Практическое занятие №6

ТЕМА 6  Sleep Disorders


According to the American Psychiatric Association, sleep disorders are major disturbances of normal sleep patterns that lead to distress and disrupt functioning during the day. Not only are sleep disorders extremely common, affecting virtually everyone at some point in their lives, but they can also lead to serious stress and other health consequences.

According to a major survey by the National Sleep Foundation, more than half of Americans reported experiencing at least one symptom of insomnia several times a week during the previous year. Highlighting another major danger of sleep disorders, the survey also reported that 60 percent of respondents had driven while drowsy during the previous year.

Insomnia:

Insomnia is by far the most common sleep disorder, affecting nearly 60 percent of U.S. adults at least one night each week. Common symptoms of insomnia include difficulty getting to sleep and waking before it is time to get up. There are many factors that can contribute to insomnia including stress and underlying medical conditions. Typical treatments include sleeping pills and behavior therapy. Practicing good sleep habits can often be effective for treating mild cases of insomnia.

Sleep Apnea:

Sleep apnea is the second most common sleep disorder and affects approximately 20 million Americans. This disorder causes people to stop breathing abruptly while they are asleep. During this brief period, carbon dioxide builds up in the blood and the sleeper wakes suddenly to gasp for breath. The length of time that the sleeper stop breathing can vary from a few seconds to so long that the individuals skin actually turns blue from oxygen deprivation.

Sleepwalking & Night Terrors:

While insomnia and sleep apnea are more common in adults, other sleep disorders such as sleepwalking and night terrors are far more common in young children. Sleepwalking, also known as somnambulism, is characterized by periods of getting out of bed while asleep.

Night terrors are most frequently seen in very young children (between the ages of 2 and 6), but people of any age can be affected by this sleep disorder. Typical symptoms include excessive sweating, shaking and obvious fear.

What Is Narcolepsy?

Excessive Sleepiness May Be Due to Neurologic Condition Narcolepsy is a neurologic condition that results in excessive daytime sleepiness and other symptoms due to a failure to regulate the states of sleep and wakefulness. This failure results in abrupt transitions from one state into the other. This may lead to sudden weakness while awake (called cataplexy) or even complete paralysis, as would normally occur to prevent a person from acting out her dreams.

Unfortunately, when this occurs at inappropriate times it may cause injury. Additionally, people with narcolepsy may experience intense hallucinations while transitioning to sleep (called hypnagogic hallucinations) as the brain generates dreams while the narcoleptic remains awake. Although only one in three people with narcolepsy will have all four symptoms, these four defining features are characteristic of the disorder. Cataplexy is not known to occur in any other disorder, so its presence is very helpful in identifying narcolepsy as the cause of the other symptoms.


How Common is Narcolepsy?

Narcolepsy was first described by the French physician Jean Gelineau in 1880. It is now thought to affect about 1 in 2,000 people. The symptoms of narcolepsy usually begin in the teens or early twenties, but it may rarely first occur in children or even the elderly. It affects men as commonly as women.
There may be some ethnic variation, as it is quite uncommon among Israeli Jews (with a prevalence of only 0.002%) and occurs relatively frequently among the Japanese (with a prevalence of 0.15%). A study of 18,000 people in five European countries found an estimated prevalence of 0.047%.
There may be a genetic component to the disorder as narcolepsy can be more commonly found among relatives of people with the disorder. However, the environment seems to have an important role as well (only 25 percent of identical twins will both have the disorder).
What Causes Narcolepsy?
Narcolepsy appears to occur because of a loss of the chemical hypocretin in an area of the brain called the hypothalamus. The nerve cells (or neurons) in the brain that rely on this chemical regulate sleep and alertness. Hypocretin is thought to promote wakefulness and maintain normal muscle tone, so it makes sense that its loss would lead to the sudden weakness seen in cataplexy.
It is thought that the body's immune system, which typically is responsible for fighting infection, may turn against the hypocretin-containing neurons. In narcoleptics, studies have shown that 85 to 95 percent of these neurons are lost. When these cells are damaged, there are frequent, inappropriate transitions between sleep and wakefulness. Narcolepsy may also be caused by rare lesions within the brain that result because of tumors, strokes, or other insults.
Diagnosis and Treatment of Narcolepsy
If you believe you may be suffering from narcolepsy, it is important to speak with your doctor and a sleep specialist. After a careful evaluation and examination, you may need to undergo other testing to establish the diagnosis of narcolepsy. In general, these tests will include an overnight sleep study called a polysomnogram and a study the next day called a multiple sleep latency test (MSLT).
In addition, there may be laboratory tests (including a genetic test). If your sleep studies are negative but there is still a strong suspicion for narcolepsy, it may be important to test your cerebrospinal fluid for the chemicals orexin and hypocretin.
There is no cure for narcolepsy, but treatments may help to alleviate some of the symptoms. Excessive daytime sleepiness may be alleviated with stimulants such as Ritalin, Provigil, and Nuvigil. A medication called sodium oxybate can effectively treat the sleepiness as well as cataplexy.
If you have narcolepsy, it is best to review the treatment options with your physician to ensure that the appropriate medication is selected to manage your particular symptoms.

Fill in the gaps in the sentences with the appropriate words from the box
Alertness (1); hypothalamus (5); alleviate (6); cataplexy (3); sleep disorder (4); neurons (7); lesions (2);
1. The nerve cells (or neurons) in the brain that rely on this chemical regulate sleep and … .
2. Narcolepsy may also be caused by rare … within the brain that result because of tumors and strokes.
3. Hypocretin is thought to promote wakefulness and maintain normal muscle tone, so it makes sense that its loss would lead to the sudden weakness seen in … .
4. Night terrors are most frequently seen in very young children (between the ages of 2 and 6), but people of any age can be affected by this … … .
5. Narcolepsy appears to occur because of a loss of the chemical hypocretin in an area of the brain called the … .
6. There is no cure for narcolepsy, but treatments may help to … some of the symptoms.
7. In narcoleptics, studies have shown that 85 to 95 percent of these … are lost.