Background: Season-related subsyndromal depressive symptoms during winter are common among populations at high latitudes. Both physical exercise and exposure to bright light can relieve the fatigue and downturn of mood associated with the shortening length of day. Serum cholesterol level may be related to changes in mood, but the evidence is contradictory. Our objective was to compare the effect of aerobic exercise with or without bright-light exposure on health-related quality of life, mood, and serum lipids in a sample of relatively healthy adult subjects.
Method: A randomized controlled trial was conducted with subjects allocated to group aerobics training in a gym with bright light (2500-4000 lux) (N = 40) or normal illumination (N = 42) or to relaxation/stretching sessions in bright light as a control group (N = 42) twice a week for a period of 8 weeks. Changes in mood were recorded using questionnaires at the beginning of the study, at weeks 4 and 8. and at follow-up 4 months after the study. A blood sample was drawn before and after the 8-week intervention to measure the concentrations of serum lipids.
Results: Ninety-eight subjects completed the 8-week study. Both exercise and bright light effectively relieved depressive symptoms. Bright light reduced atypical depressive symptoms more than exercise (p = .03), based on the atypical symptoms subscore of the Structured Interview Guide for the Hamilton Depression Rating Scale-Seasonal Affective Disorders Version Self-Rating Format. There were no significant differences between the study groups in the changes in serum lipid levels.
Conclusion: Bright light administered twice a week, alone or combined with physical exercise, seems to be a useful intervention for relieving seasonal mood slumps.