Who's sleeping, who's not?

Celebrities lead fabulous and often hectic lives - jetting across the country on a whim, partying at late-night hot spots, following rigorous touring or filming schedules - so it's no surprise that sleep may not always be a number-one priority. Insomnia and prescription medication have even been implicated in some high-profile celebrity deaths, raising the issue of how dangerous sleep problems can be if not treated responsibly.

What other members of the glitterati have spent their nights tossing and turning? With the help of our friends at Health.com, we've compiled a list of famous men and women, past and present, who have spoken out about or become known for their unique sleep issues. Keep clicking to see who gets too much and not enough - and what you can learn from each of them.

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Renee Zellweger

As a result of her busy schedule, Zellweger, of Bridget Jones and Chicago fame, doesn't always have time to sleep. "Your body doesn't quite register...that it's time to sleep," she told W magazine in 2005, recalling a 10-day, 10-country promotional tour for Bridget Jones: The Edge of Reason. "But you don't fight it, and you don't ask questions after a while. You just kind of let it happen to you."

Overworked people, celebrities or not, can have trouble winding down before bedtime and might lie awake worrying about their commitments the next day. Experts suggest a relaxing bedtime routine, starting an hour or two before lights-out time, to help your body transition into sleep.

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Cheryl Hines

Best known for her role as Larry David's wife on the HBO series Curb Your Enthusiasm, the actress has suffered from insomnia for more than 20 years - but a different type of insomnia than most might expect. "At first, I wasn't even aware that I was experiencing insomnia, because my issue wasn't just being unable to fall asleep when I went to bed at night. I was also dealing with waking up in the middle of the night and then not being able to get back to sleep," Hines said in a press release. Her doctor recommended a regular sleep schedule, not exercising close to bedtime, and trying Ambien CR.

In 2007, Hines teamed up with the American Academy of Nurse Practitioners Foundation to raise awareness and provide solutions for insomnia through a campaign called "Why Count on Sheep to Sleep?"

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James Mercer

At least one source described the lead singer of indie-rock group the Shins as having "crippling insomnia" around the time of the January 2007 release of the album Wincing the Night Away. Mercer told MTV that he does struggle with some insomnia, but it's not anything he would call "crippling."

"It's something I wrestle with once in a while if I've got a stressful situation or something to deal with," he said, adding that the album's "nocturnal vibe" was inspired by his wandering through his neighborhood late at night.

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Jennifer Lopez

Some stars make it a priority to get enough sleep. Actress-turned-singer Jennifer Lopez swears by eight hours a night as her number-one beauty secret. "Sleep is my weapon," she once said. "I try to get eight hours a night. I think what works best is sleep, water - and a good cleanser."

But with the birth of her twins in 2008, she was forced to sacrifice some of that beauty sleep. She told People magazine the babies were keeping her up until 6 a.m.

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Jimmy Kimmel

Late-night host Jimmy Kimmel told The New York Times Magazine that he suffers from narcolepsy. He said the disorder has caused him to fall asleep in his car or drift off during afternoon writers' meetings - "not the best way to make people feel good about their material," he joked. In 2003, he told Esquire that he wasn't diagnosed until adulthood and that the disorder feels like "somebody's gently sitting on your brain."

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Justin Chambers

In January 2008, Grey's Anatomy star Chambers checked into the UCLA Medical Center's psychiatric ward to get help for his long-time sleeping problem. "It's a biological sleep disorder," he told People magazine. "Your mind keeps racing, and your body is tired. It wants to go to sleep, but it can't." The father of five says he checked into UCLA after two months of sleeping no more than an hour a week.

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Mariah Carey

Singer Carey, 39, takes sleeping to a new extreme. "I've got to sleep 15 hours to sing the way I want to," she told Interview magazine in 2007. Most adults only need seven to nine hours a night. Sleeping for half the day would likely strike most doctors as strange. So would Carey's humidifier habit: "Literally, I'll have 20 humidifiers around my bed," she told V magazine. "Basically, it's like sleeping in a steam room." While the machines can help to moisten dry air and soothe sore throats, usually one will do.

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Keith Olbermann

Olbermann, the former host of MSNBC's Countdown, suffers from restless legs syndrome, according to a 2008 profile in The New Yorker. He told the magazine that his RLS keeps him from sleeping at night because of an intense urge to get out of bed and move around. He takes medication that helps him get some shut-eye. On at least one occasion, he's even taken to answering emails on his BlackBerry while waiting for the meds to kick in - a tactic that most doctors wouldn't recommend.

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Reggie White

NFL defensive lineman and Hall of Famer White passed away in 2004 at the age of 43. Although he died from pulmonary sarcoidosis, White also had sleep apnea, a disorder that affects many football players because they are often heavy and have short, thick necks. White's wife, Sara, together with the Sleep Wellness Institute in Wisconsin, founded the Reggie White Sleep Disorders Research and Education Foundation to help raise awareness about the danger of sleep apnea.

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Jon Stewart

We're not sure how serious his claims were, but in January 2008, Stewart told The Daily Show viewers that he's had insomnia for years because of something he calls "The Jimmy Legs." He finally found a cure with medications for restless legs syndrome, but he's a little skeptical about some of the possible side effects.

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Leonardo Da Vinci

The Renaissance man reputedly slept almost exclusively in power naps: 15-minute siestas every four hours, equaling a shockingly low total of 1.5 hours a day. While we can't be sure he actually slept this way, research has proved it could be possible. Claudio Stampi, a sleep researcher, found that the catnap sleep schedule is possible to follow, but not for long. Da Vinci most likely could not have slept this way for more than two months, or he would not have been the scientist, mathematician, and artist we know him as today.

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Kelly Clarkson

Clarkson told Self magazine that she composes songs and lyrics as she's trying to drift off to sleep. The first American Idol winner can't wait until morning; she feels she has to immediately write down or record her ideas. "That's why I have a hard time sleeping," she said. "A lot of those times are at night." Clarkson may be on to something: Sleep experts often recommend keeping a notebook next to your bed so you can write down thoughts or worries that threaten to keep you awake; they suggest that you put them out of your mind and refer back to them the next day.

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Eminem

Rapper Eminem spoke with Complex Magazine about his sleeping problems in 2006. He says he was so busy on tour that he had trouble sleeping without medication, especially on buses or airplanes. "It drove me insane," he told Complex. "I just medicated myself to death." He later checked in to rehab to get help.

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Thomas Edison

Reputedly, the inventor slept only four to five hours a night, calling sleep a waste of time. But according to the Edison National Historic Site, he took frequent catnaps. After napping, he would be able to stay up all night working, but he most likely caught up on his shut-eye the next day.

Sleep experts caution against daytime naps for people who have insomnia because it can further disrupt your sleep schedule - but for people who don't mind getting their z's in smaller segments at different times of the day, they can be a good way to get much needed rest.

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Martha Stewart

Convinced that there's "not enough time in the day," Stewart rises before dawn and sleeps about four hours a night, People magazine reported in 1995 - an odd trait for someone who lends her name to elegant mattress and bedding collections.

But watch out: Studies show that averaging less than five or six hours a night can be hazardous to your health, compromise your immunity, and put you at risk for heart problems, which may shorten your life span.

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Winston Churchill

The British prime minister made up for lost shut-eye by napping during the day. According to The New York Times, Churchill said that if you nap, "you will be able to accomplish more. You get two days in one - well, at least one and a half."

As long as napping during the day doesn't leave you restless at night, doctors agree that a quick snooze can be good for your health and productivity. Others have followed his lead; rumored political nappers include Bill Clinton, John F. Kennedy, Ronald Reagan, and Napoleon.

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Rosie O'Donnell

After years of what she calls "absurdly loud" snoring, O'Donnell was diagnosed with sleep apnea. She discussed her testing and treatment on The View in November 2006, telling viewers she had suspected that she had sleep apnea but was embarrassed by the link between the disorder and being overweight. Dr. Michael Breus, sleep expert and author of The Insomnia Blog, discovered that O'Donnell stopped breathing more than 200 times a night, sometimes for about 40 seconds.

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Nicole Jeray

Pro-golfer Nicole Jeray suffers from narcolepsy, but she doesn't let the disorder interfere with her game on the green. She takes medication to treat her symptoms, but she also watches what she eats and tries to avoid having a stressful, busy schedule, according to her website. She also worked with the Narcolepsy Network to promote awareness of the disorder.

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Brooke Burke

Not all celebs are up at night because of sleeping disorders. Like many new moms, TV personality Burke knows what it's like to be up all night with young children. "I am getting desperate for sleep," she wrote on her blog in September 2008. "I'm thinking about a sleep nurse to train [them] to sleep through the night."

Getting enough sleep during pregnancy and as a new mom can help women combat fatigue, fight off illnesses, and become less likely to develop postpartum depression, so it's important to ask for help from family and friends.

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Louise Bourgeois

French artist Bourgeois, who died in 2010 at the age of 98, first experienced insomnia in 1939, according to The Guardian. Instead of suffering through long, sleepless nights, however, she used the extra time to get work done. She created the aptly named The Insomnia Drawings by recording all the thoughts and images that came to her mind during a particular bout with the disorder in the mid-nineties. She's pictured here with her sculpture Sleep II.

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Natalie Pinkham

The British sportscaster and reality show competitor (pictured here with her Dancing on Ice partner) is a sleepwalker. She told the Daily Mail newspaper that she has been wandering out of bed and performing strange acts in her sleep for as long as she can remember; once she was found in a hotel lobby, using her hairbrush as a microphone and conducting an imaginary interview. Pinkham also suffers from other parasomnias, including severe nightmares and night terrors, and faces anxiety when going to sleep at night. After a stay in a sleep clinic, the Daily Mail reports, she finally found relief in 2009 when her doctor prescribed a variety of medications, including an iron supplement.

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Brad Pitt

Now that the Jolie-Pitt clan is six children strong, Pitt has more mouths to feed. But the kids have also been keeping him up nights, he told reporters at the 2008 Toronto Film Festival. "Everyone is healthy. No sleep though," Pitt said. "Sleep is something you long for, but it's all right. We'll get it."

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Michael Jackson

The questions surrounding Michael Jackson's sudden death in June 2009 seem to focus on one fact - the King of Pop couldn't sleep. Instead of standard sleeping pills, he relied on a mixture of powerful sedatives, including propofol, an anesthetic used to keep people unconscious during surgery.

The night before he died, Jackson reportedly lay awake, immune to anti-anxiety medications and muscle relaxants, until receiving a propofol injection and falling asleep around 11 a.m. Shortly after, the performer stopped breathing. His doctor's unorthodox methods have resulted in a homicide ruling, and, hopefully, served as a wake-up call to those who go to extreme and unsafe lengths to get some shut-eye.

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Heath Ledger

The Australian actor died in January 2008 at age 28, and the cause of his death has been linked to various prescription medications, including sleeping pills. In a 2007 interview with The New York Times, Ledger said he sometimes slept for only two hours a night when work was stressing him out, and on one occasion he took multiple Ambiens to fall asleep, only to wake up soon after.

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DJ AM

The celebrity disc jockey, whose real name was Adam Goldstein, died of an apparent drug overdose in August 2009, almost a year after surviving a plane crash that left him with third-degree burns and post-traumatic stress disorder (PTSD).

A recovering drug addict, Goldstein had reportedly been clean for 11 years but started using again just days before his death. Friends say that prescription anti-anxiety medication may have caused him to crave harder drugs, and one addiction specialist told People magazine that former addicts with insomnia, a common symptom of PTSD, are at least three times a greater risk for relapse than people who sleep well. Goldstein told People in late 2008 that he worried about having fire-related nightmares "forever."

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