Celebrities lead fabulous lives—jetting across the country on a whim, partying at late-night hot spots—so it’s no surprise that sleep may not always be a number-one priority. When prescription sleep medication was implicated in Heath Ledger’s tragic death in January 2008, it raised the question of whether other members of the glitterati were spending their nights tossing and turning. 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. Here, see who gets too much and not enough—and what you can learn from each of them.

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.

Renee Zellweger
As a result of her busy schedule, Zellweger, 39, 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. 

Cheryl Hines
Known for her role as Larry David’s wife on the HBO series Curb Your Enthusiasm, actress Hines, 43, 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?"

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, 37, 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.

Jennifer Lopez
Some stars make it a priority to get enough sleep. Actress-turned-singer (and recent triathlete!) Jennifer Lopez, 39, 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."

Jimmy Kimmel
Late-night host Jimmy Kimmel, 40, 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.”

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 best 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.

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.

Kelly Clarkson
Clarkson, 26, 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.

Rapper Eminem, 36, 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.

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. 

Martha Stewart
Convinced that there’s “not enough time in the day,” Stewart, 67, 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.

Brad Pitt
Pitt, 44, has more mouths to feed and extra diapers to change, now that the Jolie-Pitt clan is six-children strong. 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.”