Tuesday, March 20, 2007

Sleep deprivation

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Sleep deprivation is a general lack of the necessary amount of sleep. A person can be deprived of sleep by their own body and mind, as a consequence of some sleep disorders, or, actively, by another individual. Sleep deprivation is sometimes employed as an instrument of interrogation. It has been reported that sleep deprivation affects tens of millions of adults each year.[1].



[edit] Effects of Sleep Deprivation

Lack of sleep may result in[2][3][4][5][6][7][8][9]:

[edit] As a cause of Diabetes

A 1999 study by the University of Chicago Medical Center shows that sleep deprivation severely affects the human body's ability to metabolize glucose, which can lead to early-stage Diabetes Type 2.[10]

[edit] Effects on the brain

Sleep deprivation can adversely affect brain function.[9]A 2000 study by the UCSD School of Medicine and the Veterans Affairs Healthcare System in San Diego, used functional magnetic resonance imaging (fMRI) technology to monitor activity in the brains of sleep-deprived subjects performing simple verbal learning tasks.[11] The study showed that regions of the brain's prefrontal cortex (PFC) displayed more activity in sleepier subjects. Depending on the task at hand, in some cases the brain attempts to compensate for the adverse effects caused by lack of sleep. The temporal lobe, which is a brain region involved in language processing, was activated during verbal learning in rested subjects but not in sleep deprived subjects. The parietal lobe, not activated in rested subjects during the verbal exercise, was more active when the subjects were deprived of sleep. Although memory performance was less efficient with sleep deprivation, greater activity in the parietal region was associated with better memory.

Animal studies suggest that sleep deprivation increases stress hormones, which may reduce new cell production in adult brains.[12]

[edit] Effects on growth

According to a 1999 study[13]:

Sleep deprivation results in a significant reduction of cortisol secretion the next day and this reduction appears to be, to a large extent, driven by the increase of slow wave sleep during the recovery night. Deep sleep has an inhibitory effect on the HPA [Hypothalmic-pituitary] axis while it enhances the activity of the GH [growth hormone] axis. In contrast, sleep disturbance has a stimulatory effect on the HPA axis and a suppressive effect on the GH axis. These results are consistent with the observed hypocortisolism in idiopathic hypersomnia and HPA axis relative activation in chronic insomnia. Finally, our findings support previous hypotheses about the restitution and immunoenhancement role of slow wave (deep) sleep.

[edit] Impairment of ability

According to a 2000 study published in the British scientific journal, researchers in Australia and New Zealand reported that sleep deprivation can have some of the same hazardous effects as being drunk.[14][15] People who drove after being awake for 17–19 hours performed worse than those with a blood alcohol level of .05 percent, which is the legal limit for drunk driving in most western European countries (the U.S. set their blood alcohol limits at .08 percent). In addition, as a result on continuous muscular activity without proper rest time, effects such as cramping are much more frequent in sleep-deprived individuals. Extreme cases of sleep deprivation have been reported to be associated with hernias, muscle fascia tears, and other such problems commonly associated with physical overexertion. Beyond impaired motor skills, people who get too little sleep may have higher levels of stress, anxiety and depression, and may take unnecessary risks. According to the National Highway Traffic Safety Administration, over 100,000 traffic accidents each year are caused by fatigue and drowsiness.[16][17] A new study has shown that while total sleep deprivation for one night caused many errors, the errors were not significant until after the second night of total sleep deprivation.[18]

[edit] As a cause of obesity

Several large studies using nationally representative samples suggest that the obesity epidemic in Europe and the United States might have as one of its causes a corresponding decrease in the average number of hours that people are sleeping.[19][20][21] The findings suggests that this might be happening because sleep deprivation might be disrupting hormones that regulate glucose metabolism and appetite.[22] The association between sleep deprivation and obesity appears to be strongest in young and middle-age adults. Other scientists hold that the physical discomfort of obesity and related problems, such as sleep apnea, reduce an individual's chances of getting a good night's sleep.

[edit] As a scientific method

In science, sleep deprivation (of rodents, e.g.) is used in order to study the function(s) of sleep and the biological mechanisms underlying the effects of sleep deprivation.

Here are some sleep deprivation techniques:

  • gentle handling (often require polysomnography): during the sleep deprivation period, the animal and its polygraph record are continuously observed; when the animal displays sleep electrophysiological signals or assumes a sleep posture, it is given objects to play with and activated by acoustic and if necessary tactile stimuli (see Franken, 1991). Although subjective (see e.g. Rechtschaffen, 1999), this technique is used for total sleep deprivation as well as REM or NREM sleep deprivation.
Rodent sleep deprivation by the single platform ("flower pot") technique
Rodent sleep deprivation by the single platform ("flower pot") technique
  • single platform: probably one of the first scientific methods (see Jouvet, 1964 for cats and Cohen, 1965 for rodents). During the sleep deprivation period, the animal is placed on an inverted flower pot whose bottom diameter is relative to the animal size (usually 7 cm for adult rats); the pot is placed in a large tub filled with water to within 1 cm of the flower pot bottom. The animal is able to rest on the pot and is even able to get NREM sleep. But at the onset of REM sleep, with its ensuing muscular relaxation, it would either fall into the water and clamber back to its pot or would get its nose wet enough to awake it. So this technique is used only for REM sleep deprivation.
  • multiple platform: in order to reduce the elevated stress response induced by the single platform method, Van Hulzen and Coenen (1981) developed this technique in which the animal is placed into a large tank containing multiple platforms, thus eliminating the movement restriction experienced in the single platform. This technique is also used only for REM sleep deprivation.
  • modified multiple platform: modification of the multiple platform method where several animals together get the sleep deprivation (Nunes and Tufik, 1994).
  • pendulum: animals are prevented from entering into PS by allowing them to sleep for only brief periods of time. This is accomplished by an apparatus which moves the animals' cages backwards and forwards like a pendulum. At the extremes of the motion postural imbalance is produced in the animals forcing them to walk downwards to the other side of their cages (Van Hulzen, 1980).

[edit] As a form of torture

Sleep deprivation is considered by some to be torture. It has been used as a way of interrogating suspected political opponents (for example, in Pinochet-era Chile).[23] Interrogation victims are kept awake for several days, then when they are finally allowed to fall asleep, suddenly awakened and questioned. However, this is a controversial issue.[24][25] Nicole Bieske, a spokeswoman for Amnesty International Australia, has stated, "At the very least, [sleep deprivation] is cruel, inhumane and degrading. If used for prolonged periods of time it is torture."[23]

[edit] As a treatment for depression

Recent studies show sleep deprivation has some potential in the treatment of depression. About 60% of patients, when sleep-deprived, show immediate recovery, with most relapsing the following night. The incidence of relapse can be decreased by combining sleep deprivation with medication [26]. Incidentally, many tricyclic antidepressants happen to suppress REM sleep, providing additional evidence for a link between mood and sleep [27]

[edit] Sleep deprivation and school

In the United States sleep deprivation is common with students due to the fact that almost all schools begin early in the morning, forcing students to get less sleep than they normally would.[28] Because of this, their grades go down and their concentration is impaired, and students, who should be getting between 8.5 and 9.25 hours of sleep[citation needed], are getting only 7 hours due to the strict school policies.[28]In most studies, the issues of parental responsibility over their children's lifestyle was not introduced. In several school districts, the opening of school was delayed by over an hour to give students more sleep. For example, in 1997 the University of Minnesota did research that compared students who went to school at 7:15 and those who went to school at 8:40. They found that students who went to school at 8:40 got higher grades and more sleep on the weekdays.[16][29] The National Sleep Foundation did a survey and found that students get an average of 6.8 hours of sleep, which is far below the amount needed.[30] Students get more sleep in the summer than during the school year.[31] One in four US high school students admit to falling asleep in class at least once a week.[32]

[edit] Prevention of effects in soldiers

Since sleep deprivation is a fact of modern combat, the U.S. Army, through DARPA, has a "Preventing Sleep Deprivation Program", which has the goal to prevent the harmful effects of sleep deprivation and provide methods for recovery of function with particular emphasis on cognitive and psychomotor impairments. Their efforts include new pharmaceuticals that enhance neural transmission, nutraceuticals that promote neurogenesis, cognitive training, and devices such as transcranial magnetic stimulation.

The United States military has recently begun to explore the use of a new drug called Modafinil, which has prevented the negative effects of sleep deprivation in soldiers. Modafinil may increase wakefulness through activation of noradrenergic and dopaminergic systems, possibly through interaction with the hypocretin/orexin system PMID 15532213.

[edit] See also

[edit] References

  1. ^ "http://library.cqpress.com/cqresearcher/ppv.php?id=cqresrre1998062600".
  2. ^ "http://www.betterhealth.vic.gov.au/bhcv2/bhcarticles.nsf/pages/Sleep_deprivation?OpenDocument".
  3. ^ "http://www.apa.org/ed/topss/bryanread.html".
  4. ^ "http://www.lucidnet.co.uk/sleep/disorders/deprivation.htm".
  5. ^ "http://www.postgradmed.com/issues/2002/10_02/pn_sleep.htm".
  6. ^ "http://www.vineland.org/mennies/sleep_trouble_in_school.htm".
  7. ^ "http://www.health.harvard.edu/press_releases/sleep_deprivation_problem.htm".
  8. ^ "http://www.jiskha.com/health/social_health/sleep_deprivation.html".
  9. ^ a b "http://www.fi.edu/brain/sleep.htm".
  10. ^ "Daniel J. Gottlieb, et al. Association of Sleep Time With Diabetes Mellitus and Impaired Glucose Tolerance. Arch Intern Med. Vol. 165 No. 8 2005; 165: 863-867 PMID 15851636.".
  11. ^ "http://health.ucsd.edu/news/2000_02_09_Sleep.html".
  12. ^ http://news.bbc.co.uk/2/hi/health/6347043.stm
  13. ^ "Alexandros N. Vgontzas, George Mastorakos, Edward O. Bixler, Anthony Kales, Philip W. Gold & George P. Chrousos, published in Clinical Endocrinology, Volume 51 Issue 2 Page 205, August 1999".
  14. ^ "http://oem.bmjjournals.com/cgi/content/abstract/57/10/649".
  15. ^ "http://oem.bmjjournals.com/ Occupational and Environmental Medicine".
  16. ^ a b "http://www.apa.org/monitor/oct01/sleepteen.html".
  17. ^ "http://www.holyname.org/healthcare/excellence/njnsleep/sleep_deprivation.htm".
  18. ^ Journal of Sleep Research "Effects of two nights sleep deprivation and two nights recovery sleep on response inhibition".
  19. ^ Does the lack of sleep make you fat?, Bristol University Press Release, December 7, 2004
  20. ^ The association between short sleep duration and obesity in young adults: a 13-year prospective study., Sleep, Jun 15;27(4):661-6 2004
  21. ^ Inadequate sleep as a risk factor for obesity: analyses of the NHANES I, Oct 1;28(10):1289-96 2005
  22. ^ Sleep as a mediator of the relationship between socioeconomic status and health: a hypothesis, Ann N Y Acad Sci., 896:254-61 1999
  23. ^ a b "http://www.smh.com.au/news/National/Sleep-deprivation-is-torture-Amnesty/2006/10/03/1159641317450.html".
  24. ^ "http://www.abc.net.au/pm/content/2006/s1754821.htm".
  25. ^ "http://au.news.yahoo.com/061003/21/10rum.html".
  26. ^ "http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=10459393&dopt=Abstract".
  27. ^ "http://www.emedicinehealth.com/articles/42677-5.asp".
  28. ^ a b "http://sleepdisorders.about.com/cs/sleepdeprivation/a/backtoschool.htm".
  29. ^ "http://www.nysut.org/research/bulletins/981202adolescentsleep.html".
  30. ^ "http://sleepdisorders.about.com/cs/sleepdeprivation/a/depstudents.htm".
  31. ^ "http://www.healthysleeping.com/focus_article.asp?f=sleep_disorders&c=sleep_backtoschool&b=healthysleeping&spg=SHO".
  32. ^ "http://abcnews.go.com/US/wireStory?id=1775003".

[edit] External links

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