Just to be clear, I do not mean sleeping with someone. I mean sleeping – as in dozing off, like siesta or ‘playing dead.’If you are 30 years old, you have spent 10 of those years asleep and if you are 60, it means you slept for the equivalent of ‘from the day your child was born’ to waking up and finding him at the very end of his teen years. We spend a third of our time asleep.
In some societies, sleeping, especially during the day, is associated with laziness but did you know that 17 hours of sustained wakefulness leads to a decrease in performance equivalent to a blood alcohol-level of 0.05 percent, which, in the UK at least, is the legal drink driving limit?
Why do we need to sleep at all? Have you ever wondered why?
Napoleon and Florence Nightingale slept for an average of only four hours a night while Thomas Edison considered sleeping “a waste of time.”
Ironically, it was Edison’s invention, the light-bulb that ‘revolutionalised’ sleeping habits and drastically shortened the time spent in bed.
“Today, average young adults report sleeping about seven to less than eight hours each night, “ says The Psychiatric Times. “Compare this to sleep patterns in 1910, before the electric light bulb. The average person slept nine hours each night. This means (says Webb & Agnew, 1975) that today’s population sleeps one to two hours less than people did early in the last century.”
Because of the advent of the light bulb, people sleep 500 hours less each year than they used to.
Apparently ‘sleep is one of those funny things about being a human being ÔÇö you just have to do it.’
Most of what we know about sleep we’ve learned in the past 25 years.
“Despite decades of intense research,” says an on-line medical information site, “scientists still have only clues about sleep function. Because sleep is heterogeneous, there are various theories none of which predominates.”
The BBC says that the question why we sleep has baffled scientists for centuries and the answer is: no one is really sure.
“Some,” says Science & Nature Magazine, “believe that sleep gives the body a chance to recuperate from the day’s activities but in reality, the amount of energy saved by sleeping for even eight hours is miniscule – about 50 kCal, the same amount of energy in a piece of toast.”
An on-line information center says sleep is generally characterized by a reduction in voluntary body movement, temporary blindness, decreased reaction to external stimuli, loss of consciousness, a 70 percent reduction in audio receptivity, an increased rate of anabolism (the breakdown of cell structures).
Ironically, instead of scientists explaining why we need to sleep, they find it easier to tell us what happens when we don’t sleep.
“Recent research suggests that each day with insufficient sleep increases our sleep debt and, when this sleep debt becomes large enough, noticeable problems appear. These sleep-debt-related problems are most predictable at certain times of the day. This is because the efficiency of our physical and mental functions shows cyclic increases and decreases in the form of circadian rhythms. While our major sleep/wakefulness rhythm has a cycle length of roughly 24 hours, there are shorter cycles as well, with the most important of these being a secondary sleep/wakefulness cycle that is around 12 hours.
“Because of these cycles, the pressure to fall asleep is greatest in the morning, between 1 and 4 a.m. In addition there is a less pronounced, but still noticeable, increase in sleepiness 12 hours later, between 1 and 4 p.m. It is this afternoon low point that makes you feel sleepy after lunch, not the meal that you may have just eaten. It probably also was the original reason for the afternoon nap or siesta.”
But what would happen if we did not sleep?
In 1965, a Randy Gardner set a world record for the longest period without sleep. For 11 days, Randy Gardner went without sleep.
“He experienced significant deficits in concentration, motivation, perception and other higher mental processes during his sleep deprivation,” says Wikipedia. “However, he recovered normal cognitive functions after a few nights’ sleep.”
The BBC’s on-line Science & Nature Magazine says four days into the research, Gardner began hallucinating.
“This was followed by a delusion where he thought he was a famous footballer. Surprisingly, Gardner was actually functioning quite well at the end of his research and he could still beat the scientist at pinball.”
A good way to understand the role of sleep is to look at what would happen if we didn’t sleep.
“Lack of sleep has serious effects on our brain’s ability to function,” says Science & Nature. “The effects include grumpiness, grogginess, irritability and forgetfulness. After just one night without sleep, concentration becomes more difficult and attention span shortens considerably.”
With continued lack of sufficient sleep, it continues, the part of the brain that controls language, memory, planning and sense of time is severely affected, practically shutting down.
In real life situations, the consequences of sleep deprivation are grave.
“Lack of sleep is said to have been a contributory factor to a number of international disasters such as the 1989 Exxon Valdez oil spill off Alaska, the Challenger space shuttle disaster, the Three Mile Island nuclear debacle and the Chernobyl nuclear accident.”
All have been attributed to human errors in which sleep-deprivation played a role.
Sleep deprivation, continues Science & Nature, not only has a major impact on cognitive functioning but also on emotional and physical health.
Disorders such as sleep apnea, which result in excessive daytime sleepiness, have been linked to stress and high blood pressure.
“Research has also suggested that sleep loss may increase the risk of obesity because chemicals and hormones that play a key role in controlling appetite and weight gain are released during sleep.”
Sleep occurs in a recurring cycle of 90 to 110 minutes. During the first stage of sleep, we’re half awake and half asleep. Our muscle activity slows down and slight twitching may occur. This is a period of light sleep, meaning we can be awakened easily at this stage.
Within ten minutes of light sleep, we enter stage two, which lasts around 20 minutes. This is true sleep. The breathing pattern and heart rate start to slow down. This period accounts for the largest part of human sleep.
Deep sleep occurs during stage three. The brain begins to produce delta waves, a type of wave that is large (high amplitude) and slow (low frequency). Breathing and heart rate are at their lowest levels.
Researchers say that stage four is characterised by rhythmic breathing and limited muscle activity. If we are awakened during deep sleep, we do not adjust immediately and often feel groggy and disoriented for several minutes after waking up. Some children experience bed-wetting, night terrors, or sleepwalking during this stage.
“Although we are not conscious, the brain is very active – often more so than when we are awake,” Science and Nature says. “This is the period when most dreams occur. Our eyes dart around (hence the name Rapid Eye Movement (REM)), our breathing rate and blood pressure rise. However, our bodies are effectively paralysed, said to be nature’s way of preventing us from acting out our dreams.”
Growth hormone in children is secreted during sleep, and chemicals important to the immune system are secreted during sleep. You can become more prone to disease if you don’t get enough sleep, and a child’s growth can be stunted by sleep deprivation.
But just how much sleep do we need? Scientists say there is no set amount of time that everyone needs to sleep, since it varies from person to person. People like to sleep anywhere between 5 and 11 hours, with the average being 7.75 hours.
Jim Horne from Loughborough University’s Sleep Research Centre has a simple answer though: “The amount of sleep we require is what we need not to be sleepy in the daytime.”
A python sleeps for 18 hours a day while the African elephant and the giraffe sleep for only 3.3 hours and 1.9 hours a day, respectively. Cattle, horses, and sheep can sleep while standing or while lying down; but they only dream if they lie down. Whales and dolphins are “conscious breathers” (they have to be awake to breath) and they need to keep breathing while they sleep, so only one half of the brain sleeps at a time.
Teenagers need as much sleep as small children (about 10 hrs) while those over 65 need the least of all (about six hours). For the average adult aged 25-55, eight hours is considered optimal
Some studies suggest women need up to an hour’s extra sleep a night compared to men, and not getting it may be one reason women are much more susceptible to depression than men.
Nite, nite! Don’t let the bed bugs bite!