Tablet Light May Affect Sleep By Suppressing Melatonin

Your new tablet may be convenient for reading on the go, but it may not be so good for your sleep.

Two hours of exposure to devices that have luminous back-lit displays -- like tablets -- suppresses melatonin, which could then affect sleep by disturbing the body's natural circadian rhythm, a small new study in the journal Applied Ergonomics suggests.

Researchers from the Lighting Research Center at Rensselaer Polytechnic Institute examined these devices' effects on melatonin in 13 people. They had all the study participants play and watch movies on a tablet; some of them wore special goggles that affected the body's melatonin production based on the light from the screens.

The researchers found "that a two-hour exposure to light from self-luminous electronic displays can suppress melatonin by about 22 percent," study researcher Mariana Figueiro, an associate professor at Rensselaer Polytechnic Institute and the director of the Light and Health Program, said in a statement. "Stimulating the human circadian system to this level may affect sleep in those using the devices prior to bedtime."

The researchers noted that some tablets emit different degrees of light than others, so it's not possible to make a broad generalization that all tablets at all light settings produce this effect to this extent.

But "we recommended 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," Figueiro said in the statement.

For more surprising things keeping you from good sleep, check out this infographic from the National Sleep Foundation:

Clarification: A previous version of this article mentioned ereaders and tablets interchangeably, although the study only looked at lighting from tablets. It has been amended to only refer to tablets.