Seasonal Affective Disorder (SAD)


Seasonal Affective Disorder (SAD) is a specific depressive condition commonly encountered by 3% of our general population in winter, and occurring in 10% of depressed patients. SAD is a mood disorder associated with depression episodes and related to seasonal variations of light. As seasons change, there is a shift in our “biological internal clocks” or circadian rhythm, due partly to these changes in sunlight patterns. This can cause our biological clocks to be out of “step” with our daily schedules. The most difficult months for SAD sufferers are January and February, and younger persons and women are at higher risk.

Symptoms of SAD Include:

  • regularly occurring symptoms of depression (excessive eating and sleeping, weight gain) during the fall or winter months.
  • full remission from depression occur in the spring and summer months.
  • symptoms have occurred in the past two years, with no nonseasonal depression episodes.
  • seasonal episodes substantially outnumber nonseasonal depression episodes.
  • a craving for sugary and/or starchy foods.

Possible Cause of this Disorder

Melatonin, a sleep-related hormone secreted by the pineal gland in the brain, has been linked to SAD. In order to induce sleep at night, the levels of this hormone increase in the dark. But when the days are shorter and darker the production of this hormone remains high during daytime, causing symptoms of sleepiness and depression. Due to their increased travel time, often leaving their home when it is dark and returning when it is dark, Mississauga residents have little sunlight exposure, further increasing their levels of melatonin.


To prevent protect yourself from these effects and for mild symptoms, spending time outdoors during the day or arranging homes and workplaces to receive more sunlight is helpful. Lunch hour strolls outside are a great way to increase your sunlight exposure, get some exercise, and discharge the stress accumulated at work. One study found that an hour’s walk in winter sunlight was as effective as two and a half hours under bright artificial light. Phototherapy or bright light therapy has been shown to suppress the brain’s secretion of melatonin.

If these preventive walks don’t work, there are many natural therapies that can alleviate mild to moderate depression, for serious depression antidepressant drugs may be required. Discuss your symptoms thoroughly with your Naturopathic Doctor, family doctor and/or mental health professional.

Submitted for publication to the Mississauga News, 2003.

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