On the Frontiers of SAD: How Much Light is Enough?

“Mehr Licht!” cried out Goethe, the great German writer, as he was dying, “More light!” In these two words he encapsulated (albeit inadvertently) the essential principle underlying the major treatment for seasonal affective disorder (SAD). But one question that has dogged researchers since we first described SAD and developed light therapy is: “How much light is enough?”

In our first studies at that National Institute of Mental Health, we found that light fixtures that emitted 2500 lux (a measure of light intensity) were superior to control fixtures that emitted only 300 lux. Subsequently, Michael and Jiuan Su Terman at New York Psychiatric Institute found that 10,000-lux fixtures were even better than the 2500-lux variety. Since then, 10,000-lux light fixtures have become the industry standard, widely advertised for treating Seasonal Affective Disorder and other ailments.

But these lux measurements are by no means the only guide to the value of a light fixture. Measurements are taken by a light meter at a point in space – so a teeny weeny light fixture might register the same lux measurement (say, 10,000 lux) at a certain point in space same as a huge light fixture might register at a different point. Does that mean that these two light fixtures are equally effective for treating Seasonal Affective Disorder? Believe it or not, that is one research question that has never been studied – though it certainly should be. Common sense, however, and extensive clinical experience suggest that they are not equivalent. That is why I routinely recommend larger light boxes, especially for those with more severe SAD symptoms.


In my book Winter Blues, I have shared my morning light routine with my readers: A dawn simulator, which gradually turns on the bedside lamp on a winter morning to simulate an early summer dawn; then a large light box perched on a stand next to the bed comes on automatically, and I bathe in its rays as though I am lying on a beach somewhere, until it is time to get my day started. Now, earlier in the winter, all these measures and more (light therapy during the day, Transcendental Meditation, exercise, yoga) were inadequate – so I took the ultimate SAD cure. I headed for the sun in the Bahamas (see my post on the Bahamas and Winter Blues). The phrase “died and gone to heaven” comes to mind, though it was more like going to heaven and coming alive. After I returned home, I felt great for a while, but the dark days reasserted themselves, my spirits began to sink, and it was time for another creative solution.

I thought back to the Bahamas and wondered: What is it about the sun and the sky that a light fixture just doesn’t replicate. Well, lots of things, of course. But I recalled standing on the balcony and looking out at the panorama – the beach and the ocean — suffused with sunlight, and could almost feel the serotonin pouring onto my brain like butterscotch. How could I possibly replicate it? Well, if one light box is 22 inches wide, I calculated, well three light boxes would be – you guessed it – 66 inches wide. Not exactly the Bahamas, but at more than 10 square feet of intense light, definitely worth a shot.


Bottom line: It’s made all the difference. I feel great again. And now that the days are getting longer, I can quote Shelley’s famous lines, “If winter comes, can spring be far behind?” and actually mean it. A friend of mine has used three light boxes in a different array – one in front and one at a 45 degree angle on each side – and claims great success with that arrangement. These results should not be surprising. After all, many medications (antidepressants included) work better at higher dosages. Why not light therapy?

A word of caution:

Light therapy, like all active treatments, can have side-effects – such as headaches, eyestrain, insomnia and even hypomania, especially if used late at night. Many treatments result in more side effects when the dosage is increased – and light may be no exception in this regard. Therefore I do not recommend using more light therapy than is prescribed in the standard literature, including my book Winter Blues. I do believe, however, that an educated consumer is a doctor’s best customer so, if you are working with your doctor and have come up against a brick wall as far as your SAD is concerned, one thing to consider is Goethe’s dying words – “Mehr Licht, More Light!”

Wishing you Light and Transcendence,


Click to purchase Winter Blues


4 Replies to “On the Frontiers of SAD: How Much Light is Enough?”

  1. Cyndi J. Landsrud says:

    In the 90’s I was in one of your research studies on S.A.D. @NIH.It was a fun experience. Although I was supposed to get to keep my light box, Paul Schwartz, MD asked me to bring it back as they were short. Bummer. Living in Seattle now, SAD rears it’s ugly head often. This winter I’ve been taking a liquid Coenzyme Q10. No SAD symptoms for the first time ever…..WOW!!! In your study, I was patient Cynthia J. Moe

  2. Tanya says:

    Hello- my question would be how long do you use the light therapy daily and if the SAD symptoms reappear, how long will light therapy take to be effective? Days, Weeks???

  3. Toine Schoutens says:

    Hello Norman,

    Maybe the article below is helpfull:

    Light therapy: Methodological issues from an engineering perspective



    Toine Schoutens

  4. Kev Cousin says:

    Hi, I have Diamond 4 light box and it does make all the difference but what I have found works is a very good quality Vit D spray. the one I use id from Physica Energetics called Solray D, and purchased from Sai Nutrition in London. It is vitamin D3 in an MK7 format. I also supplement with 5HTP. Since I started with both last august I only went on my light box 3 times last winter. I like the idea of 3 boxes though. Regards


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