‘Blue’ light found to be most effective in combating seasonal affective disorder

I was out last night with a friend, and he mentioned his mother’s depression. Seeing as we’re now deep into the autumn here in the UK, I asked if there was any seasonal component to this. There is. Like a lot of people, his mother’s mood takes a distinct turn for the worse in the winter. I suggested that he might consider a light therapy device to supplement the light his mother won’t be getting much of in the autumn or winter.

By coincidence, just yesterday I had been spying my own light-box on top of a filing cabinet in my office at home, wondering whether the time was right to crack it out and get using it this year. I actually started using it again today.

The device I have is a compact little number that I bought last winter. It gives off blue light. I feel it really helped maintain my mood and energy during the darker months. Unusually for me, I didn’t do any research at all before buying it. I bought it on the recommendation of a patient of mine. I had recommended light therapy to her, and she had then gone and done some research of her own. Being a thoughtful soul, she returned to my clinic some time later and presented the results of her research.

I remember her making the point that her research had revealed that light in the blue part of the light spectrum appeared to be most effective in dealing with light-related mood issues. I trusted this lady enough not to need to go and double-check this before purchasing the device she recommended.

This morning, though, I thought I’d do a bit of retrospective research regarding light therapy. Is blue light really best for treating seasonal affective disorder (SAD)? I came across a study published earlier this year in the journal Depression and Anxiety in which individuals with seasonal affective disorder were treated with blue light (of about 470 nm) with red light daily, for a period of 3 weeks [1].

60 per cent of those treated with blue light responded favourably to treatment, compared with only 13 per cent of the red light-treated group.

In the blue-light treated group, overall ratings of depression dropped by 51 per cent, compared to a 32 per cent improvement in those treated with red light.

The individuals in the study group were made up of those with SAD, as well as those with SAD in conjunction with symptoms of depression at other times in the year. Perhaps not surprisingly, those with SAD only responded better than those with more perennial depression.

In another study I found, this one from 2006, blue light outperformed red light in the treatment of SAD [2].

There does indeed seem to be evidence that light from the blue part of the light spectrum is generally most effective for treating SAD. This might be worth bearing in mind if you’re contemplating purchasing a light therapy device or considering replacing an existing one.


1. Strong RE, et al. Narrow-band blue-light treatment of seasonal affective disorder in adults and the influence of additional nonseasonal symptoms. Depression and Anxiety 2009;26(3):273-8

2. Glickman G, et al. Light therapy for seasonal affective disorder with blue narrow-band light-emitting diodes (LEDs). Biological Psychiatry 2006;59(6):502-7

9 Responses to ‘Blue’ light found to be most effective in combating seasonal affective disorder

  1. Jack 14 October 2009 at 9:17 pm #

    Dr. Briffa,

    Is the helpful nature of visible blue light likely because of its impact on modulating melatonin production? As far as I know, the less visible blue light reaching the suprachiasmatic nucleus, the greater the melatonin production by the pineal gland. And while this is usually mentioned with reference to those who may have sleep iss

  2. Charles 15 October 2009 at 1:45 am #

    I have one of those blue light devices as well, and have had good results with it.

    One of the aspects that made it work for me, I think, was that they have a questionnaire on their web site that asks you a series of questions, and then gives you a recommendation as to how and when to use the light.

    Surprisingly, the recommendation for me was to use it at night, about an hour before bed time. And when I did, I definitely slept better.

    The plural of anecdote ain’t data, but this is definitely worth a try.

  3. PJ 15 October 2009 at 6:30 am #

    This guy (Ghadiali) was huge into ‘light therapy’ nearly a century ago. Like many in that era he was pretty much eradicated and you now find it mostly under quack accusations. I read the full court transcript of a hearing they had against him once–it was fascinating (especially the way they actually failed to have anything workable against him so the judge just made up something else they could try for and keep going, several times, LOL). He was pointing out that light actually *does* affect physical matter; some chemicals explode with a certain color of light, and darkrooms use red light for good reason, etc. They had an engineer testifying against him and he actually won the guy over lol. I had a rather amazing incident with my poisoned cat, over a long weekend when I had no cash, who was clearly dying. She and the other cat were quite obviously “aware” of the light colors and preference and dragged herself into and out of the light and I’d change it at that point (I felt stupid that it all just seemed like colored light to me! It clearly wasn’t to her). She survived; obviously no control group here, but it impressed the hell out of me, mostly her behavior with the colors. This is the book with Dinshaw’s original suggestions. I might add that they were prevented from giving away the color frequencies but a friend of mine was able to talk with a man personally and get recommendations for specific panels from a mfg company (he gave me some). Book is here:
    None of this is “proved” and is considered ‘quackery’. Until or unless science gets around to researching this though, I doubt it will be any more or less ‘real’ in effects, we’ll just understand or believe more or less of it. Anyway thought you might be interested.

    A note on SAD: I’m light-olive skinned, grew up in Coastal CA. Never knew about SAD till I moved to seattle and was near suicidal. A friend sent me a full spectrum bulb I kept on all the time and it chirped me right up. But I’m wondering, is it possible that a reduction in Vitamin D3 could be part of this? Because when I first took D3, about 6 hours later I felt this profoundly increased “sense of well-being” for lack of any other way to put it. I didn’t know I had been depressed until I wasn’t anymore, in that case. Just makes me wonder.


  4. Tim 30 October 2009 at 7:23 pm #

    Is there any link to Vitamin D deficiency and SAD, or is it the light waves specifically that are therapeutic

  5. Tina CD 11 November 2009 at 11:58 pm #

    Great blog! I live in Oregon and have developed SAD over the years. I started using an Apollo blue light 4 winters ago with great success. I use it 5 times a week in the morning (at work) for about 20 mins. Usually starting in Oct and until late Feb. I sometimes do an additional 20 min session in the late morning around Christmas when the daylight is the lowest. I am more awake in the morning, not groggy in the evening and generally happier.

    Each fall it takes about 1-2 weeks of lamp use for me to notice the effects. If I stop using the lamp for whatever reason and start up again, it takes only 3 days for me to feel good again.

    I have also heard that lack of Vitamin can increase your likelihood of SAD. I wondered if mood lights in general somehow worked to help us product V D like the sunlight did. But not the case at all. So a VD supplement is strongly recommended.


  6. Child Psych 20 November 2009 at 6:00 am #

    Hi – Just wanted to tell you I included your post in a roundup about SAD on my blog. I hadn’t heard about the color of the lights making a difference before–thanks for including your own experience! I also wonder about the Vitamin D connection but haven’t researched it yet. I found some other interesting articles to include about SAD. See Mental Health Roundup: Seasonal Affective Disorder | Child Psych

  7. Douglas Cootey 20 November 2009 at 11:03 am #

    Do you think there’d be a difference between blue light and full spectrum light? I would think that the “full” part of full spectrum would be inclusive of blue light, but I was wondering if you know of any tests on the subject. I use full spectrum CFLs in my ceiling lights in the rooms I work most in as my light therapy. I find it very effective. I wrote about my experience here:



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