General Reading 10 - Passage 3
LACK OF SLEEP
	Section A
	It is estimated that the average man or woman needs between seven-and-a-half 
	and eight hours' sleep a night. Some can manage on a lot less. Baroness Thatcher, 
	for example, was reported to be able to get by on four hours' sleep a night 
	when she was Prime Minister of Britain. Dr Jill Wilkinson, senior lecturer in 
	psychology at Surrey University and co-author of 'Psychology in Counselling 
	and Therapeutic Practice', states that healthy individuals sleeping less than 
	five hours or even as little as two hours in every 24 hours are rare, but represent 
	a sizeable minority.
	Section B
	The latest beliefs are that the main purposes of sleep are to enable the body 
	to rest and replenish, allowing time for repairs to take place and for tissue 
	to be regenerated. One supporting piece of evidence for this rest-and-repair 
	theory is that production of the growth hormone somatotropin, which helps tissue 
	to regenerate, peaks while we are asleep. Lack of sleep, however, can compromise 
	the immune system, muddle thinking, cause depression, promote anxiety and encourage 
	irritability.
	Section C
	Researchers in San Diego deprived a group of men of sleep between Sam and lam 
	on just one night, and found that levels of their bodies' natural defences against 
	viral infections had fallen significantly when measured the following morning. 
	'Sleep is essential for our physical and emotional well-being and there are 
	few aspects of daily living that are not disrupted by the lack of it', says 
	Professor William Regelson of Virginia University, a specialist in insomnia. 
	'Because it can seriously undermine the functioning of the immune system, sufferers 
	are vulnerable to infection.'
	Section D
	For many people, lack of sleep is rarely a matter of choice. Some have problems 
	getting to sleep, others with staying asleep until the morning. Despite popular 
	belief that sleep is one long event, research shows that, in an average night, 
	there are five stages of sleep and four cycles, during which the sequence of 
	stages is repeated.
	
	In the first light phase, the heart rate and blood pressure go down and the 
	muscles relax. In the next two stages, sleep gets progressively deeper. In stage 
	four, usually reached after an hour, the slumber is so deep that, if awoken, 
	the sleeper would be confused and disorientated. It is in this phase that sleep-walking 
	can occur, with an average episode lasting no more than 15 minutes.
In the fifth stage, the rapid eye movement (REM) stage, the heartbeat quickly gets back to normal levels, brain activity accelerates to daytime heights and above and the eyes move constantly beneath closed lids as if the sleeper is looking at something. During this stage, the body is almost paralysed. This REM phase is also the time when we dream.
	Section E
	Sleeping patterns change with age, which is why many people over 60 develop 
	insomnia. In America, that age group consumes almost half the sleep medication 
	on the market. One theory for the age-related change is that it is due to hormonal 
	changes. The temperature rise occurs at 
	daybreak in the young, but at three or four in the morning in the elderly. Age 
	aside, it is estimated that roughly one in three people suffer some kind of 
	sleep disturbance. Causes can be anything from pregnancy and stress to alcohol 
	and heart disease. Smoking is a known handicap to sleep, with one survey showing 
	that ex-smokers got to sleep in 18 minutes rather than their earlier average 
	of 52 minutes.
	Section F
	Apart from self-help therapy such as regular exercise, there are psychological 
	treatments, including relaxation training and therapy aimed at getting rid of 
	pre-sleep worries and anxieties. There is also sleep reduction therapy, where 
	the aim is to improve sleep quality by strictly regulating the time people go 
	to bed and when they get up. Medication is regarded by many as a last resort 
	and often takes the form of sleeping pills, normally benzodiazepines, which 
	are minor tranquillisers.
	Section G
	Professor Regelson advocates the use of melatonin for treating sleep disorders. 
	Melatonin is a naturally secreted hormone, located in the pineal gland deep 
	inside the brain. The main function of the hormone is to control the body's 
	biological clock, so we know when to sleep and when to wake. The gland detects 
	light reaching it through the eye; when there is no light, it secretes the melatonin 
	into the bloodstream, lowering the body temperature and helping to induce sleep. 
	Melatonin pills contain a synthetic version of the hormone and are commonly 
	used for jet lag as well as for sleep disturbance. John Nicholls, sales manager 
	of one of America's largest health food shops, claims that sales of the pill 
	have increased dramatically. He explains that it is sold in capsules, tablets, 
	lozenges and mixed with herbs. It is not effective for all insomniacs, but many 
	users have weaned themselves off sleeping tablets as a result of its application.