Blue Monday is a term that was coined a few years ago to refer to the third Monday in January (which this year happens to be today - 16 January 2012.) It's supposed to be the day of the year when everyone feels worse than on any other. This should be because of the short dark days, long time to wait before the spring, feeling let down by lack of excitement after Christmas and so on. Plus, of course, nobody likes Mondays.

So is it true? Basically, no. That is, it's certainly true that, in the northern hemisphere, by mid-January we're often feeling a bit starved of sunshine, the outdoors looks depressing and you can feel tired of waiting for spring. And there are people who suffer real depression from lack of sunlight. But there isn't one day that's worse than all the others, and most of us can get through the winter quite well if we eat sensibly and get some outdoor exercise.

Blue Monday was invented by a travel company, so it's not hard to see that there is probably a marketing angle there (avoid Blue Monday - fly to a sunny destination!)