bluelight

Blue light refers to part of the visible light spectrum with wavelengths approximately 450 to 495 nanometers. It is emitted by the sun and by many artificial sources, including light-emitting diodes (LEDs), compact fluorescent lamps, and digital screens such as smartphones, tablets, computer monitors, televisions, and some indoor lighting. Because it is high-energy visible light, blue light has a greater potential to affect physiological processes than longer-wavelength light.

In the human eye, blue light is detected not only by the cones responsible for color vision but also by intrinsically photosensitive retinal ganglion cells containing melanopsin, which help regulate circadian rhythms, pupil size, and alertness.

Exposure to blue light, particularly in the evening or at night, can suppress melatonin production, delay sleep onset, and shift circadian timing, potentially reducing sleep quality and daytime alertness. The magnitude of these effects depends on light intensity, exposure duration, and timing relative to an individual’s circadian cycle.

The safety of blue light for the retina remains a subject of research. Most everyday exposure from screens is far below levels associated with acute retinal injury, and there is no consistent evidence that typical blue light from consumer devices causes macular degeneration. Some occupational or accidental exposures to very intense blue light may pose risks.

Mitigation strategies include reducing evening blue light by using warm color settings or blue light filters, wearing blue-blocking glasses, adjusting room lighting to lower intensity and glare, and taking breaks to reduce eye strain. Ongoing research continues to clarify long-term effects and optimal exposure guidelines.