Fresh air and exercise usually help lift sagging spirits in the gloom of winter, according to a leading psychiatrist.

Frank Schneider, director of the Department of Psychiatry and Psychotherapy at Aachen University Hospital, claims lethargy and difficulty getting up in the morning are not unusual during the colder months.

"One reason for low spirits is that we spend less time out of doors and are less active in the winter," he told the German Press Agency dpa.

Mr Schneider also pointed out that bright light therapy has proven effective in helping people who may be suffering from Seasonal Affective Disorder (SAD) or 'winter blues', a primary cause of which is a shortage of daylight.

However, he added that getting fresh air and regular fitness training was generally enough to combat the problem.

Fitness trainer Jim Stubbs also recommends that one of the best things people can do to maintain emotional and physiological stability in winter is to take regular exercise.