Blue Light Science
What blue light is
Blue light is part of the visible light spectrum. It is present in natural daylight and is also emitted by screens and many artificial light sources. The amount and spectral distribution depend on the source, brightness, distance and time of exposure.
What NoBlue measures
NoBlue separates measurable optical performance from claims about health outcomes. The Day and Evening / Orange lens systems have been evaluated using spectral transmission measurements at Lodz University of Technology, Institute of Electrical Power Engineering.
The current NoBlue evidence block uses the measured wavelength range 400–500 nm. The current Day and Evening filtering values are maintained centrally and shown on the NoBlue Test Results page together with source details.
Optical measurements are not clinical outcomes
A lens can be measured accurately for spectral transmission, but that does not by itself prove a particular effect on eye strain, sleep or eye health. A 2023 Cochrane systematic review of 17 randomised trials found that blue-light filtering spectacle lenses may not reduce short-term computer-related eye strain compared with non-blue-light filtering lenses, while evidence for sleep-related outcomes remained uncertain.
The American Academy of Ophthalmology also notes that digital eye strain is strongly related to screen-use behaviour, including reduced blinking, and does not recommend blue-light filtering glasses on the basis of claims that ordinary screen light damages the eyes.
What this means when choosing a NoBlue product
Use measurable differences first: lens transmission, visible tint, intended time of day and product format. Daytime glasses use a lighter visible tint for daytime screen routines. Evening glasses use visibly orange lenses for screens and artificial light after dark.
For the complete product map, see the Blue Light Guide. For current lens measurements, use NoBlue Test Results.
Independent research references
Cochrane Review: Blue-light filtering spectacle lenses
American Academy of Ophthalmology: Blue light and computer glasses