Wouldn't light therapy glasses like this be harmful for the eyes

[Zelenius]

Wouldn't shining a bright light so close to the eyes be potentially harmful? http://www.gizmag.com/go/1848/

or this http://www.vagabondish.com/led-glasses-promise-to-banish-jet-lag/

While I realize there is a "blue light hazard" when it comes to blue LEDs, wouldn't green LED glasses also be harmful? By "harmful", I mean do they increase the chances of getting macular degeneration or other eye conditions? These glasses would be worn for I'm assuming 30 minutes to an hour every day and usually soon after waking up. I realize this may seem ridiculous, but unfortunately a lot of people are not morning people and are desperate to become more like morning people.

I've used light boxes early in the morning to help reset my clock and deal with insomnia and lack of energy, and it seems to work(this does not mean it will work for everyone, and maybe it is a placebo, but some science supports this - http://www.ncbi.nlm.nih.gov/pubmed/20588229). Unfortunately, light boxes require sitting in front of the box for 30 to 45 minutes every morning. These blue or green LED light glasses allow you to be mobile while undergoing light therapy. While sunlight may be the best light therapy, there is too little of it early in the morning when I have to wake up to be of any use.

Although it doesn't appear these green or blue LED glasses are commercially available yet, are they potentially more dangerous than light boxes? It appears these green or blue LED glasses may be using 1,000 lux of light or less(about an inch away from the eyes or less) but usually more than 200 lux. Light boxes generally use 10,000 lux of white light and require your eyes to be about 12 to 16 inches away to get the therapeutic benefit. It seems about 200 lux of green light may be all that is necessary to get the therapeutic benefit. It may be the minimum.

Blue or green light has a much stronger effect(suppressing melatonin, boosting serotonin) than other wavelengths, so less lux is needed to get the same results as you would get from white light - http://www.pr.com/press-release/241179

I've also found that blocking blue or green light at night(1 to 3 hours before bed) by wearing orange tinted glasses(http://www.independentliving.com/prodinfo.asp?number=541725) helps me go to sleep more earlier and my sleep is deeper(since blue or green light suppresses melatonin, our body's sleep hormone). This is a form of "dark therapy", which may also be helpful for people with bi-polar disorder or depression - http://www.suite101.com/content/dark-therapy-for-bipolar-disorder-a47967.

I used to suffer from chronic insomnia and I never have to take sleeping pills anymore since I started this routine several months ago. In the morning, I do the opposite of dark therapy with these small green LEDs that I look at, but I don't wear them as glasses, but as a visor I made(they strain my eyes a little bit temporarily but my eyesight is fine). Suppressing melatonin in the morning helps me quickly overcome my grogginess and gives me a "boost". I also don't feel depressed in the morning like I did before I started the light therapy. I never drink coffee or caffeinated beverages in the morning or otherwise or take any other drugs(including alcohol) or medication. http://www.sunnexbiotech.com/blue vs green light.html(this site is commercial so its suspect).

It's good news that green light is nearly as effective as blue light when it comes to resetting our circadian rhythms, since blue light may be more hazardous for our eyes.
http://www.mdsupport.org/library/hazard.html

 

[Professor Yaffle]

I don't know, but would be very interested to hear if anyone else does. Sitting in front of a light box in the morning (for SAD) is very inconvenient - would be so much better if I could get on with other stuff while still getting my light. The specs look much better than the light visor I was considering getting: http://www.lumie.com/shop/products/visor-solarmax

 

[Uncayimmy]

My sleep doc tells me that 10,000 lux is the minimum required. The visor PY referenced is 1,000 lux, but they claim the closer distance makes up for it. Thing is, it's hard sometimes to find the lux rating for light boxes with an indication of distance, so 10,000 lux at six inches is nowhere hear 10,000 lux at 24 inches.

 

[Soapy Sam]

Why not sleep with the light on?

 

[Myriad]

Lux, like foot-candles, is a unit of illuminance -- that is, in this case, luminous flux incident on a surface or through a plane in space. In this case the measure of interest is the luminance impinging on the eye. The intensity of the light source is not directly relevant, and is not measured in lux in any case.

So, any manufacturers claim that a visor is "1,000 lux but the closer distance makes up for it" does not quite make sense. This could be honest error, confusion about light measurements which is very common (even if the inventors have a good understanding of the science the marketers may not), or dumbing down of the explanation for marketing purposes.

The illuminance from a light box does vary with distance but as a rule of thumb, does not vary very much provided that the viewer is close to centered and is closer to the box than its width or height (whichever is smaller). (Being close enough to a light box approximates using an infinite light-emitting plane, for which the illuminance would be a constant at any distance.) That's why early research in phototherapy used light boxes instead of smaller closer light sources, it makes it easier to control the illuminance without asking the subject to stare at one spot. In my lab we also used light walls.

What really matters is the light incident on the retina, and that depends on a lot of things. Most people using a light box are probably getting closer to 1,000 lux effectively, even if a photometer positioned at their eye position and aimed directly at the light box would read 10,000 lux, because they're reading or doing similar activity and getting mostly reflected light from the page (with some direct light in their peripheral vision). That seems to be sufficient though.

For comparison, the sky on a very cloudy day sheds about 10,000 lux. On a sunny day, the field of vision while reading outdoors can easily reach 10,000 lux and looking at daylit clear sky (without the sun in the field of vision) can be 100,000 to 1,000,000 lux. Looking at blue sky is apparently harmful long-term, but as far as is known, only because of the UV light. Screening out the UV mitigates all known long-term damage.

Since LEDs do not emit UV and the intensity (of an overcast sky or less) is not enough to do damage even if focused on one point of the retina indefinitely, the danger of harm appears to be negligible.

The potential problem with lights in glasses (which were a pretty obvious idea from day one of phototherapy research) is that with smaller closer light sources, the "dose" varies a lot more depending on exactly how you position the glasses, and whether or not you look toward the lights. You can make the effect more constant by using the small lights to light up the entire lens of the glasses, essentially creating glare on purpose (or having alternating reflective and clear lines on the lenses, or something of that nature) but that will tend to obscure your vision pretty much in proportion to its effectiveness, which may or may not be a problem for any given user. (I'm pretty sure the Re-Time glasses will come with a "do not drive" warning.)

By researching which frequencies are most effective, the Flinders folks gain two advantages that could make the glasses approach more practical: if sensitivity varies with wavelength, less total illuminance is needed if the "right" wavelengths are used. (Regular illuminance measurements weight the spectrum in a way that approximates general visual sensitivity.) And flooding the visual field with monochromatic light (e.g. if the LED's make the lenses of the glasses glow green) would still permit most people to see where they're going in other colors.

A caveat though: doing this kind of research is tricky. It's hard to control all the variables in human trials, and it is difficult to measure changes in circadian rhythms accurately. The easier measures (such as alertness, and body temperature under active conditions) are inaccurate, and the accurate measures (such as timing of hormone releases and core body temperature under "constant routine" conditions) are difficult and expensive to perform. Replication is vital for circadian studies, even more so than in other specialties.

It's been pretty well established in animal studies that the circadian effects of light do vary with wavelength, and that the shorter wavelengths have more effect. That's why zoos display nocturnal animals under red lights in the daytime so that visitors can see them active; the red does not prevent the animals from staying on an artificially inverted schedule. This was also suspected to be the case in humans, to the point where some circadian studies have even used low red lighting for convenience during "dark" periods without too much concern that that would skew the results.

The "Sleep Researcher" mentioned in the promo appears to be Dr. Leon Lack of Flinders University School of Psychology, and he appears to be the real deal. Here's his page about the light therapy glasses project.

I'd say the glasses would be likely to work (though not for everyone), and would therefore be worth a try, for anyone already using a light box or for anyone for whom the phototherapy is non-critical (e.g. reducing occasional ordinary jet lag). I'd still recommend a light box for clinical applications, such as treatment of SAD or sleep phase syndromes, until the glasses are well tested in practice.

Respectfully,
Myriad

 

[casebro]

Pupils control the light entering the eye, so the retina is exposed to a constant amount. I would think the point would be enough light to cause the pupils to constrict? Look in a mirror while in the light, check the size of your pupils?

So what is the biology here? Constricted pupil muscles give off a chemical messenger, or is it strictly psychological?

And didn't I hear that the most photo receptive place re: body clock is the back of the knees. So wear some LEDs inside of a knee support?

 

[Professor Yaffle]

And didn't I hear that the most photo receptive place re: body clock is the back of the knees. So wear some LEDs inside of a knee support?

Nope:
http://preventdisease.com/news/articles/light_knee_bodyclock.shtml

 

[Soapy Sam]

They'd make good foot warmers...