The holidays have come and gone, leaving us with new gifts, resolutions, and memories. Unfortunately for some, fall/winter festivities are accompanied by underlying bouts of seasonal depressive episodes. Seasonal Affective Disorder (SAD) is a recurrent depressive or bipolar disorder that occurs predominately during the fall and winter months and remits during spring and summer.³ A direct cause and effect relationship has not been established, but research suggests that inadequate light, hormone regulation, and physical work capacity (PWC) may be related.^1,5

It has been reported that up to 10 percent of people suffer from mild bouts of SAD, a subtype of major depressive or bipolar episodes.⁵ It is most commonly found in women in their 20’s and 30’s, but adolescents and men are not immune.³ Symptoms of winter SAD include increased need for sleep, increased appetite (particularly carbohydrate cravings), weight gain, lethargy, and isolation.^3,4

Initial treatment of SAD differs from general depression. Bright light treatment is recommended as the primary therapy. Two hour daily sessions of 2500 lx of artificial light at eye level for 1-2 weeks has been found to provide the most consistent decreases in depressive symptoms for winter SAD. Cognitive-behavioral and drug therapies may be effective as well.³ Various types and doses of pharmacological and psychological treatments are prescribed for symptom relief for both general depression and anxiety. Exercise is an additional behavioral intervention which has been recognized as a practical primary or complimentary treatment that triggers positive physical, as well as psychological responses. Numerous studies have established exercise-depression relationships that lead to positive disease outcomes. According to some research, exercise relieves or alleviates symptoms at a relative risk comparable to psychotherapy.¹

In this recent review of articles:

• Participants were assigned a 10-week intervention of exercising, exercising and therapy, or cognitive therapy only. There was no significant difference amongst the 3 groups. Each group displayed a similar reduction in depression.¹
• A study by Blumenthal at el. assessed 3 groups of moderately depressed adults and stratified them into exercise, medication, or exercise and medication groups. Though there was a quicker response to medication, at 16 wks each group had similar remission rates, 60.4 (exercise) vs. 68.8 (medication) vs. 65.5 (combination). Furthermore, a 10-month follow-up showed that the exercise group members maintained lower rates of depression compared to those taking medication.¹
• Farmer et al. used data from the National Health and Nutrition Examination Survey (NHANES I) to prove that lower levels of physical activity predicted depression in white women after a 8-yr follow-up.²

Are results related to dose? National physical activity guidelines (2008) recommend ≥ 150 minutes of moderate to vigorous aerobic activity per week and strength training at least twice a week in order to receive optimal health benefits. Based on exercise-depression dose response research, an initial exercise prescription of 20 minutes a day, 3 times a week is an adequate amount of physical activity to lead to reduction or alleviation of depressive symptoms. A 50% reduction in symptoms during treatment is considered clinically relevant.¹ A review by Dunn et al. cited eight of eighteen studies that showed a reduction in depressive symptoms by at least 50%.² Though some studies may not obtain a reduction rate of 50%, improvements with lower percentages can still be quite significant clinically. Mechanisms responsible for the exercise-depression relationship are still be in question, but whether it is the product of increased endorphins (Endorphin Hypothesis), increased core body temperature (Thermogenic Hypothesis), increased brain neurotransmitters (Monoamine Hypothesis), increased self-efficacy (Self-Efficacy Hypothesis) or merely a psychological distraction (Distraction Hypothesis), it has been proven that it is a practical adjunct treatment for general depression or anxiety.¹

1. Craft LL, Perna FM. The Benefits of Exercise for the Clinically Depressed.  J Clin Psychiatry. 2004;104-111.
2. Dunn AL, Trivedi MH, O'Neal HA. Physical Activity Dose-Response effects on outcomes of depression and anxiety. Med  Sci  Sports Exer. 2001; 33 S587-97.
3. Partonen T, Lonnqvist J. Seasonal affective disorder. The Lancet. 1998; 352: 1369-74
4. Rosenthal NE, Carpenter CJ, James SP, Parry BL, Rogers SL, Wehr TA. Seasonal affective disorder in children and adolescents. Am J Psychiatry. 1986; 143: 356-8
5. Saeed, SY, and Timothy Bruce. "Seasonal Affective Disorder." UptoDate. 28 Apr. 2009. Web. 20 Jan. 2011.