Disruptive sleep-related disorders are called parasomnias. They are undesirable physical or veral behaviors or experiences that people have that are associated with sleep or the sleep-awake transition phase.

There are two phases of parasomnias. The primary and the secondary phases are the two different categories of parasomnias. Primary parasomnias are those that are disorders of sleep states and are classified according to the stage of sleep in which they originate. Secondary parasomnias are disorder of other systems that happen during sleep such as the person having seizures, respiratory difficulty, arrhythmias (abnormal heart rhythms) or gastroesophageal reflux.

There are different parasomnias but the most common of the disorders are nightmare disorder, sleep terror disorder, sleepwalking, REM sleep behavior disorder, restless legs syndrome (RLS), and periodic limb movement disorder (PLMD).

Nightmare disorder may also be referred to as dream anxiety attack. Children often suffer from nightmare disorder. These nightmares occur during the REM sleep stage and are associated with an increase in heart rate or tachycardia and an increase in the rate at which the person is breathing. The individual may sweat profusely and may or may not remember the night terror when he/she awakes.

Sleep terror involves a sudden, loud or terrified scream while asleep followed by activities such as hitting objects, moving in and out of the bedroom, and may involve injuring themselves. This is a disturbance of the third or fourth stage of sleep.

Sleepwalking disorder is when individuals wander aimlessly around, carry objects, go outdoors, and perform activities even driving while asleep. They usually cannot communicate but may mumble while asleep. This disturbance occurs during the slow-wave stage of NREM sleep.

REM sleep behavior disorder is when individuals act out what they are dreaming, which may include talking, yelling, punching, kicking, sitting, jumping out of bed, and arm movements.

Restless legs syndrome and periodic limb movement disorder are also common disorders that happen sometimes with the same person and can cause excessive daytime sleepiness.

Causes of Sleep Disorders:

The nightmare disorder can be caused by personality disorders, relationship difficulties, and various stresses of life. Certain drugs can also cause nightmare disorder such as beta-adrenergic drugs, and going through withdrawal of REM-suppressing medications.

The causes for sleep terror disorder may be that the person has a fever, has had a period of sleep deprivation such as interns working multiple shifts at the hospital, and CNS depressant drugs.

Sleepwalking disorder may be hereditary or run in families. Some drugs such as lithium, desipramine, chloral hydrate, thiroridazine and fluphenazine can also cause sleepwalking disorder. A person with a fever may also have this happen. Sometimes sleep deprivation or obstructive sleep apnea can lead to sleepwalking disorder or even something as simple as a full bladder.

REM sleep behavior disorder has no known cause.

Restless legs syndrome and periodic limb movement disorders also have no known cause.