The cause of "Scroogism"?

I often find that Christmas arouses "non-traditional" feelings in me, such as gloom and irritation. Since late adolescence I've found the whole thing a huge chore, and the traditional bonhomie of the time often strikes me as fake. Commercial interests have had their way in getting us all to believe that it starts earlier every year, to the extent that even local authorities now put up street lights in November - several weeks too early in my book. It seems so unfair on the many people for whom Christmas isn't all sweetness and light - I have an aunt and two work colleagues who've all been bereaved in the last few weeks: I'm sure all the exaggerated cheer is going to seem bitterly ironic to them.

Recently it struck me that one reason for my finding Christmas such a pain is probably SAD (Seasonally Affective Disorder). I can't remember ever enjoying winter much, and the excitement of Christmas probably fades for everyone from the age of about ten, but the following certainly rang a bell with me when I read it.

The symptoms of SAD usually recur regularly each winter, starting between September and November and continuing until March or April.

A diagnosis can be made after three or more consecutive winters of symptoms, which may include a number of the following:

Depression

• Low mood, worse than and different from normal sadness
• Negative thoughts and feelings
• Guilt and loss of self-esteem
• Sometimes hopelessness and despair
• Sometimes apathy and inability to feel

Sleep Problems

• The need to sleep more
• A tendency to oversleep
• Difficulty staying awake during the day and/or disturbed sleep with
  very early morning wakening

Lethargy

• Fatigue, often incapacitating, making it very difficult or impossible to carry out normal routines

Cognitive Function

• Difficulty with concentration and memory
• The brain does not work as well, or as quickly

Social Problems

• Irritability
• Finding it harder to be with people

Anxiety

• Tension
• Stress is harder to deal with

Loss of Libido

• Less interest in sex and physical contact

I've believed for some time that I suffer from this, but my slow brain (on account of the effects of SAD?) never really made the connection between this and my vague dread of the Christmas season. Once all the other spending is out of the way, my New Year's Resolution is going to have to be to investigate light boxes. Has anyone reading this found the use of a light box useful against SAD?