I had terrible trouble during the winter months, and splashed out on a SAD lamp while still being a little cynical about the effect it might have. I tested fortnights on, fortnights off as a personal trial, and I was very impressed. It doesn't resolve all my issues at that time of year, and the British weather is miserable however you look at it, but it helped boost my energy levels so I could at least function from day to day. When I stop using the lamp, I slump into semi-coma again. It takes hours to force myself out of bed. I was convinced! If only I could move to the Mediterranean...