Most of what we know about sleep has only been researched in the last 25 years. Scientists and researchers around the world are learning more about sleep every day (and night) and are teaching us things we never dreamed of (sorry for the pun). We have compiled a list of 22 of the most interesting and surprising facts about sleep that you may not know.
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12% of people dream entirely in black and white. Before the introduction of color television, only 15% of people dreamed in color, which is why older people are more likely to dream in black and white than younger people.
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Cats spend two-thirds of their lives sleeping. This won’t surprise most cat owners. Every couch is a sleeping couch for them, or otherwise, it’s your favorite chair or computer keyboard.
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A giraffe needs only 1.9 hours of sleep per day, while a brown bat sleeps for 19.9 hours per day.
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Humans spend one-third of their lives sleeping. This varies with age, of course, but on average, it’s about one-third—quite a lot when you think about it.
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The record for the longest time without sleep is 11 days. This was set by a California student named Randy Gardner in 1964. However, it’s definitely not advisable to attempt this, as Randy experienced extreme sleep deprivation, and others have died trying.
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It’s not uncommon for deaf people to use sign language in their sleep.
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Dysania (sleep phase syndrome) is the condition where it is difficult to get out of bed in the morning. We all find it hard to get out of bed occasionally, but for those with dysania, it’s especially difficult. It’s most likely a form of chronic fatigue syndrome.
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Parasomnia is a term that refers to unnatural movements during sleep. Some people have even committed crimes due to parasomnia.
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The feeling of falling while half asleep and jerking awake is called a "hypnic jerk." It involves an involuntary muscle spasm or twitch. No one is entirely sure why hypnic jerks happen, but they can be increased by anxiety, caffeine, or physical activity near bedtime. They are more common in young people and decrease with age.
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It is estimated that up to 15% of the population are sleepwalkers (according to the National Sleep Foundation). It remains a myth that you shouldn’t wake someone who is sleepwalking.
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One in four couples sleep in separate beds.
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Sleep deprivation kills faster than food deprivation.
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Those born blind have dreams that don’t involve vision but rather emotions, sounds, and smells. Interestingly, the timing of a person’s blindness in life affects their dreams.
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Within 5 minutes of waking, 50% of a dream is forgotten. After another 5 minutes, 90% of it is gone. Sigmund Freud believed this happened because dreams represent our repressed thoughts, and our brain wants to get rid of them quickly. However, it’s more likely that the brain is simply being used much more once we are awake, which causes us to forget most of what we dreamed.
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Pain tolerance is reduced by sleep deprivation. Studies suggest that cutting a person’s sleep in half drastically lowers their pain threshold, although the reason isn’t entirely clear.
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41% of the British population sleeps in the fetal position, according to research by Professor Chris Idzikowski, director of the Sleep Assessment and Advisory Service.
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Sleep experts have found a direct link between people’s preferred sleeping positions and their personalities. According to Professor Idzikowski, people who sleep in the fetal position "may appear tough but are actually sensitive souls at heart."
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Ideally, falling asleep at night should take 10-15 minutes. If it takes less than five minutes to fall asleep, it’s often due to significant sleep deprivation.
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Humans are the only mammals that willingly delay sleep.
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Sleeping on your stomach can aid digestion. Hands should be positioned over the pillow to allow you to be in a "free" position. Sleeping on the left side is said to help reduce heartburn.
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According to a British study, high earners (£65 - £75,000) reportedly get the best sleep, as reported by the Sleep Council.
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Anxiety is not the main emotion in nightmares.