The onset of fall brings beautiful foliage, crisp days warmed by hot cider, and holidays celebrating the great pumpkin. Unfortunately, this season’s arrival also means shorter days and therefore fewer daylight hours, which can make everyone a little SAD.

SAD, or seasonal affective disorder, is characterized by feelings of depression or lethargy as a result of infrequent access to light. Symptoms include sadness, weight gain, an inability to focus, constant fatigue, and feeling “under the weather” without a direct cause. Though there isn’t a specific reason for why SAD strikes certain people as the seasons turn darker, there are a few possible instigators. For example, melatonin production rates (a hormone that makes us sleepy) tend to rise in the winter. Serotonin, a mood-elevating hormone, is connected to sunlight—with less sunlight comes a decrease in serotonin, which might cause drops in mood.