Everything You Always Wanted to Know About Sleep* (*But Were Afraid to Ask)
Sleep Trivia from 65 issues of The Sleepscape
In each edition of our weekly Sleepscape newsletter, we highlight a different “Question That Keeps Us Awake.”
There have been so many interesting topics that we just had to combine them all into one jumbo-sized list!
We hope that you enjoy reading them as much as we’ve enjoyed researching them.
🐻 Nature’s Best Sleepers
Q: Which animal hibernates the longest?
A: Certain species of land snails can hibernate — and estivate, as it’s called in the summer — for up to three years, requiring only moisture to survive. (We were envious until reading that they only did so after coating themselves in mucus.)
Q: Is it true that because sharks have to stay in constant motion to breathe, they never sleep? 🦈
A: Sharks do indeed sleep… just not in the conventional sense. Like many underwater creatures who need moving water on their gills to breathe, the shark’s brain never powers down completely — instead, it switches to a low-function mode (similar to when we daydream) that allows it to remain in motion and stay alert to prey or danger.
This means that sharks don’t sleep deeply enough to dream, which is probably for the best: we don’t need them coming up with any new ideas.
Q: Which animal sleeps the most?
A: While your cat may be a pro-level sleeper, getting up to 16 hours of slumber a day, the brown bat sleeps an average of almost 20 hours. Conversely, giraffes get by on less than 2 — many adult giraffes sleep only 30 minutes each night!
Q: Do animals fight falling asleep the same way humans do?
A: Nope, even that stubborn mule sleeps when his body tells him to! Humans are the only animal willing to forgo slumber to binge another episode of The Office.
(But c’mon, up next is the one with Kevin and the pot of chili… how can you not stay up for that?)
Q: Is it true that I swallow an average of 7 spiders per year in my sleep?
A: Actually, the number of spiders you swallow in your sleep each year could be as high as 100! But you can rest easy: it’s most likely zero.
As studying this phenomenon would be nearly impossible (some poor soul would have to carefully review footage of you sleeping every night), you can be assured that these statistics are spun from urban legend.
They’re also quite improbable, as spiders tend to avoid humans.
However, there are reports that you have two wolves living inside you...
Q: Do plants sleep?
A: Surprisingly, plants do sleep! When the sun goes down, the process of photosynthesis stops and plants use nighttime to heal and grow, just like we do. What they dream about, however, is anyone’s guess.
Q: Do trees sleep at night?
A: Even trees sleep! According to research published in Frontiers in Plant Science, at night trees’ branches droop. As photosynthesis stops, the leaves of some trees will also curl up. And during winter they hibernate, ceasing all but a few functions necessary for survival.
Q: Is it true that people have a harder time sleeping during a full moon?
A: Studies conducted at Switzerland’s Basel University showed that during a full moon their participants took an average of 5 minutes longer to drop off, slept for 20 fewer minutes and spent 30% less time in deep sleep.
And let’s not forget how difficult it is for werewolves…
🤔 Sleep Oddities
Q: Are there people who are afraid of dreaming?
A: If you suffer from PTSD or a nightmare disorder, you could develop oneirophobia, the fear of dreaming. This stems from the loss of control (in dreams, quite literally anything can happen to you). Talk therapy has proven successful for coping with and overcoming this phobia, and many counselors specialize in this field.
Q: Is it true that I should never wake a sleepwalker?
A: The claim that you should never wake a sleepwalker stems from an ancient belief that the soul leaves the body during sleep, and waking the sleepwalker would leave the soul unable to reunite with the body.
While it’s been suggested that waking the person could cause a heart attack, most doctors agree that people are far more at risk to themselves by continuing to sleepwalk. The best way to avoid the confusion and disorientation that can occur from waking a sleepwalking loved one is to just gently guide them back to bed.
Q: Why do I sleep so well after a big cry?
A: When you cry, your heart rate speeds up and your breathing slows down. This reduces the amount of oxygen to your brain, which causes drowsiness. The emotional workout, as well as the relief afterward, also contributes to feeling sleepy. While there are much more pleasant ways to get a good night’s slumber than crying yourself to sleep, letting those emotions out is a healthy and rewarding thing.
Q: Can people sleep while standing?
A: At some point you’ve probably been so tired that you’ve fallen asleep on your feet. But as you discovered, you can’t stay dozing in that position for long.
Though a group of Buddhist monks in Scotland claim to have perfected the art of sleeping while standing, the difficulty comes when you hit REM sleep. During this stage, your body relaxes your muscles to keep you from acting out your dreams.
Unfortunately, this also means the muscles holding you in an upright position will go limp. Hello, floor.
Q: What’s the longest someone has ever gone without sleep?
A: The Guinness Book of World Records reports that Maureen Weston of Peterborough, Cambridgeshire went 14 ½ days without sleep during a rocking-chair marathon in 1977.
Due to the health risks posed by sleeplessness, Guinness capped the record and discourages anyone else from attempting it. Rocking chairs, however, remain highly recommended.💺
Q: Why do some people sleep with their eyes open?
A: Being unable to close the eyelids during sleep, either fully or partially, is what doctors call nocturnal lagophthalmos (or as the rest of us refer to it, “kinda creepy”).
Up to 20% of us have experienced it at some point in our lives, though we usually outgrow this often-genetic condition during childhood.
Q: How did this end up being “my side” of the bed?
A: If you’re a woman, studies show you’re among the 80% who actually chose your side of the bed, with just 20% of men being the one to make the selection. In fact, 20% of the women surveyed shared that a request to switch sides is a relationship dealbreaker.
Take heed, guys: let her sleep wherever she wants.
Q: Which country’s citizens get the most sleep?
A: French citizens top the chart, with the average citizen getting nearly 9 hours of sleep each 24-hour period.
Bonne nuit, mes amis!
Q: When falling asleep, why do I sometimes hear a sudden crash of cymbals that wakes me up?
A: Presuming you don’t live with a percussionist, the cymbal crash is an ominous-sounding phenomenon known as “exploding head syndrome.” (Some experience it as a gunshot or clap of thunder instead.)
Sleep researchers aren’t sure what causes it, or even how widespread it is. However, treatments for anxiety seem to effectively reduce occurrences in patients.
Q: Is it true that I’m taller asleep than when awake?
A: Believe it or not, your height does increase when you sleep — by about a third of an inch. This is because when you’re sitting or standing, the cartilage discs of your spine compress. Without gravity pulling them downward, they’re able to expand and grant you a temporary height boost that you can legitimately add to your dating profile.
Q: Is it weird that I sleep best with a teddy bear or blanket from childhood?
A: Not weird at all! In fact, ⅓ of adults report being soothed by sleeping with a childhood blanket or stuffed animal.
Q: Is there a scientific term for talking in my sleep?
A: You know it! The scientific terminology for talking in your sleep is somniloquy, and it’s experienced at least occasionally by 50% of children and 5% of adults.
We think that “somniloquist” also adds a poetic flair to the Special Talents section of any resume.
📚 Sleep History 101
Q: Are nightmares named after horses?
A: The horse’s noble name remains untarnished. The “mare” in nightmare actually has Old English and Scandinavian roots — it’s a term for a goblin that would ride on slumbering victims’ chests and plague them with terrifying dreams.
Q: Who were the Brothers Grimm?
Creators of longtime bedtime favorites like Cinderella, Beauty and the Beast, Rapunzel and Sleeping Beauty, Jacob L. K. and Wilhelm C. Grimm were born in mid-1780s Hanau, (what is now) Germany.
The brothers both cultivated a passion for German folklore while attending the University of Marburg, and the rest, as they say, is history. Wherever you may travel, people will be familiar with these tales that have been translated into 100 languages. Not to mention Disney films galore…
But the Grimms didn’t just spin tales to lull fussy wee ones to sleep. Their methodology of gathering and recording folklore became the basis for academic anthropological studies known as folkloristics.
Q: Who was the first scientific dream researcher?
A: University of Chicago Ph.D. grad student Eugene Aserinsky began studying sleep and dreams in the early ’50s. In 1953 he and his Ph.D. advisor and mentor, Nathaniel Kleitman, published a paper on the correlation between rapid eye movement (REM) sleep and dreaming, establishing themselves as the pioneers of dream research.
Q: Have any inventions been inspired by dreams?
A: Many inventions have actually been inspired by dreams. Among them are Tesla’s AC generator, Howe’s sewing machine, the periodic table--even Google!
Q: Where does the term “tuckered out” come from?
A: “Tucker” is early 19th century New England slang, meaning weary. It’s often expanded to “plumb tuckered out,” with “plumb” being a synonym for completely.
Q: Who was the first TV couple to share a bed?
A: The very first couple on TV to have but one bed in the bedroom were Mary Kay and Johnny Stearns of Mary Kay and Johnny, a sitcom that debuted all the way back in 1948.
They dodged the Hays Code — entertainment’s moral guidelines of the time — because they were married in real life. Other TV couples, though, still slept Bert-and-Ernie style until the ’70s. Censorship regulations eventually caught up to logic, and TV couples could finally ditch the twin beds.
Q: Where did the term “40 winks” come from?
A: The expression “40 winks” (to describe a nap) first saw print in 1821 in The Art of Invigorating and Prolonging Life by Dr. William Kitchiner, though the expression was already in conversational use. A similar expression, “9 winks,” was also common at the time.
The phrase’s history is lost to oral tradition, though the “40” is believed to be tied to the number’s Biblical significance.
🧚 The Dream World
Q: Why can some people remember their dreams so easily when I can barely recall any details?
A: According to a study by France’s Lyon Neuroscience Research Center, the temporoparietal junction, the section of the brain that processes emotions and information, is more active in those who have better dream recall. Their prefrontal cortex, which deals with abstract thoughts, also tends to get more use during waking hours. In short, some are just biologically wired for better dream recall.
But you could see some personal improvement by giving the associated areas of the brain a regular workout. Learning a foreign language, doing improv, conversing with strangers and other activities that rely heavily on social and interpretation skills will flex the right gray matter.
Q: Is it weird that all of my nightmares are embarrassing rather than scary?
A: According to the University of Montreal’s dream researchers, fear is only the most prevalent emotion in about a third of nightmares.
Instead, embarrassment, guilt, disgust, sadness and confusion drive the majority of bad dreams. (So your recurring “nude on stage” nightmare is totally normal.)
Q: How much of my sleep time is spent dreaming?
A: Though your dreams may seem to pass in an instant, you’ll likely have 4-7 dreams over the 1-2 hours you spend dreaming each night. Most of these — upward of 90% — are forgotten within 10 minutes of waking.
Q: I don’t remember any of my dreams. Am I dreaming at all?
A: Even though you may not be able to recall your dreams, it’s extremely likely you’re still having them — from infancy, we dream for an average of two hours every night.
During REM sleep (the prime dreaming stage) your brain releases a dose of vasotocin, a forget-me-now chemical that cleans up after dreams and makes them difficult to recall.
Use of alcohol or marijuana, prescription medications, sleep disorders, PTSD and other factors can also inhibit your ability to remember your dreams.
Q: Does the subconscious “create” the strangers in our dreams?
A: Though the subconscious drives their personalities, it doesn’t actually create those background people in your dreams. They’re all people you’ve seen at some point, even if you weren’t aware you noticed them. The janitor you passed in the hallway, the woman sitting near you on the train, the FedEx guy carting a package down the sidewalk — they could all be playing a cameo role in your next dream.
Q: Why can’t I read a book in my dreams?
A: Certain areas of your brain are put in low-power mode while you sleep, and among them is the center that controls language interpretation. This affects our ability to do things like reading, writing, dialing a phone number or telling time in our dreams.
Many lucid dreamers will attempt these sorts of tasks to help determine when they’re in a dream state.
Q: Could a machine read my dreams?
A: Don’t worry, that private dream you had about your high school crush is still secret. For now, anyway.
A team of scientists at Kyoto University has built a machine that can read dreams, the catch being that it currently only has a 60% accuracy rate, and can only detect basic events and ideas in dreams. However, they are continuing to refine it, improving its accuracy and ability to detect more specific content. To which we say: 😨.
Q: What’s the most common emotion experienced in dreams?
A: Research has determined that anxiety is the most common emotion experienced in dreams, followed by fear, anger and sadness. These aren’t exactly the ingredients for sweet dreams — but there may be a solution.
One theory suggested by sleep scientists is that dreams may be simulations created by your subconscious designed to work through emotional issues plaguing you in the waking world. If true, your dream anxiety may be tied to your daytime anxiety — and it stands to reason that the more time you spend working through these problems in the waking world, the less likely they’ll be to pervade your slumber.
Q: Is it normal to dream only in black and white?
A: Just 12% of the population dream exclusively in black and white today. However, before the advent of color television, about 75% of those participating in clinical studies reported rarely or never dreaming in color.
With the increasing popularity of VR entertainment, we can expect our dreams to become even more immersive.
📈 Handy Hacks
Q: Can a warm bath at bedtime help me sleep?
A: Get out the Mr. Bubble — a joint study by the University of Texas Health Science Center at Houston and the University of Southern California revealed that a warm bath at bedtime improved sleep onset time by about 35%.
Add some lavender-scented bath salts, a few candles, a good book and a dire warning to any who would dare interrupt your spa time, and you know it’s gonna be a great night of sleep.
Q: Is reading at bedtime truly beneficial to sleep?
A: Those bedtime stories are more essential than you might think: a University of Sussex study revealed that just six minutes of reading at night can reduce stress by up to 68%.
And since anxiety is the #1 cause of insomnia…
Q: Will blasting the radio and opening the window (or turning up the AC) help if I’m drowsy while driving?
A: Any additional alertness gained from icy air or cranking your radio will be temporary, as your weary body and mind will quickly adjust to the change in environment.
Instead, experts recommend pulling over for a short nap of 20 - 30 minutes.
Q: Will listening to music at bedtime help me sleep?
A: According to a study in the Journal of Advanced Nursing, those who listened to 45 minutes of classical music at bedtime experienced better sleep quality than those who didn’t. Music without lyrics and with a tempo of 60 - 80 bpm (typical of classical and jazz) is ideal.
🥱 Naptastic Facts
Q: Does any culture embrace napping at work?
A: In Japan, napping at work is a sign of diligence and being present. The 1,000-year-old practice of napping in public, or inemuri, is also very common on commuter trains, in parks and cafes.
Q: Will a nap during the day impair my ability to sleep at night?
A: As long as your naps are kept short — around 20 or 30 minutes — they’re a fantastic way to revitalize midday without causing sleep loss at night. In fact, we’re naturally wired for naps: your body automatically secretes a burst of melatonin every afternoon to help lull you to sleep (hence your post-lunch energy dip).
Q: Why do I always get sleepy in the mid-afternoon?
It’s easy to blame a big lunch or a boring project, but being sleepy in the afternoon is actually part of your circadian rhythm. From ~2:00 - 4:00 PM (and AM) your body’s core temperature naturally drops and your brain produces more melatonin, which makes you drowsy. This is the ideal time for a short nap (no more than 30 minutes).
If your boss doesn’t allow naps, though, you can instead quit immediately take a brisk walk to get the oxygen flowing in your bloodstream.
🧪 The Science of Sleep
Q: What’s the purpose of yawning?
A: The truth is, yawning remains one of the great biological mysteries. Scientists aren’t entirely sure why we yawn, but they do have some sensible theories.
Yawning can cool an overactive brain, oxygenate and stimulate a body that’s been idle too long, or just provide a means to stretch the lungs. Adding to the mystery, for some reason we yawn less in cooler temperatures.
You may have even yawned just reading this, as yawning is highly contagious (we delve into why in another issue), even across species!
Q: Why is yawning so contagious?
A: Yawning when you see someone else do it — even in a video — is a sign of empathy and bonding, according to a study by Baylor University. Scientists are still trying to understand exactly why yawning is so contagious, but it’s believed to have been a social cue in early humanity’s development to signal to others of the tribe that it’s time for sleep.
We’re not the only ones susceptible to sympathetic yawning — chimps and dogs do it, too!
Q: Why is it so difficult to sleep in an unfamiliar place?
A: No matter how luxurious and secure your new surroundings may be, one hemisphere of your brain automatically remains more active when you sleep in a new location for the first time. Your brain does this so you can more readily respond to perceived “threats” in unfamiliar surroundings, so the phenomenon isn’t without benefit — but it does tend to tank your sleep quality.
Q: Is there a medical term for my difficulty getting up in the morning?
A: Groggily reaching for the snooze alarm a third time and frowning at the sunshine creeping into your room could be signs of dysania. The Cleveland Clinic highlights nutritional deficiency and depression as key causes, among other potential issues. It might be time for a checkup — your doctor could hold the key to you becoming a chipper morning person.
Q: My dog recently passed away, and now I’m having problems sleeping. Is this common?
A: Insomnia is a natural part of the grieving process. The painful thoughts, anxiety and sense of loss surrounding a loved one’s passing contribute to difficulty getting to sleep (and staying there).
It can take time to get back into normal sleep patterns, but getting to sleep will become easier as the healing process takes place.
Q: Why am I more prone to snacking after a bad night of sleep?
A: Though junk food packaging is especially appealing, you can blame your urge to snack after a restless night on two hormones: ghrelin and leptin.
While you’re unable to sleep, your body is busy producing more hunger-inducing ghrelin — and at the same time, supplies of appetite-suppressing leptin dip. This keeps you from feeling full after eating breakfast… and after the donuts that followed it.
Q: Do men and women require the same amount of sleep?
A: Ladies, feel free to hit the snooze alarm a couple of extra times. According to a UK study, women need an average of 20 more minutes of sleep per night than men. This is because women tend to multitask more, which uses more of the brain’s real estate. That in turn means additional time is needed to get that cerebral charge back up to 100%.
Q: How long does it take the average person to fall asleep?
A: Sleep latency--the amount of time that it takes you to fall asleep after closing your eyes--was first examined by Stanford University researcher William C. Dement. His studies determined that it takes an average of 7 minutes for alpha waves to dominate the brain, and 10-20 minutes to fall fully asleep.
Taking less than 5 indicates that you could be sleep-deprived, and if you’re still awake after 20 minutes, sleep experts recommend you get up and engage in a non-stimulating activity for a while until you’re ready to try sleeping again.
Q: What’s the most common sleep position?
A: If you sleep like a baby when you’re in the fetal position, you’re in good company: WebMD reports this as the go-to sleep style for more than 40% of the population.
You back-sleepers are the renegades, representing a mere 8%. (We applaud your rugged individuality.)
There you have it, our complete collection of Questions That Keep Us Awake.
Keep an eye on your inbox for upcoming editions of the Sleepscape, featuring your weekly dose of sleep trivia — along with a hand-picked selection of the internet’s best sleep tips, products and curiosities.
If you haven't had enough of sleep trivia, check these articles out:
Many Cultures Don't Use Mattresses — Here's What They Sleep on Instead
5 Surprising Reasons Your Dog Should Sleep In Your Bed Every Night
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