MOre on REM Behavior Disorder

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REM BEHAVIOR DISORDER

Sleep is a dynamic process consisting of two basic states: Rapid Eye Movement (REM) and non-Rapid Eye Movement (non-REM) sleep. These two basic states are as different from each other as sleep differs from wakefulness.

Non-REM sleep is divided into four stages, numbered 1 through 4 (1= the lightest/ drowsiness, and 4=the soundest). In all these non-REM states, the brain is relatively inactive and the body is relatively active (our muscle tone is maintained).

In contrast, REM sleep is just the opposite in some respects. Our brain is very active-this state is that from which we recall our most vivid dreams. To keep us from acting out those dreams (which could be dangerous particularly when our dreams are violent) we become limp and paralyzed. Of course, if we stay asleep, we don't even know that we become paralyzed.

We must cycle back and forth between these two types of sleep repeatedly during any given night of sleep-usually some four or five times. Normal people start with progressively deeper stages of non-REM sleep, and then have their first period of REM sleep only after some ninety minutes of non-REM sleep have occurred, after which they have more non-REM sleep, followed by yet another REM period. This cycling between non-REM and REM sleep continues until final awakening. Each successive REM period tends to be longer than those that preceded it, so we get most of our REM sleep during the last part of our sleep. In contrast, most of our deeper stages of non-REM sleep occur during the first third of the night.

REM-related symptoms can occur for two basic reasons:

REM sleep occurs too early.

The component parts of REM sleep (the vivid dreaming and paralysis) don't stay "glued together" as they should and parts of REM sleep intrude into wakefulness, where they don't belong.

Although the consequences are usually harmless, they often are very frightening. For example: while it's not so bad to be paralyzed in sleep when you don't even know about it, to experience sudden paralysis when awake is "the pits".

What are these specific REM-related symptoms?

-REM sleep occurs too early.

Vivid dreaming in brief naps, or the immediate onset of dreaming after falling asleep. When these symptoms truly reflect the premature onset of REM sleep, they can represent symptoms of such disorders as narcolepsy and sleep apnea, and can also be caused by withdrawal from medicines or other substances, such as alcohol, that suppress REM sleep. Withdrawal of "REM suppressants" can be followed by a "REM rebound".

-Dream fragments occur at times when the person is not fully asleep.

The individual may begin watching a vivid dream while still hearing his or her surroundings, or instead hear the "sound track of a dream" when not fully asleep. In other cases, the person may feel things that aren't there (rain on one's forehead, the sensation of a rat running across one's leg, etc.). These hallucinations are called hypnogogic hallucinations when they precede sleep onset and hypnopompic hallucinations when they occur immediately after awakening. They often seem real to the point of causing terror or fears that one is losing one's mind. They can arise from narcolepsy, withdrawal from REM suppressants, and occasionally from such other causes as sleep apnea and severe sleep deprivation.

-The paralysis of REM sleep intrudes into wakefulness--which can cause two different problems:

Sleep paralysis. The person suddenly notes complete inability to move or call out for help either when first dozing off or upon first awakening. The sensation is much like being buried alive! However, it is transient, harmless and can be broken by being touched (which is small comfort when one cannot call out for help!). This phenomenon can arise from the same causes as hypnagogic hallucinations. Sleep paralysis also can occur as a rare event in otherwise normal individuals.

Cataplexy. This is the only symptom that is diagnostic of narcolepsy in sleepy individuals (although not all patients with narcolepsy develop cataplexy). Cataplexy refers to triggering of the limp paralysis that should only occur in REM sleep instead by emotions during wakefulness. Upon experiencing a humorous event, laughing, encountering an old friend or when experiencing other emotions as excitement during athletic competition or anger, the person with cataplexy experiences waves of muscle weakness that may cause sagging of the face with inability to speak, bobbing of the head, dropping things, or buckling of the knees. In severe cases, the individual may even experience total collapse with falling and complete paralysis, but with maintained consciousness. The attack may last only seconds. However, some seriously afflicted patients can remain in a totally helpless state for a half-hour or longer. While these attacks can be mistaken for blackouts or seizures, they are simply the result of one component part of REM sleep occurring at the wrong time.

-Paralysis fails to develop in REM sleep when it should.

The consequence? The individual able to act out dreams, sometimes with serious injury to self or others--particularly when the dreams have a violent content. In some cases, the individual may even attack his or her bed partner during dreams of struggling with an intruder who has entered the home. Some deaths have resulted.

This condition, REM Behavior Disorder (RBD) has been described most frequently in men over age 60, some of whom also demonstrate other disorders of the brain. It is a neurologic, not a psychiatric disorder, and often a potentially dangerous one that can and should be treated. It sometimes can be triggered by sleep apnea. It also can occur in younger individuals and women, some of whom will be found to have narcolepsy.