Turn the lights off. Or at least that’s what researchers at the University of Colorado Boulder said in a report published in the journal Current Biology.

In a report published by a team of university researchers, people scheduling their day based around the natural schedule of the sun are more likely feel rested and less groggy because their internal clock becomes synchronized with the world around them, balancing their melatonin levels. Researchers say that the disconnect humans have with their outside environment and sleep can make it difficult for people to sleep, and why many experience depression during long, sunless winters.

“We weren’t studying people who had sleep difficulties. The amount of sleep they got did not change. What changed was the timing of their sleep and the timing of their [internal] clock relative to when they slept,” said
Kenneth Wright, an integrative psychologist at the University of Colorado Boulder.

The study examined eight adults, all roughly 30-years-old, and followed them throughout their normal daily functions for one week. The participants of the study spent most of their time indoors with most of their exposure to light being artificial.

Those same subjects were then sent to sleep outdoors. Sleep, light and melatonin were all measured throughout the duration of the study, and at the end of the study, after the participants returned to their regular lives, researchers found that their melatonin levels had changed to make them feel more tired when awoken. However, when the subjects were camping, their melatonin levels synchronized with the sun’s cycle, creating a more natural pattern that allowed them to feel more energized when they woke up, because the levels of melatonin in their body were more balanced.

Though the study was limited, researchers believe that the results that it yielded will inspire similar research. No additional research is scheduled.