Types of Sleep

The two types of normal sleep are slow wave and rapid eye movement (REM). Slow-wave sleep (also called non-REM sleep) occurs when a person is very tired, and it reflects decreasing activity of the reticular formation. It is restful, dreamless, and accompanied by reduced blood

Disorder

Symptoms

Percent of Population

Fatal familial insomnia

Inability to sleep, emotional instability, hallucinations, stupor, coma, death within thirteen months of onset around age fifty, both slow-wave and REM sleep abolished.

Very rare

Insomnia

Inability to fall or remain asleep.

10%

Narcolepsy

Abnormal REM sleep causes extreme daytime sleepiness, begins between ages of fifteen and twenty-five.

0.02-0.06%

Obstructive sleep apnea syndrome

Upper airway collapses repeatedly during sleep, blocking breathing. Snoring and daytime sleepiness.

4-5%

Parasomnias

Sleepwalking, sleeptalking, and night terrors outgrown.

<5% of children

REM-sleep behavior disorder

Excessive motor activity during REM sleep, which disturbs continuous sleep.

Very rare

Restless-leg syndrome

Brief, repetitive leg jerks during sleep. Leg pain forces person to get up several times a night.

Very rare

Sleep paralysis

Inability to move for up to a few minutes after awakening or when falling asleep.

Very rare

pressure and respiratory rate. Slow-wave sleep may range from light to heavy and is usually described in four stages. It may last from seventy to ninety minutes. Slow-wave and REM sleep alternate.

REM sleep is also called "paradoxical sleep" because some areas of the brain are active. As its name implies, the eyes can be seen rapidly moving beneath the eyelids. Cats and dogs in REM sleep sometimes twitch their limbs. In humans, REM sleep usually lasts from five to fifteen minutes. This "dream sleep" is apparently very important. If a person lacks REM sleep for just one night, sleep on the next night makes up for it. During REM sleep, heart and respiratory rates are irregular. Certain drugs, such as marijuana and alcohol, interfere with REM sleep. Table 11.6 describes several disorders of sleep.

The person to go the longest without sleep was a seventeen-year-old student who stayed awake, in a sleep laboratory under medical supervision, for 264 hours. Fortunately, he suffered no ill effects, but during his ordeal, he was irritable and had blurred vision, slurred speech, and memory lapses. Toward the end, he seemed confused about his identity.

Rats experimentally deprived of sleep do not fare as well. In a study conducted at the University of Chicago, rats kept awake by a moving floor developed skin sores and hormonal and metabolic changes, dying within eleven to thirty-two days. Control rats allowed to nap survived.

U What are the major functions of the thalamus? Of the hypothalamus?

How may the limbic system influence a person's behavior?

Which vital reflex centers are located in the brain stem? What is the function of the reticular formation? Describe two types of sleep.

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