Seasonal Affective Disorder (SAD)

Seasonal affective disorder (SAD) is a form of depression that occurs during the same months of the year, each year. The majority of those with SAD experience this depression during the autumn and winter months, but SAD may also affect persons in spring or summer months.

  • Overview
  • Action Plan
  • Ask The Doctor
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Seasonal affective disorder (SAD) is a common phenomenon seen all around the world, but a slightly higher risk is seen in higher latitude areas of the world. The prevalence of SAD is approximately 5% in the U.S.,1 but subclinical levels of SAD are much more prevalent. The main hypothesis for the cause of SAD is the decreased sunlight exposure leading to a decrease in serotonin activity, which affects mood. Symptoms of SAD may include a seasonal pattern of:

  • Sadness
  • Emotional sensitivity
  • Increased sleep
  • Increased appetite (particularly to carbohydrate-rich foods)
  • Increased weight (from overeating)
  • Physical fatigue
  • Decreased appetite and insomnia (in those with spring or summer SAD)

Too much sunlight may be potentially harmful, but we now know that not getting enough outdoor sunlight decreases our vitamin D levels in our body and can affect our mood, however, there are natural strategies that may help individuals with SAD. Even a poor diet could worsen the depression associated with SAD, as fast-food and commercial baked goods have been linked to depression.2 A Nutritarian eating style is supportive for those with SAD.

  1. Kurlansik SL, Ibay AD. Seasonal affective disorder. Am Fam Physician 2012, 86:1037-1041.
  2. Sanchez-Villegas A, Toledo E, de Irala J, et al. Fast-food and commercial baked goods consumption and the risk of depression. Public Health Nutr 2012, 15:424-432.

Action Plan


  • A diet high in whole plant foods, such as a Nutritarian eating style which is high in micronutrients and other healthy fats, supports brain function and may reduce depression1 as it assures a decreased chance of deficiency in any nutrients and avoids potentially harmful foods that may negatively harm the brain, such as processed foods and excessive amounts of animal products.
  • In some cases, deficiencies in B vitamins, including folate and vitamin B12, omega-3 fatty acids, or other deficiencies may cause or worsen depression, so a balanced approach to a Nutritarian eating style in conjunction with a supplement regimen that includes sufficient amounts of zinc, iodine, vitamin B12, vitamin D, and DHA and EPA (omega-3 fatty acids) is recommended.

Light therapy/Bright light therapy

Light therapy is the preferred treatment for SAD2 as it is a safe and effective method to help reduce depressive symptoms. This light may be from careful exposure to sunlight or from a specialized lamp. Morning light exposure is most effective.

Omega-3 fatty acids

Supplementing DHA and EPA has been shown to be useful at lowering the risk of developing SAD.3 It is also helpful for non-seasonal depressive symptoms and may be a safer alternative to medications.

Other Considerations

Therapy or counseling may be important depending on the severity and circumstances, just as in any form of depression, in conjunction with these lifestyle changes to get the best results.

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  1. Akbaraly TN, Brunner EJ, Ferrie JE, et al. Dietary pattern and depressive symptoms in middle age. Br J Psychiatry 2009, 195:408-413.
  2. Kurlansik SL, Ibay AD. Seasonal affective disorder. Am Fam Physician 2012, 86:1037-1041.
  3. Magnusson A, Axelsson J, Karlsson MM, Oskarsson H. Lack of seasonal mood change in the Icelandic population: results of a cross-sectional study. Am J Psychiatry 2000, 157:234-238.

Ask The Doctor

The following are sample questions from the Ask the Doctor Community Platinum and higher members can post their health questions directly to Dr. Fuhrman. (All members can browse questions and answers.)


I suffer from Seasonal Affective Disorder, which seems to be at its worst during the winter months. I know not to ingest stimulating foods, such as coffee and tea, as they do play a part in my melancholia, but what other foods should I avoid? And, do you have any other tips for overcoming SAD during particularly hard times of the year?


As far as foods to avoid, it comes down to eating a high nutrient diet and avoiding the processed, refined foods, including sugar and caffeine, and minimizing animal products to less than 10 percent of total calories. Take the supplements I recommend to avoid deficiencies in B12, Vitamin D, and DHA, and get plenty of sunshine. It is important that the exposure to sunshine occur at the same time each day, first thing in the morning. When this is not an option, I recommend light therapy with a therapeutic light designed for this purpose.