For people having a hard time facing the world today, there's now quantifiable reason to believe you're not alone.

According to a British expert in the seasonal ebb and flow of peoples' moods, Jan. 24 is typically "the most depressing day" of the year -- and in 2005 it's even worse because it falls on a Monday.

The University of Cardiff's Dr. Cliff Arnall singled out today based on a complex calculation of six mood-affecting factors.

Arnall starts with the season's combination of shortened days and poor weather (W), and adds the post-Christmas financial burden of debt (D) minus monthly salary (d).

Then, he factors that with a combination of time since Christmas (T), the time since new year's resolutions were abandoned (Q), and divides that by the product of low motivation (M) and the feeling of needing to take action (NA).

In sum, the formula looks like: [W + (D-d)] x TQ M x NA

And when Arnall crunched the numbers, they added up to Britons' worst day of the year.

And the equation would seem to apply to Canada as well, where winter often brings with it a blanket of depression that's been dubbed seasonal affective disorder, or SAD.

More severe than a run-of-the-mill seasonal low, SAD is characterized by often debilitating depression. Short of escaping wintry climes for someplace sunny, sufferers can seek phototherapy -- in which they sit in front of a bright lightbox -- or turn to antidepressant drugs.

Experts says moderate physical activity, however, can be enough to lift people out of a mild case of the winter blahs.