Hypnosis doesn't work for everybody. For those who are susceptible, however, it has successfully alleviated an amazing range of symptoms, including those of asthma, allergy, stroke, multiple sclerosis, Parkinson's disease, cerebral palsy, and irritable bowel syndrome. It can control nausea and vomiting from cancer medications, reduce bleeding during surgery, steady the heartbeat, and bring down blood pressure. It has helped some people lose weight, controlled severe morning sickness in others, and given many relief from muscle spasms and even paralysis.

Stanford Hypnotic Susceptibility Scales: This test requires you to complete 12 exercises that range from closing your eyes and falling forward (or backward) to imagining your hand to be so heavy that you can't hold it up (or lift it). The last couple of exercises test your response to "posthypnotic suggestions." You might, for example, find yourself changing chairs spontaneously whenever the therapist taps his fingers after the test. Most people can perform the first few exercises; only a few can do them all. The farther you get, the greater your chances of being hypnotized.

Barber Suggestibility Scale: This battery of exercises is similar to the Stanford Scales, but includes only 8 tasks. For example, you may have to imagine that you are extremely thirsty; or you may be expected to respond with a spontaneous cough every time the therapist makes a clicking sound after the test. Again, the more tasks you can complete successfully, the better a candidate you are for hypnosis.

Harvard Group Scale of Hypnotic Susceptibility: Like the Stanford Scales, this test includes 12 exercises, but is given to a group. Since the presence of other people can prove distracting, it is not considered as reliable a predictor as the other two.

Other ways of measuring your susceptibility for hypnosis include:

The eye-roll test: In this exercise, you'll first be asked to open your eyes wide, then roll them up. Then you'll have to lower your eyelids without rolling your eyes down. Ability to complete these tasks is not, however, a fool-proof predictor of your ability to be hypnotized.

The light test: You may also be asked to stare at a small spot of light in a dark room. While most people are convinced the light is moving, those who see it change directions most frequently are supposedly the best subjects for hypnosis.

The lemon test: Some therapists ask first-time patients to imagine looking at, feeling, picking up, and slicing a lemon in half. They must then picture themselves squeezing some of the juice into a container, smelling it, and drinking a little. Those who are aware of salivating after performing the exercise once (or, in some cases, more than once), are more likely to be good candidates than those who do not salivate more than usual.

After the testing, the therapist will discuss the medical or psychological condition you wish to work on, as well as any other goals you may have in mind. This helps the therapist determine the approach to use during your upcoming sessions.

When therapy begins, you'll be asked to remove all jewelry and other accessories that may distract you and lie on a reclining chair or couch. There are several techniques the therapist can use to put you into a "hypnotic trance." The most common are:

• Asking you to watch a moving object as it swings back and forth, then suggesting in a monotonous, soothing voice that your eyes are getting so heavy you can't keep them open.
• Telling you to concentrate on the therapist's voice as he gives you instructions.
• Having you count backward slowly from 30 to 0.

   As you slip into the trance, you'll feel deeply relaxed. Your conscious mind will no longer control every thought and emotion as it does when you are "awake." Your surroundings will become less important as you become increasingly aware of your inner feelings and sensations. At this point, you will be asked to stop thinking "consciously" and concentrate on something that will make you feel peaceful, such as walking through the woods or watching a sunset. With all troubles, pains, and other negative thoughts cleared from your mind, you'll find yourself able to focus intently on the instructions the therapist gives you.

Now, the therapist may make suggestions. He may tell you how you can make an unwanted symptom or habit disappear. For example, if you have pain in your stomach, you may be told to visualize the pain as a small fish and then to imagine a shark snatching the fish and swimming away with it. With the fish gone, the therapist may suggest, you will be pain-free when you awake.

Analytical hypnotists use a technique called "regression." While you are in a relaxed "trance" state, the therapist will ask you to recall buried memories or emotions that may have caused your problem. (This is an accepted therapeutic technique when limited to your conscious life. Be alert, however, for mystics who promise to prod you into "remembering" events that happened in your mother's womb, or say they can regress you to a "past life" that supposedly occurred generations--or even centuries--ago. Whatever this may be, it's not therapy.)

The therapist may also implant posthypnotic suggestions while you are in the trance. You may be asked to remember or forget something or behave a certain way in response to a given signal after you awaken. For example, you may be told to feel nauseated every time you hear the sound of a cigarette lighter or see a certain type of food. Or the therapist may suggest you ignore a pain after you come out of the trance.

At the end of the session, the hypnotist will suggest how you should feel afterward and will order you to wake up. You may feel normal right away, or you may be sleepy for a few hours. Even if the hypnotist were to leave you alone, you would not remain in a trance. After slipping into a natural sleep, you would wake up by yourself.

To reinforce your treatment, the therapist will also teach you self-hypnosis. (You can learn this technique from audio and videotapes, but most professionals strongly urge that you take lessons from a qualified hypnotherapist.)

When performing self-hypnosis, sit or lie in a quiet, comfortable place, such as your favorite chair. Then try to relax completely, letting all your muscles go limp and allowing all tension to flow away.

To induce the hypnotic "trance," or focused state of mind, you can imagine yourself walking down a long path or descending a long staircase; concentrate on an object and breathe slowly and deeply; count backward from 10 to 0; tell yourself over and over that your eyes are heavy, your limbs are numb, or your face is warm or cool; or repeat a word or phrase.

Once you have achieved a hypnotic state, tell yourself how you want to feel, or listen to a tape on which you have recorded the message. To wake up, count slowly upward from 0 to 10, or reverse the image you used to put yourself under--for example, walk up the staircase. Tell yourself you will awaken feeling wonderful.

Treatment Time: Sessions with a hypnotherapist usually last from 60 to 90 minutes. Self-hypnosis sessions typically take 20 to 30 minutes.

Treatment Frequency: Most people see the therapist once a week. Proponents of self-hypnosis suggest you hypnotize yourself every day.

Although "trances" may sound like psychological hocus pocus, they are neither mysterious nor unfamiliar to most of us. We have all daydreamed or become lost in a novel. Sometimes we concentrate so deeply on a problem that we drive right past our exit on a highway. In all such cases, we are in a sort of trance--a state of "focused concentration" in which we are neither fully awake nor fully asleep. We have blocked out all distractions so that we can think exclusively on a particular subject, memory, problem, or sensation.

The concept of using trances to alleviate ills, both physical and mental, has recurred throughout the history of medicine. The ancient Greeks and Egyptians induced trance-like states to cure what we would call anxiety and hysteria. The Druids called trances "magic sleep." Native Americans and Africans recognized the hypnotic effect of drumming and dancing.

Modern hypnotherapy got a false start in the 18th century, when Austrian physician Franz Anton Mesmer propounded his theory of "animal magnetism." Believing that illness was a result of imbalance in the body's magnetic forces, he insisted that he could restore balance--and thus cure diseases--by transferring magnetism from his body to his patients. He endeavored to achieve this by waving iron rods, magnets, and his hands in front of his subjects and using "soothing words" to induce a trance. His influential contemporaries branded him a charlatan, and his magnetic theory was soon discarded.

Interest in the healing potential of the trance was later resurrected by James Braid, an English ophthalmologist, who coined the term "hypnosis," after the Greek word for sleep. To induce a trance, Braid simply stared at his subjects intently. Although he realized he could implant ideas in his subjects while they were in this deep, relaxed state, he could not explain why this was so.

Hypnosis remained in vogue until the late 19th century, and Freud used it in his early work. It then fell out of favor once again, resurfacing in the 1950s when Milton Erickson began experimenting with it for the treatment of both mental and physical ailments. By 1955 the British Medical Association had approved hypnotherapy as a valid medical treatment; the American Medical Association (AMA) followed suit in 1958. Today, the therapy is so widely accepted that the American Society of Clinical Hypnosis, a professional association of physicians, psychologists, and dentists, boasts 4,300 members.

While there seems to be little doubt that hypnosis provides lasting benefits for many of those who try it, no one is quite certain of the reason. Some scientists speculate that it prompts the brain to release chemicals called enkephalins and endorphins, natural mood-altering substances that can change the way we perceive pain and other physical symptoms. The majority, however, feel that it acts through the unconscious, the part of the mind responsible for involuntary reactions ranging from blood pressure and heart rate to hunger. Normally, these reactions are beyond our control. Hypnotherapy seems to put them under our power.

Whatever the truth of the matter, it's clear that when you are in a relaxed, trance-like state, you are receptive to suggestions that can help you react differently to negative situations, turn your attention away from harmful or unpleasant stimuli such as pain, discourage unwanted behavior, and even change your pulse rate or body temperature. The technique can also put you in touch with memories that may explain the origins of current problems and habits. Once you understand why you act a certain way, proponents suggest, you're in a better position to change the way you respond. Your mind can focus on productive solutions and hopefully overcome negative reactions.

One of hypnotherapy's greatest benefits may be its ability to reduce the effects of stress. Many physicians and psychologists believe that the mind has a direct impact on physical well-being. According to this theory, tension, anxiety, and depression can undermine immunity and compromise your health, while a positive attitude can reinforce the immune system, enabling it to better fight infections, toxins, and other invaders. Hypnosis can allay stress by putting you into a relaxed state, offering positive suggestions, and ridding the mind of negative thoughts. As tension in your muscles--and even your blood vessels--recedes, the theory goes, your circulation then improves, and your entire body feels healthier.

Fortunately, the truth of the matter is that the hypnotist is never in control. A hypnotic suggestion works only if you accept it, and the therapist cannot make you do something you would not do consciously, something that goes against your moral code or religious beliefs, for example. The practitioner's goal is to help you use your own mind to solve problems, rather than give you the answers.

To find such a therapist, ask your physician for a reference or contact one of the following organizations. (See addresses and telephone numbers below.)

• American Council of Hypnotist Examiners
• American Institute of Hypnotherapy
• American Society of Clinical Hypnosis
• International Medical and Dental Hypnotherapy Association
• Milton H. Erickson Foundation
• National Guild of Hypnotists

   Before beginning therapy, it's also a good idea to spend an hour or so with the practitioner to determine whether you have a good rapport.

Likewise, even though it works with the mind, hypnosis is not the best choice for many psychological problems, which are now known to be caused by chemical imbalances in the brain. It is not recommended, for instance, as a treatment for psychosis, severe depression, or antisocial behavior.