Overview
- Seasonal affective disorder is a recurrent form of depression that typically begins in the fall and eases with longer spring daylight.
- Reduced daylight can disrupt circadian timing, prolong melatonin release, and lower serotonin activity, leading to fatigue, low mood, and sleep changes.
- Clinicians recommend daily morning outdoor light or a 10,000‑lux light box for about 30 minutes, with many people improving within weeks, and dawn‑simulating alarms can help recalibrate sleep‑wake cycles.
- Effective supports include consistent sleep and meal times, regular exercise, social connection, psychotherapy such as CBT, and medication when needed, and one cited study reports high relief rates when CBT is combined with other treatments.
- Estimates of how many are affected vary by source, women are reported to be affected more than men, and stigma and help‑seeking barriers—particularly for men—can delay care.