In my last post I discussed that awareness of blue light is growing among our patients.
Mainstream media stories are taking on the subject of blue light and its health consequences head on. I have seen stories in the lay press regarding blue light and age-related macular degeneration, blue light and visual performance and, just recently, a piece on blue light and sleep disturbance. On April 9, ABC News’ Good Morning America ran a piece on wearing “orange-tinted glasses” before bed when looking at electronic devices. While overall the piece was well done, there was something that was unsettling to me.
The story centered on a recently published study in the Journal of Adolescent Health. In the study, 13 15- to 17-year-old healthy boys were followed for a 2-week period. The authors wanted to investigate whether wearing blue light-blocking glasses, particularly lenses that block blue light within the circadian action spectra (460 nm to 480 nm), would have an effect on sleep-initiating mechanisms.
Subjects were exposed to LED screens while either wearing clear lenses or blue-blocking lenses. Measures of melatonin secretion, vigilant attention/sleepiness and sleep were measured. Results showed significantly more melatonin secreted for the blue light-blocking lenses group along with feeling significantly sleepier at bedtime. Sleep quality between the two groups was not statistically different, although the authors acknowledge that the 1-week trial may not have been long enough to alter circadian rhythm.
An important point I picked up on in reading this study is that the authors found that blue-blocking lenses only modified vigilant attention and subjective sleepiness in the evening before sleep but not the morning after. In other words, when the investigators had subjects wear blue-blocking lenses the next morning vs. wearing clear lenses, there was no measured difference in sleepiness or alertness. I find this striking because, as of late, I have seen promulgated that wearing blue-filtering lenses throughout the day will cause sleepiness and decreased alertness.