One area where this can matter more than standard lighting is light therapy devices. I have a circadian sleep disorder and for those light therapy is one of th

One area where this can matter more than standard lighting is light therapy devices. I have a circadian sleep disorder and for those light therapy is one of the few medically recommended treatments (it is also recommended in the winter for seasonal affective disorder). There are two basic types of light therapy devices, a bright light that you set on the table nearby and a less bright light in a visor that you put near your eyes. I think LEDs are universal in the visor style ones and quite common in the table ones. The blue spectrum is more effective than other wavelengths so they are frequently focused on the blue spectrum although some of the table ones are white light. They are only supposed to be used for a half hour or hour at most. I just tried for a couple of weeks a visor style light that is just over 500 lux at 500nm dominant wavelength (blue-green; it looks green and is a longer wavelength than most such devices). While it didn't seem super bright, it did seem fairly bright and actually caused me mild pain, similar to what bright light occasionally causes. The lower 315 lux level did the same at first. I started with that a few days and it seemed like my eyes adapted quite a bit so I moved to the higher level. I got spooked after noticing the pain later in the day one day after using the visor on high in the morning, so I haven't tried the lower level again to see if that still causes pain. The manufacturer said that in studies about 3% of people report that problem. Anyway, it seems to me that my use of the visor might be similar to the lighting in this study. I haven't noticed this issue with other artificial lighting, although I haven't been around LEDs that much that I know of, mostly compact flourescents. The closest is a led light alarm clock that I have stared at at close range for a while and is listed at 300 lux, although I'm not sure if that is what I am getting even a few inches away. The visor light does have a 50-166 hz pulse so that could be related; I'm not sure about the light alarm, but I never noticed that flicker the way the visor does. Anway, 500 lux at eye level at least can be quite a bit different than normal lighting.