Seasonal Affective Disorder: The Evidence-Based Supplement Protocol

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Seasonal affective disorder (SAD) is recurrent winter-pattern major depressive episodes. Bright light therapy (10,000 lux for 30 minutes morning) is the foundational intervention with the strongest evidence — comparable in effect size to SSRIs for the seasonal pattern. Supplements have an adjunctive role.

Vitamin D — Repletion to 30+ ng/mL

Vitamin D status correlates with mood in SAD cohorts and many patients are deficient by midwinter. Repletion improves mood in deficient SAD patients but does not consistently outperform placebo in already-replete adults. Test and treat. See vitamin D piece.

Light Therapy — The Gold Standard

Not a supplement but the highest-evidence intervention. 10,000 lux full-spectrum light box for 20–30 minutes within 1 hour of waking, daily from autumn through spring. Effect size comparable to SSRIs. Mention here because any supplement protocol for SAD that omits light therapy is fundamentally incomplete.

EPA-Dominant Omega-3, 1–2 g EPA Daily

Omega-3 has positive evidence in depressive disorders broadly. SAD-specific trials are smaller but consistent with the broader signal. See omega-3 depression piece.

Saffron, 30 mg Daily

Saffron has antidepressant evidence in non-seasonal MDD; SAD-specific data is more limited. Reasonable adjunct in mild-moderate seasonal symptoms. See saffron piece.

Melatonin — Phase-Shifting, Not Mood

Low-dose melatonin (0.3 mg afternoon) has been studied for phase-shifting circadian timing in SAD. Not a mood intervention per se but addresses one mechanistic component. See melatonin dosing piece.

What NOT to Take

Avoid St. John's Wort + SSRIs simultaneously — serotonin syndrome risk. Skip "winter blues formula" megaproducts with subclinical doses. Avoid 5-HTP if on any serotonergic medication. Don't replace SSRI or light therapy with supplements in moderate-severe SAD.

How to Run the Protocol

Bright light therapy 10,000 lux × 30 min morning, daily Oct–April. Vitamin D to repletion. Omega-3 1.5 g EPA daily. Outdoor time, even on overcast days (outdoor "cloudy day" light still exceeds indoor by 10×). If symptoms remain moderate-severe, SSRI (bupropion XL has the only FDA SAD-specific indication) or psychiatry referral. See SAD condition page.