The blue light emitted by our electronic devices, which can keep us from sleeping when exposure happens before bedtime, might someday be tunable to promote or hinder sleep on command, researchers say.
Blue light from LEDs in lamps, televisions, mobile phones and other devices disrupts production of the natural sleep-promoting hormone melatonin, making it harder to maintain the sleep/wake patterns necessary for an optimal 24-hour circadian rhythm.
“But not all blue light is created equal,” the South Korean researchers said in a statement.
Blue light wavelengths that suppress melatonin production and cause wakefulness are in the range of 460 to 500 nanometers (nm), they noted in a report published in ACS Omega.
The researchers, with funding from Samsung Electronics, built LED bulbs that can emit wavelengths close to 475 nm, for use during the day, or near 450 nm (outside the range that disturbs sleep) for use in the evening.
To the naked eye, the bulbs appeared to emit plain white light regardless of the blue-light wavelength.
For their study, 22 male volunteers spent three days inside windowless furnished rooms, with a computer controlling the type of LED that was turned on or off.
Saliva samples from the volunteers showed that use of the new LEDs increased nighttime melatonin levels by 12.2% and reduced daytime melatonin by 21.9% compared to use of conventional LED bulbs.
Eventually, consumers could have access to LED lamps and electronic displays that help to improve daytime vitality and work efficiency as well as nighttime relaxation and sleep quality, the researchers said.
“The Human-Centric LED, which is expected to improve the circadian rhythm by controlling the wavelength band of light directly related to melatonin, will be (useful) for maintaining a healthy circadian rhythm in modern life, where people spend more time indoors,” they concluded.
This newsletter was edited by Bill Berkrot.
