Seasonal Affective Disorder

Today’s post is another excerpt from “Best Weight: A Practical Guide to Office-Based Weight Management“, recently published by the Canadian Obesity Network.

This guide is meant for health professionals dealing with obese clients and is NOT a self-management tool or weight-loss program. However, I assume that even general readers may find some of this material of interest.


Seasonal affective disorder (SAD) is a recurring depression with seasonal onset and remission. SAD primarily occurs in the winter months and it is postulated that the decrease in daylight hours alters circadian rhythms and affects melatonin and serotonin levels.

A number of factors distinguish SAD from major depressive disorder. Especially important here is that SAD is often associated with increased rather than decreased appetite.

There are two primary treatment modalities for SAD. Light therapy involves exposure to visible light that produces a minimum of 2,500 lux at eye level. Daily treatment duration depends on the intensity of the light: two hours a day are needed with a light emitting 2,500 lux, while 30 minutes a day is sufficient with 10,000 lux. Light therapy devices are readily available in specialty health-care stores and on the Internet. SAD can also be treated with pharmacotherapy using antidepressants in the same way one would treat non-seasonal depression.

To date, no study has demonstrated additional benefit from combining light therapy and pharmacotherapy.

© Copyright 2010 by Dr. Arya M. Sharma and Dr. Yoni Freedhoff. All rights reserved.

The opinions in this book are those of the authors and do not represent those of the Canadian Obesity Network.

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