Exposure to back-lit electronic devices, such as tablets, before bedtime could lead to sleeplessness, suggests a new study.

A two-hour exposure to self-luminous displays may cause melatonin suppression strong enough to affect sleep by disturbing the body's natural circadian rhythm, a small new study in the journal Applied Ergonomics suggests.

“Our study shows that a two-hour exposure to light from self-luminous electronic displays can suppress melatonin by about 22%. Stimulating the human circadian system to this level may affect sleep in those using the devices prior to bedtime,” said study author Mariana Figueiro, in a statement.

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  • George Clooney

    The Oscar-winning actor told <em>The Hollywood Reporter</em> that he has <a href="http://www.hollywoodreporter.com/news/george-clooney-oscars-brad-pitt-stacy-keibler-descendants-290691" target="_hplink">trouble falling asleep without the TV on</a>. "I'm able to numb out," he said about the blue glow. While many claim falling asleep to the TV helps them nod off, it can actually disrupt the sleep cycle. Your brain will still <a href="http://www.huffingtonpost.com/2012/02/14/sleep-compatibility-_n_1274860.html" target="_hplink">listen in on subtle changes in volume</a>, even if you're asleep, Phillip Gehrman, Ph.D., CBSM, clinical director of the Behavioral Sleep Medicine Program at the University of Pennsylvania told The Huffington Post. That could account for Clooney's trouble <em>staying</em> asleep. "Without question, I wake every night five times," he said.

  • Rihanna

    Amid swirling rumors of a reunion with ex-boyfriend Chris Brown, the "We Found Love" singer has taken to Twitter on multiple occasions, sending messages that she's having trouble sleeping. In January, <a href="http://www.capitalfm.com/artists/rihanna/news/chris-brown-sleep/" target="_hplink">after completing a world tour</a> in 2011, she tweeted <a href="https://twitter.com/#!/rihanna/status/154801966898364417" target="_hplink">"Suddenly all the silence is being drowned by my thoughts! No sleep"</a> and in February started adding <a href="https://twitter.com/#!/rihanna/status/171119260427485184" target="_hplink">#GOtoSLEEPRobyn</a> to some of her tweets. Surfing the web, checking email or tweeting too close to bedtime, however, can send signals to your brain that <a href="http://www.huffingtonpost.com/gretchen-rubin/bedtime-tips_b_1280228.html" target="_hplink">disrupt the natural bedtime process</a> and make it harder to drift off.

  • Lady Gaga

    There's no denying the pop star is, at the very least, extremely passionate about what she does. But all that drive has her tossing and turning at night, she told the UK's <em>OK! Magazine</em> in 2010. "My passion is so strong I can't sleep -- I <a href="http://www.ok.co.uk/celebnews/view/20373/Lady-Gaga-I-haven-t-slept-in-three-days/" target="_hplink">haven't slept for three days</a>," she said. "I lie in bed and try to pray and breathe. I have a very overactive mind. " Whether or not she really meant she'd been awake for a solid 72 hours or simply didn't sleep <em>well</em> three nights in a row, <a href="http://www.huffingtonpost.com/2012/02/21/sleep-deprivation_n_1290067.html" target="_hplink">sleep deprivation</a> has real consequences. Among the most frightening is a <a href="http://www.huffingtonpost.com/2011/06/17/sleep-deprivation-dangers_n_878743.html" target="_hplink">decrease in reaction time</a>, which, if you're driving, could prove deadly.

  • Shaquille O'Neal

    The basketball giant sat down with Dr. Charles Czeisler, director of the division of sleep medicine at Harvard Medical School, who approached him to be a part of a sleep study. O'Neal's girlfriend had been insisting he get <a href="http://healthysleep.med.harvard.edu/sleep-apnea" target="_hplink">tested for sleep apnea</a>, after noticing him snoring and then seemingly stop breathing during the night, she said. Sleep apnea, which occurs when someone temporarily stops breathing during sleep, is more common in people who are overweight and/or have thick necks. At 7'1" and an <a href="http://www.boston.com/lifestyle/health/blog/dailydose/2011/05/shaq_discusses.html" target="_hplink">estimated 325 pounds</a>, Shaq certainly fits the bill, points out Boston.com. Sleep apnea is often treated with a ventilation therapy known as <a href="http://www.huffingtonpost.com/2012/01/10/sleep-apnea-disorder-tips_n_1196851.html" target="_hplink">CPAP</a> (continuous positive airway pressure) that requires the snorer to sleep with a Darth Vader-esque mask. Shaq said he planned to wear his every night -- and joked he might wear it out on the town, too.

  • Kevin Jonas

    Nearly <a href="http://www.huffingtonpost.com/2012/02/14/sleep-compatibility-_n_1274860.html" target="_hplink">a third of American adults snore</a>, which can cause serious problems in a relationship if a light-sleeping partner is constantly woken up. Reportedly among the ranks of <a href="http://www.huffingtonpost.com/2012/02/14/sleep-compatibility-_n_1274860.html" target="_hplink">mismatched sleep partners</a> are musician and actor Kevin Jonas and his wife Danielle, according to <em>In Touch Weekly</em>. A friend of the couple said "Kevin and Danielle had never spent a night together until their wedding night, so she had no clue that he snores so loudly. She loves her husband, but now she <a href="http://www.intouchweekly.com/2010/05/jonas_marriage_drama.php" target="_hplink">sleeps in a guest room</a> when he gets too noisy." Snorers can try sleeping on their side instead of their back, using a pillow or a tennis ball sewn into a T-shirt to stop them from rolling over.

  • David Ortiz

    During a 2009 slump, Ortiz, designated hitter for the Boston Red Sox, had only two homeruns and 22 RBI. In his previous years with the Red Sox, he had averaged 39 homers and 122 RBI. The slip in his performance affected more than just his stats. "My body is resting every night, but my mind is spinning with all of this [stuff]," he told <em>USA Today</em>. "<a href="http://www.usatoday.com/sports/baseball/al/redsox/2009-06-07-ortiz-bay-cover_N.htm" target="_hplink">It's hard to sleep</a>."

  • Sandra Bullock

    After adopting her son, Louis, the Oscar-winning actress drastically cut down on sleep. She told the UK's <em>Now Magazine</em> she was surviving on just <a href="http://www.nowmagazine.co.uk/celebrity-news/453558/sandra-bullock-i-m-only-getting-3-hours-sleep/1" target="_hplink">three hours a night</a>, but that it wasn't difficult. "I don't want anyone else to have the pleasure of changing [his] diapers but me," she said. "There is nothing hard about loving Louis." That may be true, but Bullock's extreme sleep deprivation could actually <em>hurt</em> little Louis. Severely skimping on sleep has been linked with a greater risk of <a href="http://www.usatoday.com/news/health/2010-01-14-Sleep14_ST_N.htm" target="_hplink">making serious mistakes</a> in doctors, police officers, truckers and others in positions that require long hours. To ensure you're giving little ones the best care, you need to take care of yourself first.

  • The New York Knicks

    New York Knicks small forward Steve Novak told radio host Mike Francesca that the team is <a href="http://newyork.cbslocal.com/audio/19-02-mike-francesa/steve-novak-with-mike-francesa/" target="_hplink">having trouble sleeping</a> in the wake of "Linsanity". "We actually had a meeting today before practice with a doctor to talk about ways to help you sleep at night," Novak said. "It's like the energy when we leave -- it's like it's midnight, and you go home and <a href="http://www.huffingtonpost.com/2012/03/03/the-knicks-sleep_n_1318446.html" target="_hplink">we can't sleep</a>." It's no surprise that all the adrenaline is keeping them awake, but taking some time to <a href="http://www.huffingtonpost.com/2012/03/03/the-knicks-sleep_n_1318446.html" target="_hplink">unwind after the game</a> -- with sleep aids like relaxation CDs or progressive muscle relaxation -- can help, Jerrold Kram, M.D., medical director of the California Center for Sleep Disorders and a member of the board of directors for the National Sleep Foundation told The Huffington Post.

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Melatonin is a hormone produced by the body when it’s dark to encourage sleepiness.

Suppression of melatonin by light has been implicated in sleep disturbances, increased risk for diabetes and obesity, as well as increased risk for more serious diseases, such as breast cancer.

Could this bed 'rock' you to sleep?

Participants in the study used self-luminous tablets to read, play games, and watch movies. While one-hour exposure to tablets caused little affect, after two hours, melatonin levels dropped significantly.

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Figueiro said in a statement: “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.”