Is the blue light emitted by computer monitors deleterious for the human eyes?
UV from the Sun (or other strong UV sources, such as germicidal bulbs) is harmful.
Blue light from a computer monitor or cellphone contains insufficient ultraviolet light to harm the eyes, the problem is that blue light causes the suppression of melatonin which affects the onset of sleep, and close up viewing and concentration on digital devices reduces the blink rate by half to one third.
The Canadian Association of Ophthalmology is more cautious in their warnings than their American counterpart, but the difference in the recommendation is that most people over 20 years old should be able to tolerate some blue light that isn't towards the UV end of the spectrum.
Canadian Association of Ophthalmology - "Blue light - Is there a risk of harm?"
UK Association of Opthalmologists - "Our position on the clinical evidence and advice relating to visible blue light"
American Academy of Ophthalmology - "Should You Be Worried About Blue Light?"
American Academy of Ophthalmology - "Should You Use Night Mode to Reduce Blue Light?"
American Academy of Ophthalmology - "Computers, Digital Devices and Eye Strain"
PubSci - "Evening use of light-emitting eReaders negatively affects sleep, circadian timing, and next-morning alertness" (Jan 27 2015), by AM Chang, D Aeschbach, JF Duffy, and CA Czeisler.
Disclaimer: Neither Stack Exchange nor the author offer medical advice.
Some websites offer a stronger viewpoint, opposing blue light.
PreventBlindness.org's About Page discloses that some of the Board of Directors work for eyewear companies, they offer this advice: "Blue light and your eyes" while the website BlueLightExposed.com has no About webpage and offers this advice: "Blue light and macular degeneration".
Wikipedia's webpage on High Energy Visible Light is inconclusive for adults.
There are more unbiased "no" sources than "yes" sources. Blink and take breaks.