The most common sleep disorder is Insomnia, which affects around 35% of all adults in any given year. Insomnia is indicated by a difficulty in attaining sleep, or a difficulty in remaining asleep. Many people who wake up numerous times during the night are insomniac; the effect of insomnia is the inability of the sleep cycle to properly relax and heal the body and mind. Insomnia cures range from folk remedies like warm milk to pharmaceutical remedies like morphine; many chemical remedies allow unconsciousness, but prevent the body from attaining full relaxation.
Another major sleep disorder is Narcolepsy, or the sudden and unexpected shift from wakefulness to sleep. This can be extraordinarily dangerous for the sufferer because of the varied circumstances in which it can strike; narcoleptics have often fallen asleep when operating heavy machinery or performing sports. Like insomnia, narcolepsy can be treated with both folk and chemical stimulants; the chemical stimulants are safer here as they promote attention and focus, but, ironically, can often interfere with normal sleeping habits.
One disorder that affects over 6% in the United States is Sleep Apnea, or the temporary halting of breathing functions. This can be caused by asthma, obesity, drug interactions, or biological issues such as excess mucus production or tumor growth. Sleep apnea is usually not fatal -- at least not immediately -- but can cause both physical and mental health problems. Some sufferers of sleep apnea become depressed because their brains are not receiving enough oxygen to properly recover; others suffer actual brain damage, and some die. Apnea treatments are usually effective, ranging from breathing masks to surgery to chemical remedies.