EFFECT OF BLUE BLOCKING LENSES ON MELATONIN LEVELS IN HEALTHY MALES EXPOSED TO BLUE LIGHT IN THE EVENING
Charles J. Woody, Argyris S. Zachariou, Christopher C. Woody, Danielle C. Marino, Sandra L. Weber
Recent studies have shown that 90% of people in the US view an electronic device prior to bedtime. This has been shown to cause sleep disruption via inhibition of melatonin production. This effect is not seen when reading a printed book. Commercially available lenses purportedly designed to block this blue light are now available. However, there are currently no evidence-based studies that support these claims. This pilot study is designed to test the ability of the best commercially available blue-blocking lens, BluTech, on melatonin levels in healthy adult males exposed to blue light when viewing an electronic device (iPad) prior to bedtime.
Ten healthy males, ages 24–28 years, participated in the study. All had 20/20 best-corrected vision, normal color vision, and no known ocular pathology. Each subject was asked to go to bed between 11 pm and midnight seven days prior to the study. On the evening of the study, each subject reported to the lab at 6 pm to have an IV catheter placed to allow blood sampling during the study. At 7 pm each subject was placed in a private room with internal lighting set at 10 lux. A blood sample was obtained (time 0) and the subject began reading on an iPad. The study was conducted over two consecutive nights. On night one half the subjects wore glasses containing BluTech (experimental) lenses and the other half wore glasses containing clear (control) lenses. Blood samples were collected every hour for three hours. The procedure was repeated the next night with each subject wearing the alternate pair of glasses.
Half of the subjects had significantly higher melatonin levels at hour 3 with the blue-blocking lenses than with the clear lenses. Two of the subjects had greater melatonin levels at hour 3 when wearing clear lenses and two subjects had similar levels with both the clear and blue-blocking lenses. One subject had a markedly elevated level of melatonin at time zero on the day he wore clear lenses. In this individual, melatonin levels decreased during the evening he wore clear lenses but increased during the evening he wore the blue-blocking lenses.
We noted variation in the subjects tested. While most had very low melatonin levels at the start of the evening there were exceptions. Most of our subjects had rising melatonin levels throughout the evening that was greater with the blue-blocking lenses, but again, there was some variation. We need to further examine this process to identify the confounding variables involved.
The data from this pilot study suggest that blue-blocking lenses may be useful in reducing the suppression of melatonin during exposure to blue light in the evening.