Colder and shorter days in the wintertime take their toll on the mood of all of us. During the winter months, it is not uncommon to notice that staff are less motivated, find it harder to start work in the morning and are "on edge", being more sensitive to work-place stress and experiencing frequent mood swings. That people have "a shorter fuse" and less energy in the winter influences the effectiveness of the individual staff member as well as the team as a whole.

In fact, these winter downs are part of a well-studied psychological phenomenon, the so-called Winter Depression, a mild form of what workplace health experts call Seasonal Affective Disorder (SAD). The most common symptoms of the Winter Depression among white-collar staff are:

• Boredom, tiredness, weakness;
• Increased sensitivity to stress;
• Difficulty getting up in the morning;
• Lack of motivation and focus.

Most of these symptoms are caused by a lack of natural light. In winter, days are shorter, the light of the sun is weaker, often filtered by a cloudy sky, and because of dropping temperatures we spend more time indoors. Moreover, natural sunshine is also an important source of vitamin D. Finally, also due to the holiday season, many people do less exercise and take in more sugar at this time of year. In a natural environment, mammals prepare for winter food shortages or hibernation, and the relevant reaction of the body is to increase body weight to build up reserve energy for the organs. In urban life, however, these stockpiles cause more health problems and depression than a feeling of security.

Since at the workplace one is expected to be just as active in winter than in other seasons, workplace health experts suggest the following to balance seasonal changes and the resulting Winter Depression:

• Expose yourself to natural light as much as possible: this may include taking a walk outdoors at lunch break (even if it's cold!).
• Use as much natural light at the workplace as possible, for instance by moving your desk to the window.
• Use early morning hours more than late evenings for extra work.
• On weekends, do light physical activity outdoors, preferably in the morning or early afternoon.
• Try to balance your diet. Winter holidays such as Christmas and New Year may put too much pressure on your stomach!
• You may also want to increase your intake of vitamin D from natural sources, such as milk, fish, eggs, butter, margarine or cod fish oil.