Next generation blue light could potentially promote or hinder sleep on command

Blue light from LED lamps and consumer electronics can interfere with the production of the natural sleep hormone melatonin, which can disrupt sleep. Tinted glasses or displays in night mode can mask, but not remove, a portion of the disruptive wavelengths. However, researchers have designed more “human-centric” LEDs that could potentially enhance drowsiness or alertness on command.

Humans have evolved over millennia to be active during the day and to rest at night; we’ve depended on the sun to regulate our sleep/wake cycle. But many people today spend the majority of their time indoors, shielded from the sun, so it’s harder for them to maintain that optimal 24-hour circadian rhythm Exposure to artificial light can worsen this problem because it can decrease the secretion of melatonin.

Blue light ranges in wavelength from 380 to 500 nanometers (nm), but not all blue light is created equal. The wavelengths that suppress melatonin production—and cause wakefulness—are in the range of 460 to 500 nm. So, researchers have designed two LEDs that emit different wavelengths of blue light. One LED, intended for daytime use, restricts its blue emissions to wavelengths close to 475 nm. The other LED, for evening use, emits blue wavelengths near 450 nm, outside the range that disturbs sleep.