Start with the weather. Add it to the difference between your debt and monthly income. Multiply the figure you get by the number of days since Christmas, to the power of when your New Year’s resolutions broke down. Take that figure and divide it by your level of motivation multiplied by your feeling of a need to take action.

And the answer is? Blue Monday.

There’s clearly not a lot of science in this calculation - it was ‘formulated’ in 2005 by Cliff Arnall, a further education tutor, as a PR stunt and has been used to help promote everything from holidays to bottled water since then. Usually it’s the third Monday of the year (a much easier calculation to work through).

Even without a dubious formula, most of us would agree that mid-January can be the most miserable time of year. Low levels of light and high levels of post-Christmas debt collide mid-month. To cap it all, you’ve discovered that the ‘new you’ is exactly the same as the old one.

For employers the lethargy caused by January’s mid-month motivational slump multiplied by the stress of financial worries can have a genuinely quantifiable effect on productivity. Workers who are finding it hard to make it through to their next payday are unlikely to perform at their best. And for those that were struggling with debt before the festive expenditure surge, January is likely to even harder.

Here are four ways that businesses can help their staff get past the blues and onto brighter times:

Help employees with debt:

According to Deloitte, UK consumers expected to spend around £567 each on Christmas in 2018. Given that the UK average take-home pay is around £1,800 each month, paying for Christmas will eat up nearly a third of a month’s disposable income. However, much of the cost will have been loaded onto credit cards – uswitch estimates that around £8.5bn was piled onto plastic to pay for gifts and entertaining over the festive season. That means there will also be interest rates to factor in – so 2018’s expenditure could be hanging over employees well into 2019. Helping employees consolidate debts into a single, manageable sum each month could help them to manage their loan payments more easily and avoid excessive interest charges.

Offer financial education:

Just after Christmas, the Advertising Standards Authority upheld a complaint against payday loan provider Provident, ruling that a marketing campaign for loans with an APR of 535.5 per cent was irresponsible in its use of photos of children and families at Christmas**. The ASA ruled the advert was likely to play on individuals’ emotions, especially if they were already struggling to afford the cost of Christmas. Financial education at work can help employees to understand that high-cost loans are an expensive way of accessing money that is likely to push them further into debt. It can also help them to access more affordable products to limit the long-term effects of borrowing.

Plan ahead:

Financial wellbeing is about being in control of your finances, rather than simply spending less or saving more, so helping employees to plan ahead for major expenses across the year could help to alleviate the gloom next January. Offering access to workplace savings accounts, such as ISAs and helping staff to develop good financial habits, such as budgeting and saving small, regular amounts, can deliver change that lasts for life (and not just for Christmas!).

Get comfortable with financial wellbeing:

Research from Neyber shows that 43% of HR directors don’t feel equipped to help if an employee approaches them about financial problems. And only 3% of the 10,000 employees in our DNA of Financial Wellbeing 2018 survey said that they would approach their HR department if they had a financial problem. However, the workplace is an ideal place for employees to get help with their finances – or at the very least as a gateway to sources of support, such as Employee Assistance Programmes and affordable loans.

There is a very real reason for doing this:

According to the charity Money and Mental Health, around 100,000 people per year attempt to take their own lives while struggling with problem debt***. Many others may not get to that stage of desperation but will suffer significantly from poor mental health related to their finances.

Building a culture of openness around financial wellbeing at work means combining support for employees’ financial worries with helping staff become better equipped to manage their finances, reduce their borrowing costs and start to build for the future. That could help some employees to simply become better equipped to cope financially next Christmas – but it could also stem much more serious financial and mental health problems that extend far beyond the workplace. Offering that support is a genuinely compelling formula for Blue Monday.