Misery is expected to peak on Monday, as 24 January has been pinpointed as the worst day of the year.
Staying in bed could be the best option
January has been long regarded as the darkest of months, but a formula from a part-time tutor at Cardiff University shows it gets even worse this Monday.
Foul weather, debt, fading Christmas memories, failed resolutions and a lack of motivation conspire to depress, Cliff Arnalls found.
GPs say exercise and reading up on depression are ways to beat the blues.
"Yes, we do see lots of people with depression and anxiety in the winter months.
"The message is it's not a terrible disorder, people do get better," Royal College of General Practictioners spokesman Dr Alan Cohen said.
JANUARY BLUES DAY FORMULA
1/8W+(D-d) 3/8xTQ MxNA. Where:
d: Money due in January pay
T: Time since Christmas
Q: Time since failed quit attempt
M: General motivational levels
NA: The need to take action
"Exercise and bibliotherapy - reading a number of books to allow people to understand their own symptoms and how to control them," were initial treatments, he said.
The formula for the day of misery reads 1/8W+(D-d) 3/8xTQ MxNA.
Where W is weather, D is debt - minus the money (d) due on January's pay day - and T is the time since Christmas.
Q is the period since the failure to quit a bad habit, M stands for general motivational levels and NA is the need to take action and do something about it.
GPs say exercise will boost spirits
Dr Arnalls calculated the effects of cold, wet and dark January weather after the cosiness of Christmas coupled with extra spending in the sales.
He found 24 January was especially dangerous, coming a whole month after Christmas festivities.
Any energy from the holiday had worn off by the third week of January, he said.
By Monday, most people will have fallen off the wagon or abandoned the nicotine patches as they fail to keep New Year's resolutions.
That compounds a sense of failure and knocks confidence needed to get through January.
The fact that the most depressing day fell on a Monday was not planned but a coincidence, he said.
We would like a photograph that represents how you felt on the day, email them to email@example.com with the subject line 'Misery'.
Do you dread 24 January? Is this the most depressing month? How can you beat the winter blues? The following comments reflect the balance of opinion we received:
We're lucky in Scotland to have Burns' Night on January 25th, which is a great excuse to get together with friends, eat far too much (it doesn't have to be haggis, if you don't like it!) and have a few drinks. I also make a point of taking slightly longer lunch breaks, on sunny days, at this time of year, just to make sure I'm out and about in daylight hours.
Bruce Freshwater, Edinburgh, Scotland, UK
I love winter and really miss the decent fog and snow of East Anglia. Once experienced, who would not miss the keening wind, straight from the Steppes that cuts through you like piano wire? It makes arriving at work seem cosy.
Au contraire, Dr Cohen. I've been looking forward to Monday 24 January since 1 January. I booked a holiday in the sun. Two weeks diving in Tobago. Those mathematical formulae didn't reckon on that, did they?
Jeremy Wright, London
I have four exams which count heavily towards my final degree. The first one? 24 January. Maybe the university will accept these findings as "extenuating circumstances" if I do poorly.
Matthew Loxham, Sheffield, England
I find that the best way to beat the blues is to watch the film The Sound of Music. The heady mixture of drama, action, romance and music lifts the spirits no end.
Ketan B Shah, Harrow, England
I always find August to be the most depressing month, By then, my holiday is over, our national sports stars have all been knocked out of their internationals and Lincoln City begin another futile campaign in the 2nd Division.
Steve Groves, Lincoln, England
It was -30C here yesterday and today we have blizzards. My meagre salary has left me without adequate footwear. My wife is away in England and work is not going so well. However, I am still happy and excited about the new year. Depression only hits you if you let it. Lets have a party and celebrate 24 Jan!
Jack Gilbert, Kingston, Ontario, Canada
In the Shetland Isles, we hold one of the largest fire festivals in Europe - to celebrate our Viking ancestry. So this equation for most here in Shetland, is incorrect. It would be the beginning of February.
Jonny Wiseman, Lerwick, Scotland
If the gloom gets too much and you suffer from Seasonally Affected Disorder as I do, put a small lamp on in the corner of a room to beat those dull overcast days. It really lifts the mood and makes the room feel warmer.
Mark Tingley, London, England
I dread January because I get really cold waiting for the pub to open.
Danny Harrison, Milton Keynes
It's February I dread the most. Christmas is long gone, it's still horribly cold and gloomy and then it happens: Valentine's day. A day of togetherness, happiness and romance... if you're in a relationship, but if not, it's a day of acute reminders of your loveless state.
Dave Andrews, Basingstoke, UK
I couldn't agree with this more - January is the Monday morning of the year - though personally my depression eases on the 16th, once we've passed the half-way point.
Paul Durham, Brandon, Suffolk
It's the day after my birthday which makes it even more depressing, another year older and normally a hangover to boot!
Matt Stephenson, Manchester
Oh for heaven's sake get over it. It's wet, windy, and cold but it's really not that depressing. I have no advice to beat the winter blues because I have none to beat.
This year I decided to make no resolutions and tried to keep my festive spending down. Couple that with missing out on the sales, and it looks like for once I'm ahead of the game!
Dave, Sheffield, South Yorks
Rubbish - I was born on this day and I light up everyone's life. Whoever thought up this formula needs to get out more!!
At work we are all going to be depressed on Monday 24th - probably due to the Ofsted inspection beginning that day!
Louise Gilbert, Cheadle, Staffs
You are lucky to be here and lucky to be alive. Stop whining about being depressed and enjoy the life you've got. Wake up to this amazingly wonderful world that you only get to take part in for one lifetime.
Paul, Dawlish, Devon, England
It's my birthday and my wedding anniversary, so nothing could possibly make it a bad day.
Becca, Oxford, UK
Depression? Who needs it? I've started a life-changing diet and exercise regime and I intend to see it through to the end. I'm in my second week and I feel better already. So, come on the 24th, do your worst!
Chris Combe, Thirsk, North Yorkshire
Beat the winter blues by going out for a run first thing - you'll feel great all morning, and have the 'sleep of the just' at night.
Benedict Faria, London, UK
Next Monday, 24th January 2005, is my 40th birthday. Thanks guys.
Edwin Harrell, Ipswich UK
Move to NZ... it's summer!
Oliver, Auckland, NZ
The 24th of January will be a good day for me - it is pay day!
Tony Ryan, Kingston-upon-Hull
The whole of January is very depressing. Going to work and coming home in the dark, no money, dreadful cold and wet weather - it's enough to send anyone into depression. I find a few gin and tonics help!!
Sarah Elliott, Leicester, UK
Erm, excuse me, but not only is the 24th January my birthday, but it is also pay day. Makes it a pretty good day to me! How wrong the Welsh can be!!
Daniella, London, UK
I hate January more than any other month. It's cold and miserable and we hardly get any light.
John Butler, London
At least the 24th of January is a month after the winter solstice. I can understand the equation, but for someone who likes sunlight, surly we have been on the upslope for a month?
This is the biggest waste of mathematics I have ever had the misfortune to read, and is an embarrassment to anyone who is a member of a British university.
Adam Thorn, Cambridge, England
My office must know about this. Half of them are skiving/on away days/in training that day. Those left behind will struggle through, no doubt.
James, Edinburgh, Scotland
I can't wait until Monday 24th as I will be flying off to sunny Spain for a holiday. Bring it on, I say!
Kate, Reading, UK
Everyone has finished their university exams and the student loans have just come in, January is great!
David Rooney, Belfast , Northern Ireland