Seasonal Affective Disorder (SAD) is a depressive disorder that is differentiated from other forms of depression by a pattern of symptoms that flare up during a particular season of the year. This most often occurs in winter, especially in northern climates, when there are fewer daylight hours and people have lower exposure to natural sunlight.

Some functional medicine approaches can successfully reduce or eliminate the debilitating symptoms associated with SAD.


Researchers believe this “feel good” hormone plays a major role in depression. Low levels can contribute to mood changes, sleep disturbances, and appetite changes. Serotonin release can be enhanced with amino acids, such as theanine and tryptophan. Healthy serotonin function can also be supported by eating a healthy diet, exercising, and prioritizing good sleep. (see: 8 Foods to Boost Serotonin and Improve Mental Health).

Vitamin D.

This vitamin is produced when the skin is exposed to sunlight; as a result, in many places Vitamin D levels are more likely to be low in the winter. Vitamin D activates the enzyme that starts the pathway to produce serotonin. Low levels have been associated with increased risk of depression. If a person is unable to get good sunlight to skin exposure, vitamin D3 should be used as a supplement. I typically recommend optimizing 25-hydroxy vitamin D levels, with a goal of over 50 ng/ml.


This sleep hormone is produced in the pineal gland of the brain as a response to darkness. It is supposed to go up at night and down during the day. During the short, dark days of winter, more melatonin is produced, which can bring daytime fatigue and tiredness. This cyclical production of melatonin can be improved by exposing the eyes to direct daylight soon after waking up – sunlight, but not staring at the sun! Open window shades and, if possible, try to get outside for 10 minutes. Sun lamps may also be helpful, especially when used soon after waking up.

Food Choices.

Ultra-processed foods and those with high amounts of added sugar increase the likelihood of depression. Anti-inflammatory diets can reduce depression. These healthy dietary guidelines focus on ingesting whole foods, high fiber foods, fermented foods, prebiotic foods, high intake of produce with all colors in the food rainbow, high quality protein, and low mercury fish that is high in omega-3 fatty acids.

Additional Nutrients.

Besides vitamin D, depression can be lessened with good intake of other nutrients. B vitamins can be helpful. I often recommend getting a methylation genetic panel to make sure the right forms of B vitamins are consumed. There should also be good intake of magnesium, zinc, iron and vitamin C.

For those of you in cold, gray winter climates, I hope these tips give some practical guidance for avoiding the winter blues.

Hope you are having a wonderful holiday season and happy new year!

Dr. David


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