Реферат: Sleep And Sleep Deprivation Essay Research Paper

Sleep And Sleep Deprivation Essay, Research Paper


Research paper

Sleep and sleep deprivation

Sleep and Sleep Deprivation

October 1999, the movie Fight Club was released. The story was about a man that suffered from intense insomnia 4 months of consecutive wakefulness.


Sleep is the biological process that a person spends almost a third of their life doing. After decades of research, we still cannot say we have a full understanding of this process. One thing that is safe to say is that it has a function; considering the large amount of time that organisms spend on it, if it was not adaptive, it would not survive through evolution. As for what kind of function it serves, there is still no definite answer (Pinel 1999 [Rechtschaffan 1998]). But there are two main theories that are trying to explain what we do know so far.

The first theory is the Recuperation Theory, which is the way most people perceive and explain sleep. It sees sleep as a repairing process that reverses the imbalance of our system caused by daily activity. It assumes that activities during our wakefulness disturbs our body s homeostasis. The common concept of needing more sleep to catch up previously lost sleep would belong to this theory.

The second theory is the Circadian Theory. It explains that sleep is just a way for animals to conserve energy and to avoid unnecessary activities. It also focuses on circadian rhythms (Pinel 1999 [Hastings, 1997]), which are the cycles an animal follows for sleeping and waking, with each cycle lasting about 24 hours. According to Groos, 1983, it is virtually impossible to find a physiological, biochemical or behavioral process in animals which does not display some measure of circadian rhythmicity. And in order for our circadian cycles to be synchronized with the 24 hour day, we rely on zeitgebers, environmental cues, to adjust our cycles.

Even though the recuperation theory is more widely acknowledged, it seems the circadian theory explains more of the picture. For example, the recuperation theory would predict sleep deprivation would cause serious physiological dysfunction, but research shows that is not the case (Pinel 1999 [Karadzic 1973, Horne 1983 and Martin 1986]). But of course there is research that challenges the circadian theory as well. REM (rapid eye movement) sleep deprivation has been reported to lead to various personality and motivation problems (Pinel 1999 [Dement 1960]) and also memory deficits for certain learning processes (Pinel 1999 [Karni et al. 1994]), which would be against the circadian belief.

Sleep deprivation

Now that we have talked about sleeping, we can discuss what happens when we do not get enough of it.

Self-sleep deprived teenagers and dosing drivers are issues that we focus on decade after decade. We should be fairly educated in sleep deprivation and it s effects. But after looking at the research done so far, it seems that our common sense in sleep deprivation was not very scientific after all.

Some of the findings are controversial, but so far there are a few conclusions we can make about sleep deprivation.

As mentioned before, sleep deprivation can lead to a variety of personal and motivation problems, and memory deficits of certain material. Other effects of sleep deprivation are impairment of innovative thinking and flexible decision making (Binks, Waters & Hurry 1999), poor performance on vigilance tasks (Pinel 1999 [Gillberg et al. 1996]) and increase of sleepiness and microsleeps. Even though sleep-deprived people often report feeling tired and emotionally disturbed, and they do perform poorly on passive cognitive tasks, but many of the negative effects of sleep deprivation are confounded by other factors such as stress and circadian disruptions (Pinel 1999). Since these other factors could well contribute to negative effects, and in fact they were the cause the people loss sleep in the first place, we cannot consider these personal experiences as effects of sleep deprivation alone.

Another reason why negative effects of sleep deprivation are exaggerated is due to the effect of microsleeps. A person s cognitive abilities for demanding tasks like abstract reasoning and spatial relations are not effected even after one night of sleep deprivation (Percival, Horne & Tilley 1983), but in fact when faced with less demanding tasks like driving, a person would easily drift into microsleeps, thus leading to serious problems. It has also been reported that even for sleep deprivation up to 72 hours, there was no effect on strength or motor performance, except for reducing the time to exhaustion (Van Helder & Radomski 1989).

What is interesting is that there is no correlation between the magnitude of performance deficits and the amount of sleep deprivation, in fact, according to Pilcher and Huffcutt (1996), effects of partial sleep deprivation have been reported to be greater than those of total sleep deprivation (even up to several days).

After learning that the negative effects of sleep deprivation are not as drastic as the media presents it, once again question Do we need all of the sleep we usually get, or is some of it just wasted time? is raised.

Speculation towards sleep reduction

Do you notice when people seek ways to live longer, they are usually looking at how to delay death? But since we never know what will happen to us after today, attempts to delay death don t seem to help much in terms of a more efficient life. Instead, what if we could reduce our sleep, making more time for each day? This extra time could be managed toward productivity. I sleep about 8 hours a day, if I lived to 70, I would have spent more than 23 of those years asleep. Can you imagine how big a difference sleep reduction could make?

There are two studies that looked at long term sleep reduction. The first one is Webb & Agnew s (1974) in which a group of 16 participants reduced their sleep to 5.5 hours per night for 60 days. Only one deficit was reported, on an extensive battery of mood, medical and performance test, which was a slight deficit of auditory vigilance (Pinel 1999).

The second study was done my Friedman & Mullaney 1977, in which 8 participants systematically reduced their sleep bit by bit over a year s time, until each of then reached a minimum of sleep they preferred, and were asked to maintain that minimum sleep lever for a month. Out of the 8 participants, the minimum for 2 of them was 5.5 hours, for 4 of them it was 5 hours and 4.5 hours for the other 2. Even though each of them did experience sleepiness, which became worse as further reduction continued, nevertheless, no mood deficits, health problems or effects on performance tests were found. And a year after the study, the follow-up reported that the subjects were sleeping less than they were before the study (between 7-18 hours less each week) with no excessive sleepiness (Pinel 1999).

There have also been studies of polyphasic sleep sleeping many times each day for short duration instead of a long, continuous sleep, inspirited by the legend of Leonardo da Vinci, of how he napped 15 minutes each 4 hours each day. Surprisingly this legend was replicable (Stampi 1992); which suggested that if the efficiency of sleep is raised, the amount can be reduced with minor side effects.

Before preparing for this report, I was never aware that such sleep reduction was possible, thinking that my regular 8 hours were optimal for my well being. It makes me wonder why there is not more research or publication on it. I think the realm of sleep is fascinating and definitely worth more attention.

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