Why is January the most depressing month? Experts say it's because of personal finances and the weather. While December is when people are in a joyful and giving spirit because of the holidays, January is reportedly the time they have to pay for it. The average American racks up an average of $1,300 of debt during the holidays. When those credit card bills are due January, some people may find themselves feeling overwhelmed. January is also prime time for Seasonal Affective Disorder.