Read the text and find out the cause of sleep disorders.

What is it? A sleep disorder is a brain disorder. The brain regulates sleep and is the only organ known to require or benefit from sleep. There are more than 100 sleep disorders affecting about 40 million Americans. Most sleep disorders are very common and can be treated. Unfortunately, 95 percent of these disorders are never diagnosed.

The nature of sleep. Several processes in your body control how sleepy or alert you are. The two most important processes are “homeostatic” and “chronobiologic.”The homeostatic process controls how long you stay awake. The longer we are awake, the greater the pressure is for us to fall asleep. The chronobiologic process determines our sleep cycles. Each of us has a “biologic clock” that follows the changes of daylight to darkness.

Other things that affect sleep are age, medications, diet, and environmental conditions.

Sleep/wake cycles are determined primarily by genetics and physical needs. Most people require 7 to10 hours of sleep per day. You may be a “lark” (“early to bed, early to rise”) or an “owl” (“late to bed, late to rise”).

Children and teenagers require 9 to 10 hours of sleep. However, teens have a biologic tendency to delay falling asleep as long as possible. With aging, most people tend to go to sleep earlier and their sleep is less intense. This often means waking earlier than is desirable.

Major sleep disorders. The International Classification of Sleep Disorders lists approximately 100 known sleep disorders. Most sleep complaints fall into one of these categories:

· Hypersomnia

· Obstructive Sleep Apnea Syndrome

· Narcolepsy

· Idiopathic Central Nervous System Hypersomnia

· Insomnia

· Circadian Rhythm Disturbances

Hypersomnia. Hypersomnia is extreme sleepiness during the day even with adequate sleep the night before. Hypersomnia has been mistakenly blamed on depression, laziness, boredom, or other negative personality traits.

Obstructive Sleep Apnea. Sleep apnea is a breathing disorder where you briefly wake up because your breathing has been interrupted. This often results in snoring. There are two types of sleep apnea: central and obstructive.

Central sleep apnea is less common and occurs when the brain fails to send the right signals to the muscles to start breathing.

Obstructive sleep apnea (OSA) is far more common. It occurs when air cannot flow into or out of the person’s nose or mouth as they breathe.

As many as 18 million Americans have sleep apnea. OSA is as common as asthma or diabetes. It is experienced by both sexes, all age groups and in people who do not snore. The high incidence of OSA in children is just becoming known.

Narcolepsy. Narcolepsy causes uncontrollable sleepiness. It affects one in 1, 000 people. Many people with narcolepsy have other symptoms such as:

· Cataplexy: Sudden muscle weakness caused by emotional events. For example, falling when you hear terrible news.

· Sleep paralysis: Waking up to find your body is paralyzed except for breathing and eye movement. In other words, your brain is awake but your body is still asleep.

Hypnogogic hallucinations: Frightening dreams as you are falling asleep. Idiopathic Central Nervous System Hypersomnia. This condition causes excessive sleepiness as its only symptom. Excessive sleepiness is also a symptom of another sleep disorder called narcolepsy – but narcolepsy has other symptoms as well.

Insomnia. Insomnia is ongoing difficulty in falling asleep, staying asleep, or restless sleep. Technically, insomnia is a symptom of a sleep disorder. Chronic insomnia is common and affects 15 - 20 percent of adults. Occasional trouble sleeping is not insomnia.

Circadian Rhythm Disturbances. Circadian rhythm disturbances occur when sleep/wake cycles are interrupted. They often affect shift workers whose biological clocks are disrupted by conflicting sleep and work schedules. People who take long plane trips may experience “jet lag.” This is another form of circadian rhythm disburbance.