Aug. 31, 2012 — Is setting down your iPad the last thing you do before bed? New research shows that all of those nighttime hours spent with your tablet can wreak havoc on your sleep.

The bright light emitted from these tablets can suppress melatonin. That’s a hormone that helps control sleep and wake cycles, called circadian rhythms.  

The researchers only looked at the iPad, iPad 2, and a tablet known as the Asus. Using these tablets for two hours on their brightest settings suppressed melatonin by about 22%. The findings appear in the journal Applied Ergonomics.

“If they are bright and they are big and are close to your eyes, they have more potential to disrupt your melatonin than the TV, which is usually farther way,” says researcher Mariana Figueroa. She is an associate professor at Rensselaer Polytechnic Institute in Troy, N.Y.

iPhones and other small gadgets may not affect circadian rhythms. “Smaller devices emit less light,” she says. But even if these devices aren’t zapping the body’s melatonin supply, they may still be disrupting sleep by delaying your bedtime, she says.

Not ready to give up your tablet before bedtime? Follow these four tips to make sure you use them in a way that does not leave you tired all day long.

1. Invest in a Filter

Inexpensive filters can help turn down the glare and block out melatonin-zapping blue light, says Figueiro. Look for one that cuts off wavelengths below 520 nanometers (nm). “You can still see the screen and do your task, although the color is compromised.”

2. Dim the Lights

In the study, participants used the tablets at full brightness, but you don’t have to, she says.  “Use the automatic dimmer function at night,” she says. Turn off the lights in your bedroom as well.

3. Distance Yourself From Your Tablet

“Proximity is an issue,” says Michael Breus, PhD. “When we use these devices, we hold them closer to our face than we would a TV or a computer.”

4. Impose an E-Curfew

“These devices are faking out our body and saying it’s morning when it’s night,” Breus says. This disruption in circadian rhythms can affect learning among school-aged children. “Impose an electronic curfew,” he suggests.