Still afraid of the dark? It's probably time to get over it. New evidence from Ohio State University found that a dim light at night — whether it comes from a night-light, or staying up late in front of a computer or TV — may be making you depressed. Here's what you should know:

What happened in this study?

University researchers exposed hamsters to a faint light when they went to sleep. Within a few weeks, the animals began to exhibit classic symptoms of depression. The hamsters spurned sugar water (normally, a reliable lure for hamsters) and were more lethargic than peers who slept in complete darkness. They performed poorly on behavior tests. Brain scans revealed changes in the hamsters' hippocampus typically associated with depressed people. "The results we found in hamsters are consistent with what we know about depression in humans," says study author Tracy Bedrosian.

What does artificial light do to the body?

Artificial light disrupts our natural circadian rhythms, which may in turn alter the body's hormone levels. "When people spend too little time in darkness, it seems that the body suppresses release of the hormone melatonin," says Laura Blue at TIME, which is thought to fight a myriad of conditions, including tumor growth and cancers. According to the American Medical Association, interrupting the body's circadian rhythm could also lead to obesity, diabetes, and reproductive problems.

So I should get rid of my night-light?

The team speculates that artificial light may be part of the reason depression rates have soared in recent decades. There is good news, however: When the afflicted hamsters were again allowed to sleep a full eight hours per night in the dark, their depressive symptoms disappeared completely. This offers gloomy night owls some hope, says Bedrosian. "People who stay up late in front of the television and computer may be able to undo some of the harmful effects just by going back to a regular light-dark cycle and minimizing their exposure to artificial light."

Sources: Medical Daily, My Health News Daily, TIME