is it SAD.

You ought to find a doctor who is familiar with SAD to help you decide if that's what's affecting you.

I would say it's a plausible conclusion. You can try a light-box and see if it helps your symptoms. There's no harm. I understand that some companies give you a trial period and if it doesn't work for you, you can return it. Make sure you will be fully reimbursed if you return it (no restock fees).

If you can imagine yourself doing some exercise, that can trigger your body to release endorphins which can help lift your mood naturally. Sometimes all I want to do is sleep all day, so exercise isn't part of the picture but I thought I'd suggest it just in case.

You ought to have the support of a doctor who can help. I can say from personal experience that it takes some of the burden off.

I've been reluctant to go on antidepressants, but I also have fibromyalgia (which is oddly similar to SAD)and Trazadone and Flexeril help me get deep sleep. I'm on a very low dose, but we may increase it for wintertime as I'm tolerating the medications very well. I'd like to avoid anti-depressants, but I've also been to the point that I was nearly suicidal and I'm not willing to let myself go that low again without help -- even if it be pharmacological intervention.

On the other hand, now that I'm getting help with sleep troubles and pain from fibromyalgia, there's a possibility that this winter will be easier on me.

You also may want to be evaluated for a sleep disorder. Sleep disorders can CAUSE depression. You'll want to just have that ruled out, perhaps. I have a suspicion (and it's entirely my own) that even SAD suffers may benefit from at least being evaluated by a sleep clinic to find out how efficient their sleep is.