Abstract

Blue light blocking glasses are being actively marketed as a non-pharmacological approach to lessen the negative impact of the exposure to artificial light and screen-based devices in the evening. Their mechanism is grounded on the sensitivity of melanopsin-containing intrinsically photosensitive retinal ganglion cells to short wavelength light which alters circadian timing, melatonin release, alertness, and associated neuroendocrine pathways. This narrative review assesses the implications of blue light blocking glasses on sleep, circadian regulation, visual performance, digital eye strain, neuroendocrine and neurophysiological and relates them to the bigger picture of current artificial light exposure. The evidence provided indicates that these glasses offer the best biological justification to the evening wear as far as sleep and circadian physiology are concerned. According to several studies exposure to short-wavelength light before bedtime can be reduced to mitigate the suppressive effect of melatonin, facilitate circadian synchrony, and have a modest effect on sleep initiation or sleep quality, especially in persons with insomnia or delayed sleep phase disorder. Conversely, there is inconsistent evidence of digital eye strain and visual performance. Other studies have found less subjective eye fatigue, and higher visual comfort, but randomized controlled trials have found no, or minimal, clinically meaningful advantage relative to conventional lenses. There is also preliminary evidence that it may have neuroendocrine and neurophysiological consequences, such as changes in melatonin responses and brainwave activity, although these effects are not well-studied. The concept of blue light-blocking glasses can be seen as a highly feasible addition to a broader approach to light management, rather than a complete solution to sleep or visual and cognitive well-being.