleep patterns established during these years can shape brain function for years to come, so developing and maintaining healthy habits in early adolescence is extremely important.

This research offers clear evidence of how vital sleep is to teens. Perhaps future studies can explore ways to safely wake a sleeping teenager.