on 2017-02-20 Highly insufficient for SAD sufferers / light therapy
Warning to SAD sufferers: This lamp produces BY FAR insufficient light.
Using my light meter
, and a tape measure, I measured:
10,000 lux, yes, BUT ONLY at 3 inches from the surface of the lamp.
Sitting at my desk, using the measuring tape from my eye to where this lamp might sit to my left or right, or over/behind my computer monitor, I measured 24 inches to be about how far away it would sit.
Again, using the light meter, at 24 inches, this lamp produced only about 400 lux.
See Wikipedia for a description of "lux": Lux is a measure of the number of lumens of light received per square meter. (1 lux = 1 square meter of area is getting 1 lumen)
But at how far away, right? I mean, everyone knows that light is less bright the further away from it you get. Therefore, a lux measurement should ALWAYS ALWAYS ALWAYS be accompanied by a DISTANCE. Example: "45 lux AT 3 FEET AWAY".
Flashlight and light bulb manufacturers get around this problem by simply quoting lumens (which we assume they measure RIGHT AT THE LIGHT BULB). But to know how many *lux* you're getting at your eyeball (which should dang well NOT be at the surface of a light bulb), you can't quote lumens. You have to quote lux PLUS the distance you'd be away from it.
Okay, so if we're agreed that lux needs distance always quoted with it:
Now let's look at the 2DayDeliver description for this product. It only says, "10,000 lux". But where's the distance? Missing.
How about the box? The box says, "Light intensity of natural spectrum daylight of approx. 10,000 lux". Super. Still missing the distance, right?
How about the manual? I have scanned in a page of the relevant sections of the manual:
Section 9. Specifications:
Light intensity approx. 10,000 lux. (Still missing the distance, right?)
Section 6. To Use
8 inches for 1/2 hour per day or 16-24 inches for 2 hours per day, etc.
This table is just plain wrong. At least with the unit I got, and the light meter I used.
Even at 8 inches (and no way could I stand having this thing only 8 inches from my face), I still measured only 2,250 lux. How long would that take me to get the therapy? I estimate:
(10,000 / 2,250) * 30mins = 133mins = 2 hrs 13 mins .. NOT 1/2 hour!
Even their suggestion that one could use it for 2 hours at 16-24 is inaccurate, since that's a huge range, and lux will definitely be much lower at 24 inches than at 16.
Again, for the unit I purchased from 2DayDeliver, I only got the 10,000 lux === AT 3 INCHES ==.
As most of you may know, to get true therapy, researchers advise at least 10,000 lux (at your eyeball) for 30 minutes, daily. (Or 5,000 lux for an hour, or 2,500 lux for 2 hours.)
How low could we go on the lux, though, just increasing the time?
Well, it turns out that researchers also state that the MINIMUM lux needs to be 2,500 for it to begin to take effect. THEREFORE, we can't just work with a weak light (under 2,500 lux at the distance we have it) and add more time. It won't work.
So, if 400 lux WERE above the minimum therapeutic level, and I placed this Beurer unit a reasonable 24 inches away on my desk or over my monitor, how long would it take me to get the same therapy from this weaker lamp that I would for 30 minutes using a lamp which was giving me a true 10,000 lux at my eye?
(10,000 / 400) * 30mins = 750mins = 12.5hrs
Which, of course, is ridiculous.
BUT!!!!! Because of the minimum lux of 2,500 for the 'timer' to even start on therapy, it means that placing this at a reasonable distance of 24" on your desk will give NO therapeutic results -- at least for most people -- according to the researchers, at least.
Maybe someone gets some therapy from this -- but, if what the researchers say about minimum lux of 2,500 *for most people* is true, then either the people reporting that they like this light are among the few who can get therapy from only low levels of light, OR there is a placebo effect going on for them.
Conversely, even if someone might argue, "Yeah, but I would have this lamp closer than you would," would they *really*? I would challenge them to measure their desk and how they sit when working. I'll bet 24" is *at least* the distance they would have it at.
And even if they would have it closer, would they really have it only 3 inches away from their eyes for 30 minutes?
Again, to get the minimum lux of 2,500, you'd have to be CLOSER than the 8 inches i measured 2,2500 lux at. Say, 7 inches. Are you REALLY going to hold or position this sucker 7" away from your face for 2 whole hours?
It is HUGELY IMPORTANT for any SAD sufferers to invest in a lux meter. As you see from following the link to mine, they are inexpensive here on 2DayDeliver -- and there are several other models equally good or better. So we've no reason not to get one, and get confirmation from any device (or even from walking outside) how much light we are truly getting.
One more minor point: The little green plastic snap-in stand that props up this lamp from the back: It fell out by itself several times while I was measuring the unit, dropping the lamp onto the table. I did not get confidence in its quality from this. Yet a minor issue compared to the lux.
Hope this helps someone. If I'm wrong on any of this stuff, please comment, and I'll correct/fix it.