The heady cocktail of post-Christmas debt, no money, miserable weather and lack of motivation is enough to give anyone the Monday morning blues.

However, anyone suffering with the malaise need not worry as they are not alone because today is officially Blue Monday, the most miserable day of the year.

Blue Monday marks the start of the final full week in January and is seen as the time when people experience a series of combined depressive effects.

According to renowned stress expert Dr Cliff Arnell, six eternal factors collide to create the problem, including the weather, the festive holiday being over and lack of motivation.

Dr Arnell, a former lecturer at Cardiff University, has even designed a formula on which to base his theory - ([W + (D-d)] x TQ) (M x NA).

W being weather, D - debt, d - money due in January pay, T - time since Christmas, Q - time since failing new year's resolution, M - low motivational levels, and NA - feeling of a need to take action.

Debbie Golec, managing partner of Yorkshire Bank's Birmingham Financial Solutions Centre, said: "Towards the end of January people are getting back to everyday working life after the holiday period, but the sudden realisation that the Christmas bills need paying, New Year resolutions have already been broken and life just isn't panning out the way it was supposed to can hit hard," she said.

She said that employers needed to be on the look out for signs of stress, depression and anxiety.

The Health & Safety Executive recently found that work-related stress costs the UK economy £3.7 billion a year.