31 things you didn't know about sleep


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Have you ever thought about what sleep actually is? It's not as straightforward as it may initially seem. Gaining a better understanding about sleep will help doctors treat a variety of sleep disorders. Healthy Sleep, a resource from the Division of Sleep Medicine at Harvard Medical School, is a website that aims to help the general public understand sleep and to get the sleep they need.

We may not be able to define sleep, but if there's one thing we can all agree on is that we feel sharper and more focused when we get enough of it and lousy when we don't. According to the Cleveland Clinic's HealthHub, we spend about one-third of our time on the planet asleep. If we do the math, that's about 16 hours a night as infants, 9 hours as teens and 7 to 8 hours as adults.

Unfortunately, getting the optimal 7 to 8 hours is easier said than done for many people. According to the Centers for Disease Control and Prevention March 2011 Morbidity and Mortality Weekly Report, it is estimated that 50 to 70 million Americans have a chronic sleep disorder.

We burned the midnight oil scouring the Internet for these 31 facts about sleep that you may not have already known.


1. We are the only mammals that delay sleep on purpose.


2. Insomnia is not defined by the sleep you lose each night, but by the drowsiness, difficulty concentrating, headaches, irritability and other problems it causes each day.


3. A sleeping person may appear inactive, but some functions of the brain and body are actually more active during sleep than when we're awake.


4. Artificial lighting, such as room lights, TVs, computers and other electronics, may be contributing to our inability to get an adequate amount of sleep. Scientists and doctors are contemplating how this prolonged exposure to light might interfere with our bodies' naturally programmed sleep patterns.


5. If it takes you fewer than 5 minutes to fall asleep at night, you're probably sleep-deprived. Ideally, falling asleep should take 10 to 15 minutes.


6. Today, 75 percent of us dreams in color. Before color television, only 15 percent of us did.


7. More than one half (59 percent) of Americans reported getting less sleep on weekdays than on weekends.


8. Obstructive sleep apnea syndrome acquired its name from a character in The Posthumous Papers of the Pickwick Club by Charles Dickens. It's no surprise, therefore, that the condition is also called "Pickwickian sydrome."



9. English Bulldogs are the only canines believed to suffer from sleep apnea. Their short snouts and under-bites, which make for an unusual airway anatomy, is likely the reason.


10. Elephants and giraffes sleep for as little as three to four hours in a 24-hour period.


11. Snails can sleep for three years.


12. Men sleep better beside their mate, while women sleep worse.


13. Babies begin to yawn in the womb. They also spend much of their time in REM sleep, the stage in which dreams occur.


14. Parents of newborn babies miss out on six months' worth of sleep in the first two years of their child's life. Ouch.


15. Women are more likely to suffer from insomnia than men.


16. The brains of deep sleepers who seem impervious to noise have a distinctive brain pattern on an EEG.


17. A study published in the British Medical Journal demonstrated that sleep-deprived people appear less healthy, less attractive and more tired compared with when they are well rested, thus adding some credence to the idea of "getting your beauty sleep."


18. In a pack of sleeping ducks, the ones on the outside will sleep with only half their brains so they can keep watch for the rest. Dolphins, whales and penguins are also known to have the ability to put half their brain to sleep.


19. Sea otters hold hands when they sleep so they don't drift away from each other.


20. We naturally feel tired at two different times of the day: about 2 a.m. and 2 p.m. It is this natural dip in alertness that is primarily responsible for the post-lunch dip.


21. Snoring is the primary cause of sleep disruption for approximately 90 million American adults; 37 million on a regular basis.


22. People who don't get enough sleep are more likely to have bigger appetites due to the fact that their leptin levels (leptin is an appetite-regulating hormone) fall, promoting appetite increase. How's that for unfair?


23. Scientists still don't know for sure if animals dream during REM sleep, as humans do.


24. Our bodies never adjust to shift work.


25. Trying to catch some Z's on the plane for your third business trip in two months? Bad news: the higher the altitude, the greater the sleep disruption. Generally, sleep disturbance becomes greater at altitudes of 13,200 feet or more. The disturbance is thought to be caused by diminished oxygen levels and accompanying changes in respiration. Most people adjust to new altitudes in approximately two to three weeks.


26. Sleeping fewer than 7 hours a night is believed to reduce your life expectancy. Gulp.


27. It is physically impossible to sneeze while you are sleeping.


28. You burn more calories sleeping than you do sitting on the couch watching television.


29. If you're finding it difficult to get up in the morning, it may be a condition called "dysania." It may signal a nutritional deficiency, depression or other problems.


30. Being awake for 16 hours straight decreases your performance as much as if your blood alcohol level were .05 percent. The legal limit is .08 percent, for comparison.


31. Although exercising regularly makes it easier to fall asleep and is believed to contribute to sounder sleep, doing so sporadically or right before going to bed will make falling asleep more difficult.



Centers for Disease Control and Prevention

Cleveland Clinic: HealthHub

Health Sleep, a resource from the Division of Sleep Medicine at Harvard Medical School produced in partnership with WGBH Educational Foundation

NCBI: US National Library of Medicine National Institutes of Health

National Sleep Foundation