Bright device screens can inhibit sleep

Exposure to devices with self-luminous "backlit" screens causes melatonin suppression that can lead to sleep problems, especially in teens, U.S. scientists say. "Our study shows that a two-hour exposure to light from self-luminous electronic displays can suppress melatonin by about 22 percent," Mariana Figueiro of Rensselaer Polytechnic Institute in Troy, N.Y., said. "Stimulating the human circadian system to this level may affect sleep in those using the devices prior to bedtime." Melatonin, a hormone produced by the pineal gland at night and under conditions of darkness, is a "timing messenger" signaling nighttime information throughout the body, the researchers said. "Technology developments have led to bigger and brighter televisions, computer screens, and cell phones" Rensselaer researcher Brittany Wood said in a Rennsselaer release Monday. "To produce white light, these electronic devices must emit light at short wavelengths, which makes them potential sources for suppressing or delaying the onset of melatonin in the evening, reducing sleep duration and disrupting sleep. "This is particularly worrisome in populations such as young adults and adolescents, who already tend to be night owls."