THE FACTS

Really? Anahad O’Connor tackles health myths.

In today’s gadget-obsessed world, sleep experts often say that for a better night’s rest, Americans should click the “off” buttons on their smartphones and tablets before tucking in for the night. Electronic devices stimulate brain activity, they say, disrupting your ability to drift off to sleep. But according to the National Sleep Foundation, more than 90 percent of Americans regularly use a computer or electronic device of some kind in the hour before bed.

Increasingly, researchers are finding that artificial light from some devices at night may tinker with brain chemicals that promote sleep. Researchers at Rensselaer Polytechnic Institute showed that exposure to light from computer tablets significantly lowered levels of the hormone melatonin, which regulates our internal clocks and plays a role in the sleep cycle.

In the study, published in the journal Applied Ergonomics, the researchers had volunteers read, play games and watch movies on an iPad, iPad 2 or PC tablet for various amounts of time while measuring the amount of light their eyes received. They found that two hours of exposure to a bright tablet screen at night reduced melatonin levels by about 22 percent.

Studies of college students using computers at night have suggested similar effects on melatonin. And researchers say melatonin suppression may not only cause sleep disturbances, but also raise the risk of obesity, diabetes and other disorders.

To be on the safe side, the authors of the latest study suggest limiting computer use before bed, or at the very least dimming your screen as much as possible.

THE BOTTOM LINE

Artificial light from computer screens at night may reduce melatonin levels.