Mining and Refining
(1) In an industrial society like the United States, the most important nonfuel resources are iron ore, aluminum ore, copper ore, and minerals containing nitrogen, phosphorus, and potassium used in fertilizers, a lot of energy is used in mining operations and the transportation of ore. To make the task of any physical extraction and transportation worthwhile, the ores must contain enough of the required compound or clement. Some low-grade ore is not usable because of the cost of the mining process.
(2) Materials extracted from the earth are processed by screening, separating, washing and grinding. Often, the useful element in an ore is in a chemical form that is not usable and must be changed to a desirable form. For instance, the aluminum in aluminum ore is in the form of aluminum ion. To be useful, the aluminum ion needs to be changed to aluminum metal.

The word extracted in Paragraph (2) is closest in meaning to …………………

Mining and Refining
(1) In an industrial society like the United States, the most important nonfuel resources are iron ore, aluminum ore, copper ore, and minerals containing nitrogen, phosphorus, and potassium used in fertilizers, a lot of energy is used in mining operations and the transportation of ore. To make the task of any physical extraction and transportation worthwhile, the ores must contain enough of the required compound or clement. Some low-grade ore is not usable because of the cost of the mining process.
(2) Materials extracted from the earth are processed by screening, separating, washing and grinding. Often, the useful element in an ore is in a chemical form that is not usable and must be changed to a desirable form. For instance, the aluminum in aluminum ore is in the form of aluminum ion. To be useful, the aluminum ion needs to be changed to aluminum metal.

The word worthwhile in paragraph (1) is closest in meaning to …………

Greenhouse effect
(1) The greenhouse effect is a naturally occurring process that aids in heating the Earth's surface and atmosphere. It results from the fact that certain atmospheric gases, such as carbon dioxide, water vapor, and methane, are able to change the energy balance of the planet by absorbing long wave radiation emitted from the Earth's surface. Without the greenhouse effect life on this planet would probably not exists, as the average temperature of the Earth would be a chilly-18 º Celsius, rather than the present 15 º.
(2) As energy from the Sun passes through the atmosphere a number of things take place. A portion of the energy (26% globally) is reflected or scattered back to space by clouds and other atmospheric particles. About 19% of the energy available is absorbed by clouds, gases (like ozone), and particles in the atmosphere. Of the remaining 55% of the solar energy passing through the Earth’s atmosphere. 4% is reflected from the surface back to space. On average, about 51% of the Sun's radiation reaches the surface. This energy is then used in a number of processes, including the heating of the ground surface; the melting of ice and snow and the evaporation of water; and plant photosynthesis.
(3) The heating of the ground by sunlight causes the Earth's surface to become a radiator of energy in the long wave band (sometimes called in the radiation). This emission of energy is generally directed to space. However, only a small portion of this energy actually makes it back to space. The majorly of the outgoing infrared radiation is absorbed by the greenhouse gases.
(4) Absorption of long wave radiation by the atmosphere Causes additional heat energy to be added to the Earth's atmospheric system. The now warner atmospheric greenhouse gas molecules begin radiating long wave energy in all directions. Over 90% of this emission of long wave energy is directed back to the Earth's surface where it once again is absorbed by the surface. The heating of the ground by the long wave radiation causes the ground surface to once again radiate, repeating the cycle described above, again and again, until no more long wave is available for absorption.
(5) The amount of heat energy added to the atmosphere by the greenhouse effect is controlled by the concentration of greenhouse in the Earth's atmosphere. All of the major greenhouse gases have increased in concentration since the beginning of the industrial Revolution. As a result of these higher concentrations. Scientists predict that the greenhouse effect will be enhanced and the Earth's climate will become warmer. Predicting the amount of warming is accomplished by computer modeling Computer models suggest that a doubling of the concentration of the main greenhouse as carbon dioxide, may raise the average global temperature between 1 and 3º Celsius. However, the numeric equations of computer models do not accurately simulate the effects of a number of possible negative feedbacks. For example, many of the models cannot property Simulate late the negative effects that increased cloudier. These extra clouds would then reflect a greater proportion of the sun’s energy back to space reducing the amount of molar radiation absorbed by the atmosphere and the Earth’s surface. With less solar energy being absorbed at the surface, the effects of an enhanced greenhouse effect may be counteracted.
(6) A number of gases are involved in the human caused enhancement of the greenhouse effect. These gases include carbon dioxide (CO2): methane (CH4): nitrous oxide: (N2O): chlorofluorocarbons (CFC): and troposphere ozone (O3). Of these gases the single most important gas in carbon dioxide, which accounts for about 55% of the change in the intensity of the Earth’s greenhouse effect. The contributions of the other gases are 25% for chlorofluorocarbons, 15% for methane, and 5% for nitrous oxide. Ozone’s contribution to the enhancement of greenhouse effect is still yet to be quantified.
(7) Average concentrations of atmospheric carbon dioxide in the year 2005 were about 380 parts per million. Prior to 1700, levels of carbon dioxide were about 280 parts per million. This increase in carbon dioxide in the atmosphere is primarily due to the activities of humans. Beginning in 1700, societal change brought about by the industrial Revolution. Increased the amount of carbon dioxide entering the atmosphere. The major Sources of this gas include fossil fuel combustion for industry, Transportation, space heating, electricity generation, and cooking, and vegetation changes in natural prairie, woodland, and forested ecosystems. Emissions from fossil fuel combustion account for about 65% of the extra carbon dioxide now found in our atmosphere. The remaining 35% is derived from deforestation and the conversion of prairie, woodland and forested ecosystems primarily into agricultural systems.
(8) Artificially created chlorofluorocarbons (CFCs) are the strongest greenhouse gas per molecule. However, low concentrations in the atmosphere reduce their overall importance in the enhancement of the greenhouse effect. Current measurements in the atmosphere indicate that the concentration of these chemicals may soon begin declining because of reduced emissions. Reports of the development of ozone holes over the North and Saud Boles and a general decline in global Stratosphere ozone level over the last two decades has caused many nations to cut back on their production and use of the chemicals. In 1987, the signing of the Montreal Protocol agreement by forty-six nations established an immediate timetable for the global reduction of CFC production and use.
(9) Since 1750, methane concentrations in the atmosphere have increased by more than 150%. The primary sources for the additional methane added to the atmosphere (in order of importance) are rice cultivation, domestic grazing animals, termites, landfills, coal mining, and oil, and gas extraction. Anaerobic
conditions associated with rice paddy flooding results in the formation of methane gas. However, an accurate estimate of how much methane is being produced from rice paddies has been difficult to obtain. More than 60% of all rice paddies are found in India and China were scientific data concerning emission rates are unavailable. Nevertheless, scientists believe that the contribution of rice paddies is large because this form of crop production has more than doubled since 1950.

Which three man-made gases have had the greatest greenhouse effect?

Greenhouse effect
(1) The greenhouse effect is a naturally occurring process that aids in heating the Earth's surface and atmosphere. It results from the fact that certain atmospheric gases, such as carbon dioxide, water vapor, and methane, are able to change the energy balance of the planet by absorbing long wave radiation emitted from the Earth's surface. Without the greenhouse effect life on this planet would probably not exists, as the average temperature of the Earth would be a chilly-18 º Celsius, rather than the present 15 º.
(2) As energy from the Sun passes through the atmosphere a number of things take place. A portion of the energy (26% globally) is reflected or scattered back to space by clouds and other atmospheric particles. About 19% of the energy available is absorbed by clouds, gases (like ozone), and particles in the atmosphere. Of the remaining 55% of the solar energy passing through the Earth’s atmosphere. 4% is reflected from the surface back to space. On average, about 51% of the Sun's radiation reaches the surface. This energy is then used in a number of processes, including the heating of the ground surface; the melting of ice and snow and the evaporation of water; and plant photosynthesis.
(3) The heating of the ground by sunlight causes the Earth's surface to become a radiator of energy in the long wave band (sometimes called in the radiation). This emission of energy is generally directed to space. However, only a small portion of this energy actually makes it back to space. The majorly of the outgoing infrared radiation is absorbed by the greenhouse gases.
(4) Absorption of long wave radiation by the atmosphere Causes additional heat energy to be added to the Earth's atmospheric system. The now warner atmospheric greenhouse gas molecules begin radiating long wave energy in all directions. Over 90% of this emission of long wave energy is directed back to the Earth's surface where it once again is absorbed by the surface. The heating of the ground by the long wave radiation causes the ground surface to once again radiate, repeating the cycle described above, again and again, until no more long wave is available for absorption.
(5) The amount of heat energy added to the atmosphere by the greenhouse effect is controlled by the concentration of greenhouse in the Earth's atmosphere. All of the major greenhouse gases have increased in concentration since the beginning of the industrial Revolution. As a result of these higher concentrations. Scientists predict that the greenhouse effect will be enhanced and the Earth's climate will become warmer. Predicting the amount of warming is accomplished by computer modeling Computer models suggest that a doubling of the concentration of the main greenhouse as carbon dioxide, may raise the average global temperature between 1 and 3º Celsius. However, the numeric equations of computer models do not accurately simulate the effects of a number of possible negative feedbacks. For example, many of the models cannot property Simulate late the negative effects that increased cloudier. These extra clouds would then reflect a greater proportion of the sun’s energy back to space reducing the amount of molar radiation absorbed by the atmosphere and the Earth’s surface. With less solar energy being absorbed at the surface, the effects of an enhanced greenhouse effect may be counteracted.
(6) A number of gases are involved in the human caused enhancement of the greenhouse effect. These gases include carbon dioxide (CO2): methane (CH4): nitrous oxide: (N2O): chlorofluorocarbons (CFC): and troposphere ozone (O3). Of these gases the single most important gas in carbon dioxide, which accounts for about 55% of the change in the intensity of the Earth’s greenhouse effect. The contributions of the other gases are 25% for chlorofluorocarbons, 15% for methane, and 5% for nitrous oxide. Ozone’s contribution to the enhancement of greenhouse effect is still yet to be quantified.
(7) Average concentrations of atmospheric carbon dioxide in the year 2005 were about 380 parts per million. Prior to 1700, levels of carbon dioxide were about 280 parts per million. This increase in carbon dioxide in the atmosphere is primarily due to the activities of humans. Beginning in 1700, societal change brought about by the industrial Revolution. Increased the amount of carbon dioxide entering the atmosphere. The major Sources of this gas include fossil fuel combustion for industry, Transportation, space heating, electricity generation, and cooking, and vegetation changes in natural prairie, woodland, and forested ecosystems. Emissions from fossil fuel combustion account for about 65% of the extra carbon dioxide now found in our atmosphere. The remaining 35% is derived from deforestation and the conversion of prairie, woodland and forested ecosystems primarily into agricultural systems.
(8) Artificially created chlorofluorocarbons (CFCs) are the strongest greenhouse gas per molecule. However, low concentrations in the atmosphere reduce their overall importance in the enhancement of the greenhouse effect. Current measurements in the atmosphere indicate that the concentration of these chemicals may soon begin declining because of reduced emissions. Reports of the development of ozone holes over the North and Saud Boles and a general decline in global Stratosphere ozone level over the last two decades has caused many nations to cut back on their production and use of the chemicals. In 1987, the signing of the Montreal Protocol agreement by forty-six nations established an immediate timetable for the global reduction of CFC production and use.
(9) Since 1750, methane concentrations in the atmosphere have increased by more than 150%. The primary sources for the additional methane added to the atmosphere (in order of importance) are rice cultivation, domestic grazing animals, termites, landfills, coal mining, and oil, and gas extraction. Anaerobic
conditions associated with rice paddy flooding results in the formation of methane gas. However, an accurate estimate of how much methane is being produced from rice paddies has been difficult to obtain. More than 60% of all rice paddies are found in India and China were scientific data concerning emission rates are unavailable. Nevertheless, scientists believe that the contribution of rice paddies is large because this form of crop production has more than doubled since 1950.

How much energy is reflected into space by the earth's atmosphere and the earth's surface?

(1) Since 1876, when Henry Heinz first started selling ketchup in glass bottles, people have been arguing over the best way to get the condiment out of the packaging and onto their plates. A physicist decided to apply a little science to the matter and now has found what he calls a scientifically optimized method for getting the ketchup to flow.
(2) While it may look like a liquid, ketchup is actually a non-Newtonian fluid. Instead of flowing consistently the viscosity of these substances change with the amount of force put on them.
(3) Because of the physics that govern ketchup's viscosity, packaging them in glass bottles makes it much harder to hit that pressure sweet spot. But if you' re dedicated on sticking to the classics and not switching to squeeze bottles, Stickland has developed a method based on physics for coaxing ketchup out of the bottle, Daisy Meager reports for Munchies.
(4) You have to start by giving the sauce a good shake," Stickland says in a statement.
(5) The next step is to flip the bottle upside-down (with the lid still on). Then, shake the bottle until the ketchup has slid into its neck. Lastly, turn the bottle so that it's pointing towards your meal at a 45-degree angle and uncap. If needed, Stickland says to give the ketchup a little "encouragement" by tapping on the bottom of the bottle-gently at first, but with increasing force until it finally slides out and onto the plate. "The trick is to get the sauce flowing, but not too fast."

Which word can we use to replace the word While in Paragraph (2)?

(1) Since 1876, when Henry Heinz first started selling ketchup in glass bottles, people have been arguing over the best way to get the condiment out of the packaging and onto their plates. A physicist decided to apply a little science to the matter and now has found what he calls a scientifically optimized method for getting the ketchup to flow.
(2) While it may look like a liquid, ketchup is actually a non-Newtonian fluid. Instead of flowing consistently the viscosity of these substances change with the amount of force put on them.

What is the most important step in getting ketchup to flow?
(3) Because of the physics that govern ketchup's viscosity, packaging them in glass bottles makes it much harder to hit that pressure sweet spot. But if you' re dedicated on sticking to the classics and not switching to squeeze bottles, Stickland has developed a method based on physics for coaxing ketchup out of the bottle, Daisy Meager reports for Munchies.
(4) You have to start by giving the sauce a good shake," Stickland says in a statement.
(5) The next step is to flip the bottle upside-down (with the lid still on). Then, shake the bottle until the ketchup has slid into its neck. Lastly, turn the bottle so that it's pointing towards your meal at a 45-degree angle and uncap. If needed, Stickland says to give the ketchup a little "encouragement" by tapping on the bottom of the bottle-gently at first, but with increasing force until it finally slides out and onto the plate. "The trick is to get the sauce flowing, but not too fast."

Stages or Economic Activity
(1) There are three main stages of economic activity, these stages are typical of nearly all production and they are called the levels of economic — or business - activity:
(2) Stage 1 is called the primary stage of production. This stage involves the earth's natural resources. Activities in the primary sector of industry include farming, fishing, forestry and the extraction of natural materials, such as oil and copper ore.
(3) Stage 2 is called the secondary stage of production. This stage involves taking the materials and resources provided by the primary sector and converting them into manufactured or processed goods. Activities in the secondary sector of industry include building and construction, car manufacturing and computer assembly.
(4) Stage 3 is called the tertiary stage of production. This stage involves providing services to both consumers and other businesses. Activities in the tertiary sector of industry include transport, banking, retail, insurance, hotels and hairdressing.
(5) In some countries, primary industries such as mining employ many more people than manufacturing or service industries. These tend to be countries — often called developing countries — where manufacturing industry has only recently been established. As most people still live in the rural areas with low incomes, there is little demand for services such as transport, hotels and insurance. The levels of both employment and output in the primary sector in these countries are likely to be high. In countries which started up manufacturing industries many years ago, the secondary and tertiary sectors are likely to employ many more workers than the primary sector. The level of output in the primary sector is often small compared to the other two sectors.

What is one important idea in Paragraph (3) related to the secondary stage of production?

Stages or Economic Activity
(1) There are three main stages of economic activity, these stages are typical of nearly all production and they are called the levels of economic — or business - activity:
(2) Stage 1 is called the primary stage of production. This stage involves the earth's natural resources. Activities in the primary sector of industry include farming, fishing, forestry and the extraction of natural materials, such as oil and copper ore.
(3) Stage 2 is called the secondary stage of production. This stage involves taking the materials and resources provided by the primary sector and converting them into manufactured or processed goods. Activities in the secondary sector of industry include building and construction, car manufacturing and computer assembly.
(4) Stage 3 is called the tertiary stage of production. This stage involves providing services to both consumers and other businesses. Activities in the tertiary sector of industry include transport, banking, retail, insurance, hotels and hairdressing.
(5) In some countries, primary industries such as mining employ many more people than manufacturing or service industries. These tend to be countries — often called developing countries — where manufacturing industry has only recently been established. As most people still live in the rural areas with low incomes, there is little demand for services such as transport, hotels and insurance. The levels of both employment and output in the primary sector in these countries are likely to be high. In countries which started up manufacturing industries many years ago, the secondary and tertiary sectors are likely to employ many more workers than the primary sector. The level of output in the primary sector is often small compared to the other two sectors.

Which stage of production are hotels an example of?

Stages or Economic Activity
(1) There are three main stages of economic activity, these stages are typical of nearly all production and they are called the levels of economic — or business - activity:
(2) Stage 1 is called the primary stage of production. This stage involves the earth's natural resources. Activities in the primary sector of industry include farming, fishing, forestry and the extraction of natural materials, such as oil and copper ore.
(3) Stage 2 is called the secondary stage of production. This stage involves taking the materials and resources provided by the primary sector and converting them into manufactured or processed goods. Activities in the secondary sector of industry include building and construction, car manufacturing and computer assembly.
(4) Stage 3 is called the tertiary stage of production. This stage involves providing services to both consumers and other businesses. Activities in the tertiary sector of industry include transport, banking, retail, insurance, hotels and hairdressing.
(5) In some countries, primary industries such as mining employ many more people than manufacturing or service industries. These tend to be countries — often called developing countries — where manufacturing industry has only recently been established. As most people still live in the rural areas with low incomes, there is little demand for services such as transport, hotels and insurance. The levels of both employment and output in the primary sector in these countries are likely to be high. In countries which started up manufacturing industries many years ago, the secondary and tertiary sectors are likely to employ many more workers than the primary sector. The level of output in the primary sector is often small compared to the other two sectors.

What is the main topic of the passage?

Cost Benefit Analysis
(1) Cost-benefit analysis weighs the gains and losses to different individuals and suggests carrying out changes that provide greater benefits than harm. For example, a property tax used to build a local park creates a benefit to those who use the park, but harms those who own property (although, by increasing property values, even non-users obtain some benefits). Since some of the taxpayers won't use the park, it won't be the case that everyone benefits on balance. Cost-benefit analysis weighs the costs against the benefits. In the case of the park, the costs are readily monetized (turned into dollars), because the costs to the tax-payers are just the amount of the tax.
(2) In contrast, the benefits are much more challenging to estimate. Conceptually, the benefits are the amount the park users would be willing to pay to use the park if the park charged admission. However, if the park doesn't charge admission, we would have to estimate willingness-to-pay. In principle, the park provides greater benefits than costs if the benefits to the users exceed the losses to the taxpayers.
(3) The first step in the process is to compile a comprehensive list of all the costs and benefits associated with the project or decision. Costs should include direct and indirect costs, intangible costs, opportunity costs and the cost of potential risks. Benefits should include all direct and indirect revenues and intangible benefits, such as increased production from improved employee safety and morale, or increased sales from customer goodwill.

Which sentence gives the main idea of Paragraph (1)?

Cost Benefit Analysis
(1) Cost-benefit analysis weighs the gains and losses to different individuals and suggests carrying out changes that provide greater benefits than harm. For example, a property tax used to build a local park creates a benefit to those who use the park, but harms those who own property (although, by increasing property values, even non-users obtain some benefits). Since some of the taxpayers won't use the park, it won't be the case that everyone benefits on balance. Cost-benefit analysis weighs the costs against the benefits. In the case of the park, the costs are readily monetized (turned into dollars), because the costs to the tax-payers are just the amount of the tax.
(2) In contrast, the benefits are much more challenging to estimate. Conceptually, the benefits are the amount the park users would be willing to pay to use the park if the park charged admission. However, if the park doesn't charge admission, we would have to estimate willingness-to-pay. In principle, the park provides greater benefits than costs if the benefits to the users exceed the losses to the taxpayers.
(3) The first step in the process is to compile a comprehensive list of all the costs and benefits associated with the project or decision. Costs should include direct and indirect costs, intangible costs, opportunity costs and the cost of potential risks. Benefits should include all direct and indirect revenues and intangible benefits, such as increased production from improved employee safety and morale, or increased sales from customer goodwill.

What is the main idea in the passage?

Oceans
(1) The oceans make up 70 percent of the planet and contain 97 percent of all the water on Earth. It also makes up the vast majority of water stores, the majority of the planet's moisture, terrestrial energy, and heat from the sun. This energy is transferred between the equator and the two poles by larger surface currents, by winds and deep ocean currents driven by differences in ocean density. It also provides the moisture and energy for storm systems and ultimately global climates.
(2) As terrestrial creatures, humans think of the importance of the planet's land surfaces, yet Earth is a planet consisting of 70 percent water. From space, the dominance of water is obvious because most of it is stored in Earth's oceans.
(3) Earth would not be the same planet without its oceans. The oceans, along with the atmosphere, keep Earth's surface temperatures fairly constant worldwide. Some places on Earth reach as cold as -20 degrees Celsius, whereas other places reach as hot as 55 degrees Celsius. Yet on other planets like Mercury, temperatures range from -180 degrees Celsius to 430 degrees Celsius.

What is one important idea that the writer mentions?

Oceans
(1) The oceans make up 70 percent of the planet and contain 97 percent of all the water on Earth. It also makes up the vast majority of water stores, the majority of the planet's moisture, terrestrial energy, and heat from the sun. This energy is transferred between the equator and the two poles by larger surface currents, by winds and deep ocean currents driven by differences in ocean density. It also provides the moisture and energy for storm systems and ultimately global climates.
(2) As terrestrial creatures, humans think of the importance of the planet's land surfaces, yet Earth is a planet consisting of 70 percent water. From space, the dominance of water is obvious because most of it is stored in Earth's oceans.
(3) Earth would not be the same planet without its oceans. The oceans, along with the atmosphere, keep Earth's surface temperatures fairly constant worldwide. Some places on Earth reach as cold as -20 degrees Celsius, whereas other places reach as hot as 55 degrees Celsius. Yet on other planets like Mercury, temperatures range from -180 degrees Celsius to 430 degrees Celsius.

What is the writer's main purpose?

Sleep Disorders اضطرابات النو م
(1) The idea that "everyone needs 8 hours of sleep" is untrue. Newborns spend nearly two-thirds of their day asleep, most adults no more than one-third. Age. related differences in average time spent sleeping are rivaled by differences in the normal amount of sleep among individuals at any age. Some people thrive with fewer than 6 hours of sleep per night; others regularly sleep 9 hours or more. Sleep patterns may be genetically influenced. When two researchers, Wilse Webb and Scott Campbell, checked the pattern and duration of sleep among fraternal and identical twins, only the identical twins were strikingly similar.
(2) Whatever their normal need for sleep, some 10 to 15 percent of adults complain of insomnia - persistent problems in falling or staying asleep. True insomnia is not the occasional inability to sleep that we experience when anxious or excited. For a stressed organism, alertness is natural and adaptive. Moreover, from middle age on, sleep is seldom uninterrupted. Occasional awakenings become the norm, not something to fret over or treat with medication.
(3) Sometimes people fret unnecessarily about their sleep. Scientists have learned to doubt people's fretful sleep reports. In laboratory studies, insomnia complainers do get less sleep than others, but they typically overestimate, by about double, how long it took them to fall asleep, and they underestimate by nearly half how long they actually slept. Even if we've been awake only an hour or two, we may think we've had little sleep. because it's the waking part we remember. When researchers awaken people repeatedly during the night, some recall having slept soundly.
(4) The most common quick fixes for true insomnia - sleeping pills - can aggravate the problem. Both reduce REM sleep and can leave a person with next-day blahs. With continued use, one needs bigger doses to get an effect, and when the drug is discontinued, the insomnia may worsen. Scientists are searching for natural chemicals that are abundant during sleep and might be as a sleep aid without side effects. In the meantime, sleep experts offer other natural alternatives:
• Relax before bedtime, using dimmer light.
• Avoid caffeine (this includes chocolate) after late afternoon and avoid rich foods before bedtime. A glass of milk may help. (Milk provides raw materials for the manufacture of serotonin, a neurotransmitter that facilitates sleep.)
• Sleep on a regular schedule (rise at the same time even after a restless night) and avoid naps. A regular sleep schedule boosts daytime alertness, too, as shown in a recent experiment in which University of Arizona students slept 7.5 hours a night on either a varying or consistent schedule
• Exercise regularly but not in the late evening. (Late afternoon is best.)
• Reassure yourself that the temporary loss of sleep causes no great harm, certainly nothing worth losing sleep over.
• If nothing else works, aim for less sleep; go to bed later or get up earlier.
(5) More rare but also more severe than insomnia are the sleep disorders narcolepsy and sleep apnea. People with narcolepsy (from narco, "numbness, "and lepsy," seizure") suffer periodic, overwhelming sleepiness. This usually lasts less than 5 minutes but sometimes occurs at the most inopportune times, perhaps just after taking a terrific swing at a softball or when laughing loudly or shouting angrily. In severe cases, the person may collapse directly into a brief period of REM sleep, with its accompanying loss of muscular tension. Those who suffer from narcolepsy - 1 in 2000 people, estimates the Stanford University Center for Narcolepsy - must live with extra caution.
(6) The National Heart, Lung, and Blood Institute reports that 1 in 25 people (mostly overweight men) suffer from sleep apnea - a treatable disorder that was unknown before modern sleep research. They intermittently stop breathing during sleep. (Apnea means "stopping respiration”) After an airless minute or so, decreased blood oxygen arouses the sleeper to awaken and snort in air for a few seconds. The process can repeat more than 400 times a night, depriving the person of slow-wave sleep. Apart from complaints of sleepiness and irritability during the day - and their friends' complaints about their loud "snoring"- apnea sufferers are often unaware of their disorder.

Who did a study on sleep apnea?

Sleep Disorders اضطرابات النو م
(1) The idea that "everyone needs 8 hours of sleep" is untrue. Newborns spend nearly two-thirds of their day asleep, most adults no more than one-third. Age. related differences in average time spent sleeping are rivaled by differences in the normal amount of sleep among individuals at any age. Some people thrive with fewer than 6 hours of sleep per night; others regularly sleep 9 hours or more. Sleep patterns may be genetically influenced. When two researchers, Wilse Webb and Scott Campbell, checked the pattern and duration of sleep among fraternal and identical twins, only the identical twins were strikingly similar.
(2) Whatever their normal need for sleep, some 10 to 15 percent of adults complain of insomnia - persistent problems in falling or staying asleep. True insomnia is not the occasional inability to sleep that we experience when anxious or excited. For a stressed organism, alertness is natural and adaptive. Moreover, from middle age on, sleep is seldom uninterrupted. Occasional awakenings become the norm, not something to fret over or treat with medication.
(3) Sometimes people fret unnecessarily about their sleep. Scientists have learned to doubt people's fretful sleep reports. In laboratory studies, insomnia complainers do get less sleep than others, but they typically overestimate, by about double, how long it took them to fall asleep, and they underestimate by nearly half how long they actually slept. Even if we've been awake only an hour or two, we may think we've had little sleep. because it's the waking part we remember. When researchers awaken people repeatedly during the night, some recall having slept soundly.
(4) The most common quick fixes for true insomnia - sleeping pills - can aggravate the problem. Both reduce REM sleep and can leave a person with next-day blahs. With continued use, one needs bigger doses to get an effect, and when the drug is discontinued, the insomnia may worsen. Scientists are searching for natural chemicals that are abundant during sleep and might be as a sleep aid without side effects. In the meantime, sleep experts offer other natural alternatives:
• Relax before bedtime, using dimmer light.
• Avoid caffeine (this includes chocolate) after late afternoon and avoid rich foods before bedtime. A glass of milk may help. (Milk provides raw materials for the manufacture of serotonin, a neurotransmitter that facilitates sleep.)
• Sleep on a regular schedule (rise at the same time even after a restless night) and avoid naps. A regular sleep schedule boosts daytime alertness, too, as shown in a recent experiment in which University of Arizona students slept 7.5 hours a night on either a varying or consistent schedule
• Exercise regularly but not in the late evening. (Late afternoon is best.)
• Reassure yourself that the temporary loss of sleep causes no great harm, certainly nothing worth losing sleep over.
• If nothing else works, aim for less sleep; go to bed later or get up earlier.
(5) More rare but also more severe than insomnia are the sleep disorders narcolepsy and sleep apnea. People with narcolepsy (from narco, "numbness, "and lepsy," seizure") suffer periodic, overwhelming sleepiness. This usually lasts less than 5 minutes but sometimes occurs at the most inopportune times, perhaps just after taking a terrific swing at a softball or when laughing loudly or shouting angrily. In severe cases, the person may collapse directly into a brief period of REM sleep, with its accompanying loss of muscular tension. Those who suffer from narcolepsy - 1 in 2000 people, estimates the Stanford University Center for Narcolepsy - must live with extra caution.
(6) The National Heart, Lung, and Blood Institute reports that 1 in 25 people (mostly overweight men) suffer from sleep apnea - a treatable disorder that was unknown before modern sleep research. They intermittently stop breathing during sleep. (Apnea means "stopping respiration”) After an airless minute or so, decreased blood oxygen arouses the sleeper to awaken and snort in air for a few seconds. The process can repeat more than 400 times a night, depriving the person of slow-wave sleep. Apart from complaints of sleepiness and irritability during the day - and their friends' complaints about their loud "snoring"- apnea sufferers are often unaware of their disorder.

How many people suffer from narcolepsy?

Sleep Disorders اضطرابات النو م
(1) The idea that "everyone needs 8 hours of sleep" is untrue. Newborns spend nearly two-thirds of their day asleep, most adults no more than one-third. Age. related differences in average time spent sleeping are rivaled by differences in the normal amount of sleep among individuals at any age. Some people thrive with fewer than 6 hours of sleep per night; others regularly sleep 9 hours or more. Sleep patterns may be genetically influenced. When two researchers, Wilse Webb and Scott Campbell, checked the pattern and duration of sleep among fraternal and identical twins, only the identical twins were strikingly similar.
(2) Whatever their normal need for sleep, some 10 to 15 percent of adults complain of insomnia - persistent problems in falling or staying asleep. True insomnia is not the occasional inability to sleep that we experience when anxious or excited. For a stressed organism, alertness is natural and adaptive. Moreover, from middle age on, sleep is seldom uninterrupted. Occasional awakenings become the norm, not something to fret over or treat with medication.
(3) Sometimes people fret unnecessarily about their sleep. Scientists have learned to doubt people's fretful sleep reports. In laboratory studies, insomnia complainers do get less sleep than others, but they typically overestimate, by about double, how long it took them to fall asleep, and they underestimate by nearly half how long they actually slept. Even if we've been awake only an hour or two, we may think we've had little sleep. because it's the waking part we remember. When researchers awaken people repeatedly during the night, some recall having slept soundly.
(4) The most common quick fixes for true insomnia - sleeping pills - can aggravate the problem. Both reduce REM sleep and can leave a person with next-day blahs. With continued use, one needs bigger doses to get an effect, and when the drug is discontinued, the insomnia may worsen. Scientists are searching for natural chemicals that are abundant during sleep and might be as a sleep aid without side effects. In the meantime, sleep experts offer other natural alternatives:
• Relax before bedtime, using dimmer light.
• Avoid caffeine (this includes chocolate) after late afternoon and avoid rich foods before bedtime. A glass of milk may help. (Milk provides raw materials for the manufacture of serotonin, a neurotransmitter that facilitates sleep.)
• Sleep on a regular schedule (rise at the same time even after a restless night) and avoid naps. A regular sleep schedule boosts daytime alertness, too, as shown in a recent experiment in which University of Arizona students slept 7.5 hours a night on either a varying or consistent schedule
• Exercise regularly but not in the late evening. (Late afternoon is best.)
• Reassure yourself that the temporary loss of sleep causes no great harm, certainly nothing worth losing sleep over.
• If nothing else works, aim for less sleep; go to bed later or get up earlier.
(5) More rare but also more severe than insomnia are the sleep disorders narcolepsy and sleep apnea. People with narcolepsy (from narco, "numbness, "and lepsy," seizure") suffer periodic, overwhelming sleepiness. This usually lasts less than 5 minutes but sometimes occurs at the most inopportune times, perhaps just after taking a terrific swing at a softball or when laughing loudly or shouting angrily. In severe cases, the person may collapse directly into a brief period of REM sleep, with its accompanying loss of muscular tension. Those who suffer from narcolepsy - 1 in 2000 people, estimates the Stanford University Center for Narcolepsy - must live with extra caution.
(6) The National Heart, Lung, and Blood Institute reports that 1 in 25 people (mostly overweight men) suffer from sleep apnea - a treatable disorder that was unknown before modern sleep research. They intermittently stop breathing during sleep. (Apnea means "stopping respiration”) After an airless minute or so, decreased blood oxygen arouses the sleeper to awaken and snort in air for a few seconds. The process can repeat more than 400 times a night, depriving the person of slow-wave sleep. Apart from complaints of sleepiness and irritability during the day - and their friends' complaints about their loud "snoring"- apnea sufferers are often unaware of their disorder.

What percentage of adults have problems falling asleep?