Anchor Psychiatric Group

Light Therapy for Seasonal Depression: What Actually Works

Ready when you are.

Secure telehealth psychiatry for patients across the West. Request an appointment or call us with a question.

Request an Appointment
Meet Our Providers

By Stephanie Winter, DNP, FNP-C, ENP-C, PMHNP-BC — board-certified psychiatric nurse practitioner and owner, Anchor Psychiatric Group. Medically reviewed by Thomas Winter, MD.

Light Therapy for Seasonal Depression: What Actually Works

Light therapy is one of the most evidence-supported treatments for Seasonal Affective Disorder; but a lot of what’s marketed online gets the details wrong. If you’re going to invest in a light box, it’s worth knowing what actually makes one effective, because using the wrong one, at the wrong time, in the wrong way, won’t get you the results you’re expecting.

What to look for in a light box

  • Brightness: 10,000 lux. This is the level most studied and shown to be effective. Many lamps marketed for “mood” or “energy” are far dimmer and won’t do much.
  • Full-spectrum white light, not blue light. Despite how blue light is marketed for other uses, white light boxes are the standard for SAD treatment, and they carry less risk of eye strain with proper use.
  • UV-filtered. A quality light therapy box filters out UV light, so you’re not trading one problem for another.
  • Size matters more than people expect. A small box requires you to sit closer and more precisely positioned; a larger box gives more flexibility while you eat breakfast or work.

Timing is not optional

This is where a lot of people undermine an otherwise good light box:

  • Use it in the morning, ideally within the first hour of waking. Evening use can interfere with sleep by shifting your circadian rhythm the wrong direction.
  • 20–30 minutes is the typical effective dose at 10,000 lux, positioned about 16–24 inches from your face, off to the side (not staring directly into it).
  • Consistency matters more than any single session. Daily use through the darker months tends to outperform occasional use.
  • Give it 1–2 weeks before expecting to notice a difference. It’s not immediate, but for people who respond to it, the effect is often substantial.

Who should be cautious

Light therapy isn’t the right starting point for everyone. If you have bipolar disorder, light therapy can potentially trigger a manic or hypomanic episode and should only be used under a provider’s guidance, typically alongside mood-stabilizing treatment. If you have certain eye conditions or are on medications that increase light sensitivity, that’s also worth discussing with your provider before starting.

It’s usually one piece, not the whole plan

For a lot of patients, light therapy works best alongside other elements: consistent sleep timing, getting outside during daylight when possible, and sometimes medication adjustments timed to the season. Think of it as a strong tool in a broader plan rather than a stand-alone fix, especially if your seasonal symptoms have been significant in past years.

The bottom line

Done right – the right lux level, the right timing, used consistently – light therapy has real evidence behind it. Done as an afterthought, propped on a shelf and used inconsistently in the evening, it’s much less likely to help. If you’re not sure whether it’s right for you, or how to fit it into a broader plan, that’s exactly the kind of thing worth a conversation with your provider before winter sets in.

Want help building a seasonal plan that actually fits your life? https://anchorpsychiatricgroup.com/contact/ — we can talk through whether light therapy, medication timing, or both make sense for you.