A reader asks:

Is there a difference in the therapy effect in the use of LED vs CFL bulbs?


LED light boxes have begun to appear on the market, but as of 2022 they are still too small to project a wide enough spread of light at the eyes for consistent dosing with minimal aversive glare.  While the labelling of color temperature (in degrees Kelvin) for fluorescent lamps and LEDs might appear very similar (for example, both at 4000 °K), the underlying distribution of light wavelengths can look very different. Both types of lamp show spikes in activity at certain wavelengths, but they do not line up. As of now, there have been no clinical trials comparing the antidepressant effect of light therapy from the two light box types. Even so, most experts would agree that LED technology holds great promise. Before investing in it, though, wait for larger screens to get to market. It will surely take longer for new clinical trials to use LED light boxes, and even then we will probably never see the two bulb types compared in the same trial. Before considering an LED lightbox, you should not hesitate to query the manufacturer for results that support the use of their particular brand. Beware of seemingly exaggerated claims!