According to Mayo clinic the most common symptoms of SAD are irritability, tiredness and low energy, hypersensitivity to rejection, oversleeping, appetite changes and weight gain.
My remedies – try to do the same activities you are normally doing during spring or summer: go out, take long walks, exercise, enjoy the company of your friends, etc.
Also yoga, meditation and massages can really make a difference. Or you can always take a trip to a sunny place to recharge your batteries.
If the symptoms persist, go see a specialist.