This is because, even in the depths of winter, daylight in some parts of Britain is up to 25 times brighter than the recommended lighting level for most offices and exposure to light is known to bring important health benefits.

The human body needs light – particularly in the mornings – to regulate its internal clock to keep it in tune with the 24 hour day-night cycle. Disruption to the body's biological clock, or circadian rhythms, has been linked to a variety of health problems including Seasonal Affective Disorder (SAD), sleep disorders, reduced immune function and
even cancer.

Research also shows that levels of serotonin, the important mood controlling brain chemical, change according to light exposure. Low serotonin levels are associated with depression, anxiety, insomnia and fatigue. Light therapy is sometimes used to treat non-seasonal depression and other mental health problems.

Dr Kam Dhillon, head of research at the Mental Health Foundation, says that a lack of light could be detrimental.

"Modern lifestyles keep many people indoors during the day, limiting exposure to daylight. During the winter it's quite common to travel to and from work in the dark and people may not be getting enough light during the day.

"Because a person's eyes adjust instantly to the light level wherever they are, it can seem gloomy outside and not worth the bother of leaving the house or office but light plays a vital role in regulating our bodily systems. For those whose mental health is affected during the autumn and winter months it's important to get as much exposure to daylight as possible."

For most people, the gloomy winter months can seem to drag on. For some, a lack of light during the winter is thought to cause SAD. But you can beat the winter blues by:

Getting outdoors during daylight as much as possible

Light therapy using specially designed "light boxes" has been shown to be effective in treating SAD symptoms.

Listen to your body – if you're a slower during the winter try not to overdo it.

Exercise and maintaining a balanced diet are excellent ways to look after your mental health. Outdoor exercise during daylight hours could be particularly helpful.