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Darker Days Trigger Seasonal Depression, Experts Explain Why

As clocks fall back and afternoons darken, researchers explain why seasonal depression hits and what actually helps.

By Dr. Josh Axe · November 6, 2026 · 2 sources · Watch

Photo: Pexels

ABC News reported on November 4, 2026, that millions of people with seasonal affective disorder, or SAD, are bracing for darker afternoons now that clocks have shifted to standard time across much of the U.S.

People prone to seasonal depression feel it as daylight shrinks and clocks fall back to standard time. SAD was first described in 1984 by Dr. Norman Rosenthal, then at the National Institutes of Health; a milder subsyndromal form and a less-understood summer variant are also recognized. According to the NIH, SAD affects many more women than men, with symptoms such as persistent hopelessness and trouble concentrating, remembering or making decisions.

Kathryn Roecklein at the University of Pittsburgh found that people with SAD, on average, responded less to blue light than people without it, most of all in winter. Dr. Paul Desan of Yale's Winter Depression Research Clinic said many people with SAD respond to light therapy: about 30 minutes each morning with a light near 10,000 lux, about 20 times brighter than regular indoor light. Lights run from $50 to more than $400, and Desan said some are too dim to do much good.

Specialized cells in the eye turn the blue light in sunlight into signals that activate the brain's alertness centers, bringing wakefulness and possibly better mood. Roecklein's finding suggests one possible cause of winter depression. Antidepressants are a first-line treatment alongside light therapy, and University of Vermont researcher Kelly Rohan said cognitive behavioral therapy has more durable effects, since light therapy's benefits can fade once people stop.

I believe that because it is easy to remember, the acronym has stuck,

Dr. Norman RosenthalABC News, November 4, 2026

No single cause has been identified, less is known about the summer form, and the blue-light finding is an association from one research group's testing, not proof that low sensitivity causes SAD.

Dr. Axe’s Take

How your eyes and brain respond to light plays a real role in seasonal depression. I'd get outside within an hour of waking, even under clouds, and let morning daylight reach your eyes for a sustained stretch rather than leaning on a lamp alone. Keep sleep and wake times fixed through winter, since a wandering schedule makes the brain's light-timing system work harder. Outdoor movement, even a cold walk, adds to the benefit. And listen, never stop or change a medication on your own. Make that change with your practitioner. For symptoms that persist, talk therapy has shown more lasting results than light alone.

— Dr. Axe

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Story summary

Who: People with seasonal affective disorder (SAD), reported by ABC News on November 4, 2026
Design: News report summarizing SAD research, including a blue-light sensitivity study by Kathryn Roecklein at the University of Pittsburgh
Dose: Light therapy: about 30 minutes each morning from a device near 10,000 lux
Primary result: People with SAD showed lower sensitivity to blue light than others, especially in winter months
Secondary: Light therapy benefits reported to fade after stopping; cognitive behavioral therapy reported to have more durable effects
Date: Nov 4, 2026