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 are having 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.

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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 sport and gives you a 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. So 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 clubs are happy for their injured players to disappear to sunnier climates mid-season if and when injuries happen. A couple of seasons ago Wayne Rooney was sent to America to recover from his foot problem and was in the news for ordering chicken nuggets and chips from his luxury hotel in Dubai. The facilities at the training camps in the USA or the Middle East are certainly no better than here in the UK, it's just the sun shines much brighter and longer and more and more top levels athletes and their medical teams are realising how important vitamin D actually is.

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. Just recently in December I was working with one of the Soccer Camps I get involved with in Florida and AC Milan were on the next pitch to our training facility at Rollins College in Orlando every day. They also played a game at Disney's Wide World of Sports Complex.

So much for a winter break! It seems that a winter break is just that, a break from the long dark nights. It's not a break in the traditional sense of having a rest. And it blows out of the water the argument that rages every time England are dumped out of a major football tournament - that our players don't get the 'winter break' like the other countries do.

It's so important to these top players and clubs that it isn't uncommon for players every eight to twelve weeks to have a blood test to monitor their levels. It's 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. Next time you see one of the top premier league players looking suspiciously orange in January, you'll now 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 have vitamin D that give you a boost and reduce your injury risk, and even something as simple as brisk 15-20 minute walk on your dinner break each day when the bright winter days appear will also help.