"There's no known way to prevent the development of seasonal affective disorder. However, if you take steps early on to manage symptoms, you may be able to prevent them from getting worse over time. Some people find it helpful to begin treatment before symptoms would normally start in the fall or winter, and then continue treatment past the time symptoms would normally go away. If you can get control of your symptoms before they get worse, you may be able to head off serious changes in mood, appetite and energy levels"

www.mayoclinic.org