Wonders of Sleep

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One boring and sleepy afternoon, while I was reviewing and interpreting sleep studies, which are 6 to 8 hour-long tracings and video of a patient’s sleep data, a reflective thought came upon me. I came a long long way from the boy who got intrigued with the mystery of sleep. I never imagine at that time that I will earn a living by watching people sleep. I can also claim that I interpret people’s sleep info, though not necessarily their dreams.

I love sleep. I don’t mean that I love to sleep (though that may be true sometimes), but the science of sleep. Long before I became a sleep specialist, I was always fascinated with the phenomenon of sleep. I admit though that as a little boy I hate taking naps, and I would often sneak out of my room during afternoons when my mother told me to do so.

When I was in grade school, I clipped and collected Johnny Wonder’s strips about scientific facts of sleep from a newspaper cartoon section. So long before the rock band REM became popular during my college days, I already knew what REM means, that is rapid eye movement, which is a stage of sleep, and is probably the most intriguing phase of our sleep.

In highschool, I wondered if people can hear and learn things while they are sleeping. So I did an experiment. I recorded myself reading my world history book. Then I played back the tape while I was sleeping, and determine how much facts I will retain for our test the next day. The result? I passed the test! Maybe it was the reading that helped me remember the facts and not necessarily that I learned something while I was sleeping. However a recent study from Israel showed that people can really learn new information while they are sleeping.

new way of learning?

The phenomenon of sleep is not something to snore about, for it is really an interesting science. Here are some amazing facts about sleep.

1. A human can last longer without food, than without sleep. Because at some point after several hours or days of continued wakefulness or sleep deprivation, a person will involuntarily fall asleep even how much he fights it. The record for longest period without sleep is 18 days, 21 hours, and 40 minutes during a rocking chair marathon. But a human can survive more than a month without food, though with water.

2. All mammals sleep. All birds, many reptiles, amphibians, and fish too. Humans sleep on average around three hours less than other primates like chimps, rhesus monkeys, and baboons, all of whom sleep for 10 hours. A giraffe sleeps an average of less than 2 hours per day. (And they still grow so tall!) Though some people try to be giraffes! Adult humans need 7-9 hours of sleep a day to function properly. Newborns needs up to 18 hours, while toddlers and school children require 10 hours and more.

3. Anything less than 5 minutes to fall asleep at night means that you are sleep deprived. The normal sleep latency is between 10 and 15 minutes. So if you’re falling asleep the moment you hit the pillow or faster than you can recite the alphabet, that is a telltale sign that something is amiss. Other signs of sleep deprivation includes  decreased performance, alertness, and memory and cognitive impairment.

4. During the REM phase of sleep, is when we dream dreams that we can vividly recall. Dreams though can also occur in non-REM phase of sleep. REM sleep occurs in bursts totalling about 2 hours a night, usually beginning about 90 minutes after falling asleep. It is thought that REM consolidates certain memories. It is also believed to help developing brain mature. Premature babies can have 75% REM phase, while a normal adult has an average of 20-25 % REM phase of his total sleep time. Life will be dull if you’re deprived of REM, because you won’t have much dreams! Unfortunately most of the sleeping pills used can actually suppress REM phase of sleep.

5. It is impossible to tell if someone is really awake without close supervision. People can take cat naps with their eyes open without even being aware of it. We use electroencephalogram (EEG) to determine if a person have fallen asleep and to determine the stage of their sleep, when we perform sleep studies. Some students are good example of this, sitting in a lecture hall with eyes wide open but are really sleeping. Especially after they stay up late partying the night before. But then again some people really go through life fast asleep, figuratively speaking.

Have a goodnight, sleep tight, and pleasant dreams to you.

(*photo from here)

(**some facts are taken from National Sleep Research Project)


  1. I love my sleep and I can be an intolerable bear when I can’t get enough of it. This tends to happen when I have to travel for work or even just long flights. Like the one we just took from SFO to Rome. It was brutal.

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