AT the end of a week featuring a day dubbed ‘Black Monday’, there’s a good chance that you’re now much more aware of the effect that shorter days and darker nights can have upon your energy and motivational levels.

It’s the time of year when three or four months of driving to and from work in the dark really begins to test your desire to keep fit and stay active.

‘Black Monday’ refers to the time of the year where they say that you’re most likely to be affected by a lack of vitamin D, or in other words, sunlight.

Sunlight is the most common and easiest way of getting this vitamin, essentially this is one of the feel-good chemicals that fits nicely alongside endorphins, the stuff that is released during and after a run or playing sport and gives you that sugar high often lasting the entire day.

Put the two together, training or running in the sun, and you’ve got a huge, almost addictive hit.

Vitamin D is also really important for keeping your bones strong and helping to reduce the risk of stress fractures, and it also helps muscle growth improving speed and strength. It’s a pretty important vitamin that doesn’t just make you feel that bit more active.

But at this time of year you’re being starved of it and it will undoubtedly be affecting your training and performance.

It’s the reason that many top football clubs are happy for their players to disappear to sunnier climates mid-season and likely to be why Newcastle United took their players over to Dubai for a warm-weather training camp – that’s how important vitamin D is to performance and boosting energy levels.

Should all the clubs do it? Maybe. In countries such as Italy (where there is a mid-season break in December), clubs head off for training camps to the southern hemisphere in search of sunlight and vitamin D every year.

I remember when I was in Florida in December one year, AC Milan were at Disney’s Wide World of Sports Complex.

So much for a ‘winter break’. It seems that a winter break is best described as a break from the long dark nights. It’s not a break in the traditional sense of having a rest.

And with so many of clubs abroad doing it in France, Spain, Italy, etc, it’s not hard to see why their national teams are much more successful than ours.

It’s so important to these top players and clubs that it isn’t uncommon for players every 8-12 weeks to have a blood test to monitor their levels of vitamin D.

It’s tiny, tiny differences like this that clubs are looking for to ensure their players hit top performance. I’ve even heard of players using artificial tanning beds to get their hit of it too.

Next time you see a top Premier League player looking suspiciously orange in January, you’ll know why.

But blood tests, artificial tanning booths and mid-season southern hemisphere tours come at a price. One often not able to be afforded at the grassroots level so you need to look for other options, and there are many.

Foods such as oily fish, liver, eggs and milk all contain vitamin D and even something as simple as a brisk 15-20 minute walk on your lunch break when the bright winter days appear will also help.