In China, teachers allow children to sleep in class for around 20 minutes to help improve their learning.
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Some people have a "natural alarm clock" allowing them to wake up when they want. This is actually caused by a burst of the stress hormone adrenocorticotropin.
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You forget 90% of your dreams.
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If you hold farts in during the day, they'll just come out when you sleep.
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There's a love mattress that is specifically designed for couples who sleep on each other's arms.
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