Light boxes are standard for SAD and they work if you use it right for you. There used to be an online assessment that would give you an appropriate schedule, but I think they took it down a few years ago. It's based on your circadian rhythm. If your circadian rhythm is delayed (you tend to stay up late at night and have trouble waking up on time), you need bright light in the morning. If you have advanced circadian rhythm (tired in the evening, waking up too early), you need bright light in the afternoon.

Sunlight is as good or better, even on a cloudy day, if you get yourself outside into the sun, even if it is cold, at the right times consistently. Light diluted through a window might not be good enough.

Bipolar disorder can be managed using dark therapy - eight hours of complete dark or only yellow light on a consistent schedule every night.

Exercise also helps. Carb craving can be one symptom of SAD. Food is the number one most abused anti-anxiety drug in America. Exercise is the number one under-utilized anti-depressant.

Treatments that work for other types of depression also help for SAD, and light therapy has also shown benefits for non-seasonal depression.