Light Therapy for Seasonal Mood Changes: What the Evidence Shows
Seasonal Affective Disorder becomes more relevant as routines change in midlife. Here’s what the research actually supports about light boxes.
Reviewed against NIH & PubMed research. Updated July 2026.
ⓘ Pending expert review: This guide was written and cited from published research as a reference starting point. It has not yet been reviewed by a credentialed medical professional. Treat it as background reading, not clinical guidance, until our review badge appears here.
How does light therapy work?
Bright light exposure, particularly in the morning, helps regulate circadian rhythm and has direct effects on mood-related neurotransmitters. It’s one of the better-studied non-medication interventions for seasonal affective disorder (SAD), with clinical trial support comparable to some antidepressants for seasonal-pattern depression specifically.
What specs actually matter when choosing a light box?
Look for 10,000 lux output (the standard used in most clinical trials), and use it at a proper distance and angle (usually 16-24 inches away, not requiring you to stare directly at it) for 20-30 minutes each morning.
How long before it works?
Many people notice improvement within 1-2 weeks of consistent morning use, though some research suggests benefits can continue building over several weeks.
Is light therapy just for seasonal depression, or does it help other sleep/mood issues too?
It’s also used for circadian rhythm disorders and some non-seasonal mood and sleep issues, though the strongest evidence specifically is for seasonal patterns.
Can light therapy be used alongside antidepressants?
Yes, often as a complementary approach, though this should be discussed with the prescribing doctor rather than combined without guidance.
What time of day should I use a light box?
Morning use, ideally within an hour of waking, is what most clinical trials use and is generally considered most effective for circadian regulation.
ⓘ Medical disclaimer: This guide is for educational purposes only. Talk to a doctor before starting light therapy, especially if you have bipolar disorder or an eye condition.