We just passed the Autumnal Equinox, so time for some illuminating words for the wintery days ahead.

There’s a world of difference between being generally grumpy and full on clinical depression. Those who are moderately miffed do not need any treatment but a swift figurative kick to the backside and a brisk walk in the countryside or on a beach to get them back on track. Sufferers of the very real problem of depression, and its even more worrying cousin bipolar disorder (still commonly referred to as manic depression), need something less figurative, pharmaceutical intervention, usually to alleviate, or at least control, symptoms.

Then there is the fairly modern notion of the winter blues, seasonal affective disorder (SAD) as the medicalisationists prefer. What is it exactly? Many people don’t enjoy the “drawing in of the nights” as winter encroaches and the long, dark months of November through February with their significantly foreshortened periods of reduced solar luminance are enough to make anyone miserable. But, do humans somehow need exposure to full-spectrum daylight to be happy? There is a whole medical devices industry growing out of the notion that we do and it promotes desklamps that offer to light up your life, during the dark days, in ways that a conventional incandescent bulb, compact fluorescent tube or LED array simply cannot do.

I was intrigued then when a Cambridge-based company, Lumie, sent me a 55-Watt desk lamp that gives off bright “white” light with claims of treating SAD. To be honest, I don’t know if I suffer from SAD or indeed whether it is a real clinical condition, the list of symptoms is so long and overlaps so spuriously with any number of other “conditions” that I suspect SAD is a myth, especially as they talk about summertime SAD now too!

However, I do prefer the long, bright days of summer to the short stumpy bursts of sunlight we get in the Winter, but does that make me a sufferer? Lumie, the company that sent me the lamp to review, included a fairly simple questionnaire with the lamp that asks about depression symptoms, eating habits, weight gain and sex life as well as waking patterns. You’re to tot up your score on each question from 0 to 5 to determine whether you suffer from SAD (it’s more like a magazine-style Q&A than anything that would give scientifically valid data in a clinical trial, I feel). Then, you’re meant to fill in the questionnaire again after several periods of lamp use.

The 2 x 24 Watt bulbs used in the device are Made in China (and branded as ZLamp CF-L 24W/865)  just look like standard short mercury-vapour fluorescent tubes to me. They are bright. They are also quick to start up and so far flicker free. I don’t see anything on the manufacturer’s site to suggest there is anything particularly special about their CF-L tubes. The light spectrum emitted from fluorescent lamps is produced by a combination of light directly emitted by the mercury vapour and the excited phosphorescent coating that lines the tube. It doesn’t mention anything about the bulbs being “natural sunshine” type, which is odd as I believe it’s exposure to sunlight that is thought to be the critical issue in avoiding SAD. But, maybe that’s not the case it just has to be “bright” any light.

I asked Lumie’s Lindsay Stanley to expand: “The parts fitted within our lights are sourced to ensure they meet strict safety standards and regulations – simply purchasing CFLs ‘off the shelf’ would not ensure this, nor would this produce the required light level.” She also points out that, “All our lights filter out the UV to bring UV levels emitted from the CFLs well within the safe UV thresholds, using CFL’s alone would not do this. We also fit high frequency electronic ballast within the lights so that they do not cause uncomfortable flickering for the consumer. Because all of our products are independently measured and tested and are certified as a medical device, our consumers can rest assured that they are purchasing a product that will do what it claims to do.”

A recent paper does suggest that 40 minutes exposure to light therapy at 10,000 lux improves mood over a period of several weeks daily usage. There was a difference from those on 20 minutes daily and virtually no difference for anyone on 60 minutes daily, although they say a single session improves mood to some degree. But, the team also claimed to have seen a change in mood after the first test with their volunteers, which seems at odds with the need for several weeks testing before any changes would be experienced. The researcher claim:

“Light therapy is an effective treatment of seasonal affective disorder (SAD), when administered daily for at least several weeks. We have previously reported a small improvement in mood in SAD patients following exposure to the first hour of treatment. We now reevaluate retrospectively mood changes during shorter exposures comparing depression ratings at baseline, 20, 40, and 60 minutes of light…The treatment consisted of 10,000 lux of white cool fluorescent light. Depression was measured using the 24-item NIMH scale (24-NIMH)…We conclude that immediate improvement in mood can be detected after the first session of light with exposures as short as 20 minutes, and that 40 minutes of exposure is not less effective than 60 minutes,” the team reports.

Stanley adds that, “Usage times are cumulative, it doesn’t have to be all in one go, and will vary to some extent from person to person and the timing. New research is being carried out all the time, but the key research is that 10,000lux (i.e. visible light received by the user) over 30 minutes treats SAD. Lower lux levels will do the same thing, but over a longer period of time. Furthermore, the melanopsin receptor is more sensitive to bluer wavelengths but as these are less visible they produce lower lux levels. In setting usage times we also rely on photons generated.”

Other researchers recently (July 2011) suggested that bright light therapy (BLT) might also have benefits in chronic depression, post-natal depression, premenstrual depression, bipolar depression and disturbances of the sleep-wake cycle. Although more work needs to be done on those conditions and the effects of BLT. You will probably know that it is typical of the claims of alt med that almost any remedy can treat almost any disorder or condition, which suggests strongly that they’re mostly placebo.

Regarding my skepticism as to whether there is anything special about these therapy lights. Apaper published in September 2011 would suggest that there is no additional benefit or effect of using blue-enriched (sunshine) type fluorescent bulbs rather than conventional bulbs. So, assuming this form of therapy for SAD actually works and that SAD actually exists in the first place and isn’t just yet another invented medical condition for the weary well and the healthy sick hypochondriacs among us, can we assume that a lamp labelled “medical device” is going to be beneficial?

study from 2005 says that “Many reports of the efficacy of light therapy are not based on rigorous study designs.” and that “Adopting standard approaches to light therapy’s specific issues (e.g., defining parameters of active versus placebo conditions) and incorporating rigorous designs (e.g., adequate group sizes, randomized assignment) are necessary to evaluate light therapy for mood disorders.” In other words, how do you exclude the placebo effect and how do you control for things like a “patient” taking a walk on a sunny day?

Stanley does concede that, “We would always say that the best thing for anyone suffering from SAD is to get light from being outside, or seek a winter holiday somewhere bright and sunny. But in the modern world it’s not always practical for people to do this at the right times,” she told me. Hence the market for a BLT.

Research Blogging IconPail G, Huf W, Pjrek E, Winkler D, Willeit M, Praschak-Rieder N, & Kasper S (2011). Bright-light therapy in the treatment of mood disorders. Neuropsychobiology, 64 (3), 152-62 PMID: 21811085

This article has been reproduced from Sciencebase Science News. Copyright David Bradley.

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About David Bradley Science Writer

David Bradley has worked in science communication for more than twenty years. After reading chemistry at university, he worked and travelled in the USA, did a stint in a QA/QC lab and then took on a role as a technical editor for the Royal Society of Chemistry. Then, following an extended trip to Australia, he returned and began contributing as a freelance to the likes of New Scientist and various trade magazines. He has been growing his portfolio and and has constructed the Sciencebase Science News and the Sciencetext technology website. He also runs the SciScoop Science Forum which is open to guest contributors on scientific topics.
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