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Sleep myths that may be keeping you from a good night's rest

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(CNN) What are your sleep myths and facts? You know, the things you are absolutely sure you should do -- and not do -- to get a good night's sleep. Studies show that most of us are practicing bad sleep habits without knowing it -- which can lead to serious health consequences.

How do your beliefs about sleep stack up?

Myth or fact? If you lie in bed long enough, you'll fall asleep

Myth. When it comes to sleep no-nos, experts say this is a big one. Lying in bed, even with your eyes closed, for more than 15 to 20 minutes is one of the worst things you can do because it will train your brain to associate the bed with a lack of sleep. It can lead to chronic insomnia, Michael Grandner, a clinical psychologist and sleep expert, told CNN in an earlier interview.

"It's counterintuitive, but spending time in bed awake turns the bed into the dentist's chair," said Grandner, who directs the sleep and heath research program at the University of Arizona and the Behavioral Sleep Medicine Clinic at the Banner-University Medical Center in Tucson, Arizona.

"You want the bed to be like your favorite restaurant, where you walk in and you start getting hungry, even if you just recently ate," he added. "You want the bed to do that for sleep."

Myth or fact? You shouldn't check your smartphone if you wake in the night

That's a fact. Banning smartphones (or any electrical device that emits blue light) from the bedroom an hour or so before bed and all through the night is a must for good slumber, experts say. Light tells the body to stop producing melatonin, the body's natural sleep aid, and studies have shown that blue light is especially toxic to sleep.

So when you get out of bed after 20 minutes of sleeplessness, avoid bright light, watching TV or checking social media. Instead, keep the lights dim and do something mindless, such as folding socks. Better yet, try doing one of these tricks to relax your mind and ready yourself for sleep.

Myth or fact? You shouldn't let your dog or cat sleep in your bed

Actually, it depends. Not long ago the answer from any sleep expert would have been a definitive no. But today, some experts are seeing the benefits of cuddling in bed with a furry loved one, at least for a select group of people.

In some cases, people with anxiety, depression or PTSD could benefit from sleeping with a pet in the bed, said Dr. Raj Dasgupta of USC's Keck School of Medicine.

"Pets are making a comeback," said sleep specialist Dr. Raj Dasgupta, an associate professor of clinical medicine at the Keck School of Medicine at the University of Southern California. "For people with anxiety, depression or post-traumatic stress, having a bed buddy may be helpful in fostering sleep."

Children, too, may sleep just as well with a pet accompanying them, studies have shown. But people who are light sleepers may find their sleep disturbed by too many "micro-wakenings," which can be harmful to health. In those cases, pet owners may find they need to keep pets on the floor at night or ban them from the bedroom entirely.

Myth or fact: Exercising in the evening will disrupt sleep

That's a myth that used to be a fact "in the olden days," Dasgupta said.

"Now the data shows that exercise at any time is better than not exercising due to all the medical benefits, and it helps with stress reduction, which aids sleep," he said. "The data about not exercising at night is when you're doing extreme workouts like Olympic athlete-type exercises."

People who exercised for 35 minutes right before bed slept as well as they did on nights when they didn't exercise at all, a 2011 study found. If working out at night does affect your sleep, experts suggest exercising early in the evening so your heart rate and body temperature can return to normal before you hit the hay.

"If you ask me when's the perfect time to exercise, I think it's gonna be in the morning and outside in daylight. It resets the circadian rhythm and starts the day off with vigor," Dasgupta said. "But if nighttime exercise is best for you, that's fine."

Myth or fact? You can catch up on sleep on the weekends

Who doesn't believe this one? Sadly, the science says we're wrong. We may feel better after sleeping in on a Saturday or Sunday morning, but it will be to the detriment of our overall sleep health, experts say. By changing your wake-up time and bedtime on weekends (or day to day), your sleep rhythms aren't predictable, which can alter the body's circadian rhythm.

"You want to build a reliable rhythm, much like the drummer counting the beat for the band," Grandner said. "By controlling when you wake up and go to bed, you're setting the beat."

Overcome this myth by going to bed and getting up at the same time each day, even on weekends, vacations or after a night of poor sleep.

"The brain likes regularity and predictability," he added. "Waking up at the same time every day and then adding light and movement as soon as you wake up will set your other rhythms for the day and give you increased energy and mood."

Check out more sleep myths and facts with our interactive sleep quiz. Happy snoozing!