Blue light filters don’t work
Hacker News
February 20, 2026
AI-Generated Deep Dive Summary
Getting better sleep is a common goal, but the effectiveness of blue light filters in achieving this has been widely questioned by experts. As a visual neuroscientist explains, these filters are not as impactful as many believe. The real key to regulating sleep lies in controlling total luminance, or overall brightness, rather than just filtering out specific wavelengths of light.
The human body’s circadian rhythm is influenced by the suprachiasmatic nucleus (SCN), a tiny group of cells in the brain that respond to light signals transmitted through intrinsically photosensitive retinal ganglion cells (ipRGCs). These cells detect light using melanopsin, which has a sensitivity peak in the cyan range—not just blue. This means that simply blocking blue light doesn’t significantly reduce the overall impact on sleep cycles.
Rather than relying on color-shifting software or filters like f.lux or Night Shift, a more effective approach involves minimizing total luminance at night and using red-tinted glasses if screen use is unavoidable. These methods are far better at suppressing melatonin production and aligning circadian rhythms compared to blue light filtering alone.
From a tech and startup perspective, this shift in understanding opens new possibilities for innovations beyond traditional blue light solutions. Products that focus on reducing overall brightness or incorporating advanced red-tinted technologies could offer more effective sleep and jet lag management options for consumers.
Verticals
techstartups
Originally published on Hacker News on 2/20/2026