Microsleep are often the cause of short term memory deficits, occur at any time, typically without significant warning & Drivers were totally unaware of it
Micro-sleep is descried as a brief, unintentional episode of loss of attention associated with a blank stare, head snapping and prolonged eye closure that lasts from 2 to 30 seconds, also known as "nodding off”.
From Wikipedia, the free encyclopedia
A microsleep is an episode of sleep which may last for a fraction of a second or up to thirty seconds. It often occurs as a result of sleep deprivation, or mental fatigue, sleep apnea, hypoxia, narcolepsy, or hypersomnia.
Microsleeps can occur at any time, typically without significant warning. In the middle of even lively conversations, the onset of a microsleep episode can cause sufferers to 'suddenly' lose the thread of a conversation.
Microsleeps (or microsleep episodes) become extremely dangerous when occurring during situations which demand continual alertness, such as driving or working with heavy machinery. People who experience microsleeps usually remain unaware of them, instead believing themselves to have been awake the whole time, or feeling a sensation of 'spacing out'.
One example is called "gap driving": from the perspective of the driver, he or she drives a car, and then suddenly realizes that several seconds have passed by unnoticed. It is not obvious to the driver that he was asleep during those missing seconds, although this is in fact what happened. The sleeping driver is at very high risk for having an accident during a microsleep episode.
Many accidents and catastrophies have resulted from microsleep episodes in these circumstances.For example, a microsleep episode is claimed to have been one factor contributing to the Waterfall train disaster in 2003; the driver had a heart attack and the guard who should have reacted to the train's increasing speed is said by his defender to have microslept.
There is little agreement on how best to identify microsleep episodes. Some experts define microsleep according to behavioral criteria (head nods, drooping eyelids, etc.), while others rely on EEG markers. One study at the University of Iowa defined EEG-monitored microsleeps in driving simulation as "a 3-14 second episode during which 4-7 Hz (theta) activity replaced the waking 8-13 Hz (alpha) background rhythm."
References
- ^ International Classification of Sleep Disorders Diagnostic and Coding Manual
- ^ Blaivas AJ, Patel R, Hom D, Antigua K, Ashtyani H (2007). "Quantifying microsleep to help assess subjective sleepiness". Sleep Med. 8 (2): 156–9. doi:10.1016/j.sleep.2006.06.011. PMID 17239659. http://linkinghub.elsevier.com/retrieve/pii/S1389-9457(06)00197-3.
- ^ Paul, Amit; Linda Ng Boyle, Jon Tippin, Matthew Rizzo (2005). "Variability of driving performance during microsleeps" (PDF). Proceedings of the Third International Driving Symposium on Human Factors in Driver Assessment, Training and Vehicle Design. http://ppc.uiowa.edu/driving-assessment/2005/final/papers/04_AmitPaul_LBoyleformat.pdf. Retrieved on 2008-02-10.
- (PMID 12530990) Ogilvie RD. The process of falling asleep. Sleep Med Rev 5: 247-270, 2001
- PMID 14592362 Microsleep and sleepiness: a comparison of multiple sleep latency test and scoring of microsleep as a diagnostic test for excessive daytime sleepiness. 2003
- PMID 15320529 Microsleep from the electro- and psychophysiological point of view. 2003
Detail Definition
A phenomenon usually associated with the effects of sleep deprivation. They are very short periods of sleep (measured in seconds), of which the person experiencing them may not even be aware.
If you have seen someone doing the uncontrollable head nod in a lecture, you're watching someone who is rapidly going beyond the mere microsleep, and is now fully intent on sleeping while sitting. If you are experiencing that 'I can't keep my eyes open' feeling, and you failed to do so, congratulations: you just had a microsleep.
It's my presumption that many single vehicle accidents result from microsleeps. You don't really need to fall fully asleep to find a tree; a couple of seconds can do it. Do not drive while sleep deprived on a regular basis, as it is comparable to driving under the influence of drugs. In fact, it is really the same thing, they're just your own personal internally released sedatives (as well as brain activity supression, but that's for the neuropsychologists).
Microsleeps are often the cause of short term memory deficits, increased reaction times, and generally poorer task performance associated with sleep deprivation, since presented stimuli may not actually be registered by the subject during a microsleep. The same mechanism can also explain some longer term effects on memory (but it is not the only agent).
Do you suffer from the sleep disorder called "micro-sleep"?
Micro-sleep is descried as a brief, unintentional episode of loss of attention associated with a blank stare, head snapping and prolonged eye closure that lasts from 2 to 30 seconds, also known as "nodding off,”
Because one of the symptoms of fatigue is the decreased ability to judge your own level of tiredness, a typical response is to fight fatigue and try to stay awake. When a fatigued person is trying to stay awake in order to perform a monotonous task such as driving, microsleeps are likely to occur.
A microsleep is a brief, unintentional episode of loss of attention associated with events such as a blank stare, head snapping and prolonged eye closure. A microsleep is also known as “nodding off”. Microsleeps are unintended periods of light sleep that typically last between 2 and 30 seconds.
A person may not be aware that a microsleep has occurred. In fact, microsleeps often occur when a person's eyes are open. While in a microsleep, a person fails to respond to outside information. If this occurs while driving, you may not see a red traffic signal, notice that the road has taken a curve or the traffic lanes are narrowing.
§ The most important thing to know about Driver Fatigue is that it is a silent killer. It is the experience of being ‘sleepy’, ‘tired’ or ‘exhausted’ whilst driving a vehicle.
§ You may demonstrate a number of symptoms of fatigue well before you actually feel the compelling need to shut your eyes. These symptoms may include restlessness, reaching for the lollies more often, irritability or boredom. Don’t ignore these early warning signs. This is the time to pull over and take a break.
§ Driver Fatigue is a physiological and psychological experience that can severely impair driver judgement and can affect any motorist at any time.
§ Yawning, stretching, keeping the window open, drinking caffeinated drinks, or turning up the music may make you feel better temporarily, but only sleep can fix fatigue.
Some signs of Driver Fatigue may include:
§ Yawning
§ Restlessness
§ Heavy or sore eyes
§ Blurred vision
§ Slowed reactions
§ Poor concentration
§ Impatience
§ Not remembering the last few kilometres of your trip
§ Microsleeps
§ Driver Fatigue is a major factor in up to 20% of the annual road toll throughout world.
§ Although the majority of fatigued drivers involved in fatal crashes are males, fatigue can affect any driver.
§ The risk of a fatal fatigue crash is highest between 10pm and 6am when your body’s circadian rhythms are programming you to sleep - four times greater than for the rest of the day.
§ Driving while sleep deprived, especially late at night and at dawn increases the risk of having a microsleep and losing control of your vehicle. A microsleep is a brief and unintended loss of consciousness.
§ During a 4 second microsleep a car travelling at 100km/hr will travel 111metres while completely out of the drivers control.
§ Plan your rest breaks and overnight accommodation BEFORE you leave home;
§ Plan out your journey to ensure that you have plenty of rest stops – it is recommended that drivers take at least one rest stop every two hours;
§ If you are travelling with children, carry some of their favourite music, some puzzles, books, pencils and paper. Children can easily become bored so if possible plan some stops with facilities for the kids;
§ Get a good night’s sleep before commencing a long trip;
§ Eat light, fresh foods. Sandwiches and fruit are ideal snacks for drivers;
§ Avoid heavy, fatty foods, which hasten the onset of tiredness;
§ Try not to drive at times when you would normally be asleep;
§ Avoid long drives after work;
§ Take regular breaks from driving;
§ Share the driving wherever possible;
§ Pull over and stop when drowsiness, discomfort or loss of concentration occurs; and
§ Find out whether any medicine you are taking may affect your driving.
Waterfall rail accident
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(Redirected from Waterfall train disaster)
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| Waterfall rail accident | |
|
| |
| Details | |
| Date | 31 January 2003 |
| Time | 7:15 am |
| Location | |
| 37 km (23 mi) SW from Sydney | |
| Country | |
| Rail line | |
| Operator | |
| Type of incident | Derailment |
| Cause | Driver heart attack |
| Statistics | |
| Trains | 1 |
| Deaths | 7 |
The Waterfall rail accident was a train accident that occurred on 31 January 2003 near Waterfall, New South Wales, Australia. The train derailed killing seven people on board, including the train driver.[1]
Contents[hide] |
[edit] Incident
On the day of the disaster, a Tangara intercity train service, set G7, which had come from Central Station at 6:24 am, departed Waterfall railway station heading south towards Port Kembla Station via Wollongong. At approximately 7:15 am, the driver suddenly suffered a heart attack and lost control of the train. Consequently, the train was travelling at 117 km/h (73 mph) as it approached a curve in the tracks through a small gorge. This curve is rated for speeds up to 60 km/h (37 mph). The train derailed, overturned and collided with the rocky walls of the gorge in a remote area south of the station. It was reported that rescuers had to carry heavy lifting equipment for more than one and a half kilometres to reach the site.[2] Two of the carriages landed on their side and another two were severely damaged in the accident.[3] In addition to the seven fatalities, many more passengers were injured.
The subsequent official inquiry discovered the deadman's brake had not been applied. It was put forth by the train guard's solicitor that the guard was in a microsleep for up to 30 seconds just prior to the accident. The experienced human-factors accident investigator determined the organizational culture put the driver firmly in charge, making it psychologically more difficult for the guard to act. The guard in question had a history of not responding well to stress and refused to be interviewed by the investigator.
[edit] Causes of the accident
Tangara trains have a number of safety and vigilance devices installed, such as a deadman's brake, to address problems when the driver becomes incapacitated. If the driver releases pressure from this brake the train will come to a halt.
CityRail rolling stock are often divided into sets of four carriages: two driver and two driven (trailer) carriages. Four car services consist of one set of four, six car services consist of a set of four driven and two driver carriages and eight car services are two sets of four carriages.
The G-set in question, numbered G7, was a four car Tangara set that was fitted with an AC drive system for evaluation purposes. There was a driver in the forward driver carriage and a guard in the rear driver carriage. On this service, the guard, who could have applied the emergency brake, and the deadman's brake were the main safety mechanisms in place.
The train was later found to be travelling in excess of 117 km/h (73 mph) as it approached the 60 km/h (37 mph) curve where the accident occurred. Neither the deadman's brake nor the guard had intervened in this situation and this excessive speed was found to be the direct cause of the accident. Training of train staff was also found to be a contributing factor in the accident.
G7 was scrapped in 2005 due to the damage sustained in the accident; all four cars were damaged beyond repair.
These were the official findings of the NSW Ministry of Transport investigation to the accident. A report into the accident, headed by Commissioner Peter McInerney, was released in January 2004.[1]
[edit] Systemic causes
It was reported that the G7 set in question was said to have been reported for technical problems as many as twelve times and had developed a reputation, amongst the mechanical operations branch, saying that these problems were "normal" for the set in question. In the six months up to the accident three reports of technical problems were filed.
The inquiry found a number of flaws in the deadman's handle and facts related to the deadman's pedal:
- the dead weight of the unconscious and overweight driver appeared to be enough to defeat the deadman's pedal;
- the design of the deadman's pedal did not appear to be able to operate as intended with drivers of all shapes and sizes.
- marks near the deadman's pedal indicated that some drivers were wedging a conveniently sized signalling flag to defeat the deadman's pedal, in order to prevent their leg from cramping in the poorly configured foot well and to give themselves freedom of movement in the cabin.
Some of the technical problems included brake failure and power surge problems. After the accident these were often blamed by some for being the cause of the accident. Many of the survivors of the accident mentioned a large acceleration before the accident occurred. Furthermore, there was an understanding that the emergency brake should be seldom used because the train would accelerate between 5 and 10 km/h before the brake came into effect.
Official findings into the accident also blamed an "underdeveloped safety culture". There has been criticism of the way CityRail managed safety issues that arose, resulting in what the NSW Ministry of Transport called a "a reactive approach to risk management".
At the inquiry, Paul Webb, Queen's Counsel, representing the guard on the train, Bill Van Kessel, said that Van Kessel was in a microsleep at the time of the question, for up to 30 seconds, which would have removed the opportunity for the guard to put the train to a halt. Webb had also proposed that there had been attitudes that the driver was completely in charge of the train, that speeding was not an acceptable reason for the guard to slow or halt the train, which would have been a contributing factor in the accident.
Prior to this derailment, neither training nor procedures called for the guard to exercise control over the speed of the train by using the emergency brake pipe tap. Apart from the driver being considered to be the sole operator of the train, the emergency brake pipe tap does not offer the same degree of control over the automatic brake as a proper brake valve. The consensus among train crews was that a sudden emergency application from the rear could cause a breakaway and there was some evidence from previous accidents to support this view.
Since this derailment, CityRail training and operational procedures now emphasise the guard's responsibility to monitor the train's speed, and if need be open the emergency brake pipe tap to bring the train to a stop.
[edit] Changes implemented
All CityRail trains now have an additional safety feature, fitted since the accident. As well as the deadman handle and foot pedal, the driver is now required to acknowledge a vigilance button. If the train's driver does not use the controls and does not acknowledge the vigilance alarm, the vigilance system is activated and makes a penalty brake application. All trains have also been fitted with data loggers that record the driver's and guard's actions as they work the train, as well as the train's speed.[citation needed]
Rescue workers who attended the scene were impeded from accessing the trapped passengers on the train as they did not have the keys required to open the emergency exit doors. Emergency exit mechanisms have all been upgraded to allow them to be used without requiring a key. Railcorp is also planning to install internal emergency door release mechanisms to allow passengers to open the doors in an emergency.[citation needed]
Automatic Train Protection could have prevented this accident. Railcorp has tested ATP systems on the Blue Mountains line west of Penrith, and plans for ATP implementation across the CityRail network are being formulated.[citation needed]
[edit] External links
[edit] References
- ^ a b Special Commission of Inquiry into the Waterfall Rail Accident; Final Report Volume 1; January 2005; The Honourable Peter Aloysius McInerney QC
- ^ Australian Broadcasting Corporation, "Passengers still trapped in Sydney train wreckage" January 31 2008. Accessed 30 August 2008
- ^ Australian Broadcasting Corporation, "Seven killed in train accident" 31 January 2003. Accessed 30 August 2008
Retrieved from "http://en.wikipedia.org/wiki/Waterfall_rail_accident"
Sleep debt
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Sleep debt is the cumulative effect of not getting enough sleep. A large sleep debt may lead to mental and/or physical fatigue.
There are two kinds of sleep debt, caused by partial sleep deprivation or total sleep deprivation. Partial sleep deprivation occurs when a person or a lab animal sleeps too little for many days or weeks. Total sleep deprivation means being kept awake for many days or weeks.[1] There is debate in the scientific community over the specifics of sleep debt.
Contents[hide] |
Scientific debate
There is debate among researchers as to whether the concept of sleep debt describes a measurable phenomenon. The September 2004 issue of the journal Sleep contained dueling editorials from two of the world's leading sleep researchers: David F. Dinges and Jim Horne.
A 1997 experiment conducted by psychiatrists at the University of Pennsylvania School of Medicine[2] suggested that cumulative nocturnal sleep debt affects daytime sleepiness, particularly on the first, second, sixth, and seventh days of sleep restriction.
Evaluation
Sleep debt has been tested in a number of studies, most notably by Klerman and Dijk, through the use of a sleep onset latency test.[3] This test attempts to measure how easily a person can fall asleep. When this test is done several times during a day, it is called a multiple sleep latency test (MSLT). The subject is told to go to sleep and is awakened after a short period of time to determine the amount of time it took to fall asleep.
However, one does not have to go to a sleep clinic to try this experiment; a home process has been considered: it involves relaxing quietly and alone for a short amount of time. If the feeling of sleep comes fairly easily, one is considered to have sleep debt. Some also suggest that the quality of sleep can have an effect on the level of one's sleep debt.
The Epworth Sleepiness Scale (ESS) is among the tools used to screen for potential sleep debt. Specifically, the ESS, created by Australian researchers, is a simple eight item questionnaire with scores ranging 0-24.
A January 2007 study[4] suggests that saliva tests of the enzyme amylase could be used to indicate sleep debt, as the enzyme increases its activity in correlation with the length of time a subject has been deprived of sleep.
Across society
|
| The examples and perspective in this section may not represent a worldwide view of the subject. Please improve this article and discuss the issue on the talk page. |
The National Geographic Magazine reported the demands of work, social activities, and the availability of 24-hour home entertainment and internet access have caused people to sleep less now than in premodern times.[5] However, Jim Horne, a sleep researcher at Loughborough University, questions such claims. In a 2004 editorial in the journal Sleep, he notes available data suggest the average number of hours of sleep in a 24-hour period has not changed significantly in recent decades among adults.[citation needed]
Comparing data collected from the Bureau of Labor Statistics' American Time Use Survey[6] from 1965-1985[7] and 1998-2001,[8] shows that the median amount of sleep, napping, and resting done by the average adult American has changed by less than 0.7%, from a median of 482 minutes per day from 1965 through 1985, to 479 minutes per day from 1998 through 2001. Furthermore, the editorial suggests that there is a range of normal sleep time required by healthy adults, and many indicators used to suggest chronic sleepiness among the population as a whole do not stand up to scientific scrutiny.
See Also
Sleep deprivation
From Wikipedia, the free encyclopedia
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| This article needs additional citations for verification. |
Sleep deprivation, having too little sleep, can be either chronic or acute. Long-term sleep deprivation causes death in lab animals. A chronic sleep-restricted state can cause fatigue, daytime sleepiness, clumsiness and weight gain.
Complete absence of sleep over long periods is impossible to achieve; brief microsleeps cannot be avoided.[1]
Contents[hide] |
[edit] Physiological effects
Main health effects of sleep deprivation.[2] ADHD = Attention-deficit hyperactivity disorder
Generally, lack of sleep may result in[3][4]
- aching muscles[5]
- dizzyness and nausea
- headaches
- hallucinations[6]
- hand tremors[7]
- irritability[3]
- memory lapses or loss[8]
- yawning[3]
- temper tantrums in children[3]
- symptoms similar to:
[edit] Diabetes
A large (over 1400 participants) study in 2005 showed 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.[11] A 2000 study, by the UCSD School of Medicine and the Veterans Affairs Healthcare System in San Diego, used functional magnetic resonance imaging technology to monitor activity in the brains of sleep-deprived subjects performing simple verbal learning tasks.[12] The study showed that regions of the brain's prefrontal cortex displayed more activity in sleepier subjects. Depending on the task at hand, the brain would sometimes attempt 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.
A 2001 study at Chicago Medical Institute suggested that sleep deprivation may be linked to more serious diseases, such as heart disease and mental illnesses, such as psychosis and bipolar disorder.[13] The link between sleep deprivation and psychosis (psychiatric disorders) was further documented in 2007 through a study at Harvard Medical School and the University of California at Berkeley. The study revealed, using MRI scans, that lack of sleep causes the brain to become incapable of putting an emotional event into the proper perspective and incapable of making a controlled, suitable response to the event.
A 2002 University of California animal study indicated that REM sleep was necessary for turning off neurotransmitters and allowing their receptors to "rest" and regain sensitivity which allows monoamines (norepinephrine, serotonin and histamine) to be effective at naturally produced levels. This leads to improved regulation of mood and increased learning ability. The study also found that REM sleep deprivation can alleviate clinical depression because it mimics selective serotonin reuptake inhibitors (SSRI).
This is because the natural decrease in monoamines during REM is not allowed to occur, which causes the concentration of neurotransmitters in the brain, that are depleted in clinically depressed persons, to increase. Sleep outside of the REM phase may allow enzymes to repair brain cell damage caused by free radicals. High metabolic activity while awake damages the enzymes themselves preventing efficient repair. This study observed the first evidence of brain damage in rats as a direct result of sleep deprivation.[14]
Animal studies suggest that sleep deprivation increases stress hormones, which may reduce new cell production in adult brains.[15]
[edit] Effects on growth
A 1999 study[16] found that sleep deprivation resulted in reduced cortisol secretion the next day, driven by increased subsequent slow-wave sleep. Sleep deprivation was found to enhance activity on the Hypothalamic-pituitary-adrenal axis (which controls reactions to stress and regulates body functions such as digestion, the immune system, mood, sex, or energy usage) while suppressing growth hormones. The results supported previous studies, which observed adrenal insufficiency in idiopathic hypersomnia.
[edit] Effects on the healing process
A study conducted in 2005 showed that a group of rats which were deprived of REM sleep for five days had no significant effect on their ability to heal wounds, compared to a group of rats not deprived of "dream" sleep.[17] The rats were allowed deep (NREM) sleep. However, another study conducted by Gumustekin et al.[18] in 2004 showed sleep deprivation hindering the healing of burns on rats.
[edit] Impairment of ability
According to a 2000 study published in the British Medical Journal, researchers in Australia and New Zealand reported that sleep deprivation can have some of the same hazardous effects as being drunk.[19] 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 (Canada, the U.S. and U.K. set their blood alcohol limits at .08 percent).
In addition, as a result of 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 in the USA alone are caused by fatigue and drowsiness.[20] 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.[21]
The response latency seem to be higher when it comes to actions regarding personal morality rather than in situations when morality is not in question. The willingness to violate a personal belief has been shown to be moderated by EQ, so people with high EQ are affected less by sleep deprivation in such situations.[22]
[edit] Obesity
Several large studies using nationally representative samples suggest that the obesity problem the United States might have as one of its causes a corresponding decrease in the average number of hours that people are sleeping.[23][24][25] The findings suggest that this might be happening because sleep deprivation could be disrupting hormones that regulate glucose metabolism and appetite.[26]
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] Uses
[edit] Scientific study
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. Sleep deprivation can result in a form of psychosis if sleep is deprivated for more than 5 days.[citation needed]
Some sleep deprivation techniques are as follows:
- 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.[27] Although subjective,[28] this technique is used for total sleep deprivation as well as REM or NREM sleep deprivation.
This rat is being deprived of restful REM sleep by an animal researcher using a single platform ("flower pot") technique. The water is within 1 cm of the small flower pot bottom platform where the rat sits. At the onset of REM sleep, the exhausted rat would either fall into the deep water only to clamber back to its pot to avoid death from drowning, or its nose would become submerged into the water shocking it back to an awakened state.
- single platform: probably one of the first scientific methods (see Jouvet, 1964[29] for cats[30] and for rodents). During the sleep deprivation period, the animal is placed on an inverted flower pot whose bottom diameter is small 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 waken 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,[31] 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.[32]
[edit] Torture
Sleep deprivation can be used as a means of interrogation that some believe will constitute torture when used to excess. Under one interrogation technique, a subject might be kept awake for several days and when finally allowed to fall asleep, suddenly awakened and questioned. Menachem Begin, the Prime Minister of Israel from 1977-83, described his experience of sleep deprivation when a prisoner of the KGB in Russia as follows:
In the head of the interrogated prisoner, a haze begins to form. His spirit is wearied to death, his legs are unsteady, and he has one sole desire: to sleep...Anyone who has experienced this desire knows that not even hunger and thirst are comparable with it.[33]
Sleep deprivation is one of the five techniques used by the British government in the 1970s. The European Court of Human Rights ruled that the five techniques "did not occasion suffering of the particular intensity and cruelty implied by the word torture ... [but] amounted to a practice of inhuman and degrading treatment", in breach of the European Convention on Human Rights.[34]
In 2006, Australian Federal Attorney-General Philip Ruddock argued that sleep deprivation does not constitute torture.[35] In rats, prolonged, complete sleep deprivation increases both food intake and energy expenditure, leading to weight loss and, ultimately, death.[36] 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."[37]
[edit] 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. It has been shown that chronotype is related to the effect of sleep deprivation on mood in normal people; those with morningness circadian preference show an increase in depression-dejection scores while those with eveningness preference show a significant decrease.[38]
The incidence of relapse can be decreased by combining sleep deprivation with medication.[39] Many tricyclic antidepressants happen to suppress REM sleep, providing additional evidence for a link between mood and sleep.[40] Similarly, tranylcypromine has been shown to completely suppress REM sleep at adequate doses.
[edit] Voluntary
Sleep deprivation has sometimes been self-imposed to achieve personal notoriety in the context of record-breaking stunts. One such record belonged to Randy Gardner, who stayed awake for 264 hours (eleven days). Lt. Cmdr. John J. Ross of the US Navy Medical Neuropsychiatric Research Unit later published an account of this event, which became well known among sleep-deprivation researchers. In 2004, Shattered was a controversial British reality television competition where contestants competed to go for 7 full days sleeping just one hour per day.
[edit] Causes and treatments
[edit] School
A National Sleep Foundation survey found that college/university-aged students get an average of 6.8 hours of sleep each night.[41] Sleep deprivation is common in college freshmen as they adjust to the stress and social activities of college life. A study performed by the Department of Psychology at the National Chung Cheng University in Taiwan concluded that freshmen received the shortest amount of sleep during the week.[42]
Students get more sleep each night in the summer than during the school year,[citation needed] and one in four U.S. high school students admit to falling asleep in class at least once a week.[43] Research has indicated that teenage children have a variation in their circadian cycle that delays sleep past the normal time for adults. Since school schedules are based around the adult workday, it is not surprising that students have difficulty obtaining adequate sleep.[citation needed]
In 1997 the University of Minnesota did research that compared students who went to school at 7:15 a.m. and those who went to school at 8:40 a.m. They found that students who went to school at 8:40 got higher grades and more sleep on the weekdays.[20]
[edit] Longest period without sleep
Depending on how sleep is defined, there are several people who can claim the record for having gone the longest without sleep:
- Thai Ngoc, born 1942, claimed in 2006 to have been awake for 33 years or 11,700 nights, according to Vietnamese news organization Thanh Nien. It was said that Ngoc acquired the ability to go without sleep after a bout of fever in 1973,[44] but other reports indicate he stopped sleeping in 1976 with no known trigger.[45] At the time of the Thanh Nien report, Ngoc suffered from no apparent ill effect (other than a minor decline in liver function), was mentally sound and could carry 100 kg of pig feed down a 4 km road,[44] but another report indicates that he was healthy before the sleepless episode but that now he was not feeling well because of the lack of sleep.[45]
- In January 2005, the RIA Novosti published an article about Fyodor Nesterchuk from the Ukrainian town of Kamen-Kashirsky who claimed to have not slept in more than 20 years. Local doctor Fyodor Koshel, chief of the Lutsk city health department, claimed to have examined him extensively and failed to make him sleep. Koshel also said however that Nesterchuck did not suffer any of the normally deleterious effects of sleep deprivation.[46] People who claim not to sleep are usually shown to sleep when studied in sleep laboratories with EEG. Nesterchuck reports experiencing drowsiness at night, commenting that he attempts to sleep "in vain" when he notices his eyelids drooping. Many people experience microsleep episodes during sleep deprivation, in which they sleep for periods of seconds to fractions of a second and frequently don't remember these episodes. Because microsleep is frequently not remembered, microsleep or a related phenomenon may be responsible for lack of sleep and/or lack of memory of sleep in individuals like Nesterchuk and Thai Ngoc.
- Randy Gardner holds the scientifically documented record for the longest period of time a human being has intentionally gone without sleep not using stimulants of any kind. Gardner stayed awake for 264 hours (eleven days), breaking the previous record of 260 hours held by Tom Rounds of Honolulu.[47] Other sources claim Gardner's record was broken two weeks later by another student, Jim Thomas of Fresno State College, who stayed awake for 266.5 hours; and state that the Guinness World Records record is 449 hours (18 days, 17 hours) by Maureen Weston, of Peterborough, Cambridgeshire in April, 1977, in a rocking-chair marathon.[48]
- A 3-year-old boy named Rhett Lamb[49] of St. Petersburg Florida has a rare condition and has only slept for one to two hours per day in the past three years. He has a rare abnormality called an Arnold-Chiari malformation where brain tissue protrudes into the spinal canal. The skull puts pressure on the protruding part of the brain. It is not yet known if the brain malformation is directly related to his sleep deprivation.
[edit] See also
- Fatigue
- Insomnia
- Microsleep
- Narcolepsy
- Polyphasic sleep
- Randy Gardner - sleep deprivation record holder
- Sleep debt
- Sleep medicine
- Sleep onset latency
- Touch the Truck
- Fatal Familial Insomnia
- Wake therapy
Example
Teen driver's micro sleep proves fatal for cyclist
Georgina Robinson
May 11, 2009
A woman flung from her bicycle after a young driver fell asleep at the wheel of a truck on the NSW North Coast yesterday "didn't have a chance", police say.
The 41-year-old woman was cycling south along a narrow road shoulder on a bridged section of the Pacific Highway just north of Byron Bay yesterday morning when the hire truck hit her from behind.
She was thrown off the bike and over the side of the bridge into thick scrub near an old railway line, dying instantly.
Police today said the 18-year-old truck driver told investigators he fell asleep for a moment, causing the truck to veer left.
"He appears to have started nodding off with fatigue and veered to the left hand side of the road into the guard rail and she was in front so he's hit her from behind," Senior Constable Mitch McMullen, from the Ballina crash investigation unit, said.
"She got ejected off the bike and over the railing."
Police have interviewed the driver and his 22-year-old passenger, who was asleep when the crash occurred.
The men told investigators they had hired the Pantech truck to make a pick up on the Gold Coast and were on their way back to Sydney about 7am, Senior Constable McMullen said.
They had been on the road for about an hour and a half and had not driven through the night.
Senior Constable McMullen said the woman, from the small town of Tyagarah about eight kilometres north of Byron Bay, was cycling on a narrow section of road shoulder - about half a metre wide - and would have died instantly from the truck's impact.
"All the evidence points to the fact that she was to the far left as possible and the truck is actually scraping along the safety rail prior to the impact, then the impact (occurred)," he said.
"She didn't have a chance."
The men stopped twice following the smash, once in a road bay about 100m south of the accident and then again, about five kilometres away, after turning off the highway onto Ewingsdale Road to wait for police, who found them "in a state of shock".
The truck's front end was badly damaged, police said.
No charges have been laid. Senior Constable McMullen said police were waiting on the results of routine blood tests.
It was not known if the woman had children or was married. Her parents had been informed, he said.
Detail Definition
A phenomenon usually associated with the effects of sleep deprivation. They are very short periods of sleep (measured in seconds), of which the person experiencing them may not even be aware.
If you have seen someone doing the uncontrollable head nod in a lecture, you're watching someone who is rapidly going beyond the mere microsleep, and is now fully intent on sleeping while sitting. If you are experiencing that 'I can't keep my eyes open' feeling, and you failed to do so, congratulations: you just had a microsleep.
It's my presumption that many single vehicle accidents result from microsleeps. You don't really need to fall fully asleep to find a tree; a couple of seconds can do it. Do not drive while sleep deprived on a regular basis, as it is comparable to driving under the influence of drugs. In fact, it is really the same thing, they're just your own personal internally released sedatives (as well as brain activity supression, but that's for the neuropsychologists).
Microsleeps are often the cause of short term memory deficits, increased reaction times, and generally poorer task performance associated with sleep deprivation, since presented stimuli may not actually be registered by the subject during a microsleep. The same mechanism can also explain some longer term effects on memory (but it is not the only agent).
