Seasonal Affective Disorder (SAD) is a depressive disorder that happens only at a specific time of year (usually winter, though for some people, summer is their low point.) The U.S. National Library of Medicine explains that "some people experience a serious mood change when the seasons change. They may sleep too much, have little energy, and may also feel depressed.
Though symptoms can be severe, they usually clear up."
The Mayo Clinic also lists the following symptoms specifically related to fall and winter disorders:
- Tiredness or low energy.
- Problems getting along with other people.
- Hypersensitivity to rejection.
- Heavy, "leaden" feeling in the arms or legs.
- Appetite changes, especially a craving for foods high in carbohydrates.
- Weight gain.
While the causes for seasonal affective disorder are not entirely known, there is a higher prevalence of SAD diagnoses in more northern climes, indicating that less sunlight is large factor.
Also, if you have had a bout of anxiety or depression in the past, you are at a higher likelihood of developing SAD.
Women seem to be affected more than men, too, for reasons not entirely understood.
It is thought that the lack of sunlight causes a drop in serotonin in the body, which means less of our “feeling good” hormones circulating.
In addition, it is possible that our Circadian rhythms become disturbed by the lack of sunlight, and, like animals, we feel the need to hibernate more.