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Is That Light from Your E-reading Keeping You Awake? Yes!

By Publishing Perspectives

The study doesn't say if LED lights, like those used on the new Kindle Paperwhite, have the same effect.

Science Daily reported that a new study from the Lighting Research Center (LRC) at Rensselaer Polytechnic University, published in the journal Applied Ergonomics, shows that a two-hour exposure to luminous back-lit displays — like e-readers — suppresses melatonin, which could then affect sleep by disturbing the body’s natural circadian rhythm.

Researchers, led by Mariana Figueiro, associate professor at Rensselaer and director of the LRC’s Light and Health Program, examined the effect of these devices on melatonin in 13 people. All of the study participants read, played games, and watched movies on a tablet. “Our study shows that a two-hour exposure to light from self-luminous electronic displays can suppress melatonin by about 22 percent. Stimulating the human circadian system to this level may affect sleep in those using the devices prior to bedtime,” said Figueiro.

(Science Daily defined melatonin as a hormone produced by the pineal gland at night, as well as under conditions of darkness in both diurnal and nocturnal species. It is considered a “timing messenger,” signaling nighttime information throughout the body. Exposure to light at night, especially short-wavelength light, can slow or even stop nocturnal melatonin production. The suppression of melatonin by light at night reading that results in circadian disruption has been implicated in sleep disturbances, an increased risk for diabetes and obesity, as well as increased risk for more serious diseases, such as breast cancer, if circadian disruption occurs for many consecutive years, such as in nightshirt workers.)

LRC Research Specialist Brittany Wood, one of co-authors of the study, pointed out that “Technology developments have led to bigger and brighter televisions, computer screens, and cell phones. 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.”

Figueiro added that until manufacturers develop more “circadian-friendly” electronic devices that can increase or decrease light exposure based on time of day that “We recommend dimming these devices at night as much as possible in order to minimize melatonin suppression, and limiting the amount of time spent using these devices prior to bedtime.”

Our solution: F.lux, which is a fantastic program for the Mac that changes the color temperature of your computer monitor to one that doesn’t suppress melatonin (or so they say). And there’s no word yet on the LED powered “glow” that has been incorporated into several new readers, such as the Nook Touch with Glowlight, the Kobo Glo and the Kindle Paperwhite.

Or…one could simply curl up in bed with a good old-fashioned book instead.

Read the complete report here.

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