Colder weather, shorter days, and women packing their bikinis away until next year can all contribute to the winter blues. However, for some, mental and physical changes brought on by the colder months can point to something more significant.
According to the American Academy of Family Physicians, as many as 25% of people suffer from seasonal affective disorder (SAD) to varying degrees.
Technically a type of depression brought on by decreased exposure to light, SAD comes with a long and diverse list of symptoms, including fatigue, weight gain, oversleeping, decreased motivation to socialize, and comfort-food cravings. If you find yourself not enjoying things you normally would, that's a common sign, too.
The exact physiology of SAD is still being studied. Some researchers think it stems from the mutation of a gene in the retina, melanopsin, that leads to an imbalance in the brain's pineal gland, causing it to increase secretion of the sleep hormone melatonin. While research is ongoing, there are a number of proven ways to effectively manage SAD.