A recent study unveils the likely cause behind seasonal depression, a condition that affects 1 in 5 people. Light-sensing cells in the retina that affect whether you feel happy or sad connect with your brain. When the retina cells detect shorter days, the cells send signals to the brain that can result in feelings of sadness or depression. In the study, mice with the light-sensing retina cells experienced depression in the presence of a shortened light cycle; when the cells were removed, the mice didn’t become depressed. Scientists who conducted the study say that their findings help to answer the decade long question about how light is linked to mood. Cell

→Takeaway: If you suffer from seasonal depression, get outside during the day! Exposure to light can do wonders for your mood. Bundle up and go for a mid-afternoon walk or eat a meal outside.