ALBUQUERQUE, New Mexico – Her car is racing at a terrifying speed through the streets of a large city, and something gruesome, something with giant eyeballs, is chasing her, closing in fast.

It was a dream, of course, and after Emily Gurule, a 50-year-old high school teacher related it to Dr. Barry Krakow, he did not ask her to unpack its symbolism. He simply told her to think of a new one.

“In your mind, with thinking and picturing, take a few minutes, close your eyes, and I want you to change the dream any way you wish,” said Krakow, founder of the PTSD Sleep Clinic at the Maimonides Sleep Arts and Sciences centre here and a leading researcher of nightmares.

And so the black car became a white Cadillac, travelling at a gentle speed with nothing chasing it. The eyeballs became bubbles, floating serenely above the city.

“We call that a new dream,” Krakow told Gurule. “The bad dream is over there” – he pointed across the room – “and we’re not dealing with that. We’re dealing with the new dream.”

The technique, used while patients are awake, is called scripting or dream mastery and is part of imagery rehearsal therapy, which Krakow helped develop. The therapy is being used to treat a growing number of nightmare sufferers. In recent years, nightmares have increasingly been viewed as a distinct disorder, and researchers have produced a growing body of empirical evidence that this kind of cognitive therapy can help reduce their frequency and intensity, or even eliminate them.

The treatments are controversial. Some therapists, particularly Jungian analysts, take issue with changing nightmares’ content, arguing that dreams send crucial messages to the waking mind.

Nightmares are important because they “bring up issues in bold print,” said Jane White-Lewis, a psychologist in Guilford, Connecticut, who has taught about dreams at the Carl Jung Institute in New York.

While White-Lewis acknowledged that she does not treat patients suffering from severe trauma, she said that if a nightmare is eliminated, “you lose an opportunity to really get some meaning out of it.” Changing eyeballs into bubbles, she added, might have robbed Gurule of the chance to find out what the eyeballs were trying to tell her.

Nightmares have fascinated and perplexed people for centuries, their meaning debated by therapists and analysts of all schools of thought, their effects so powerful that one terrifying nightmare can affect a person for a lifetime.

A nightmare is “a disturbing dream experience which rubs, bites and sickens our soul, and has an undercurrent of horsepower, lewd demons, aggressive orality and death,” White-Lewis wrote in “In Defense of Nightmares,” her contribution to a 1993 book of essays about dreams.

From 4 percent to 8 percent of adults report experiencing nightmares, perhaps as often as once per week or more, according to sleep researchers. But the rate is as high as 90 percent among groups like combat veterans and rape victims, Krakow said. He said treatment for post-traumatic stress needed to deal much more actively with nightmares.

He and other clinicians are increasingly using imagery rehearsal therapy, or IRT, to treat veterans and active-duty troops in the Iraq and Afghanistan wars.

Last month, Krakow conducted a workshop on imagery rehearsal and other sleep treatments for 65 therapists, sleep doctors and psychiatrists, including many working with the military. And the technique has drawn more attention from other researchers in the past several years. Anne Germain, an associate professor of psychiatry at the University of Pittsburgh School of Medicine, is comparing two treatments – behavioural therapy, including imagery rehearsal, and the blood-pressure drug prazosin, which has been found to reduce nightmares.

Preliminary results from a study of 50 veterans showed that both treatments were effective in reducing nightmares and symptoms of PTSD, she said, although they differed from patient to patient. She is continuing to study what factors may lead to those differences.

Deirdre Barrett, a psychologist at Harvard Medical School who is an expert on dream incubation, inducing dreams to resolve conflicts, and on the connection between trauma and dreams – said she was struck by the growing interest in nightmares as a result of war trauma and torture.

“Within the community of psychologists who have put an emphasis on dreams it used to be about interpretation,” she said. “And now therapists are getting the message that you can influence dreams, ask dreams about particular issues and change nightmares.”

Krakow’s nightmare therapy typically includes four sessions of group treatment and between one and 10 individual sessions, although Krakow said between three and five sessions are usually effective. (The clinic visits are covered by insurance.)

Krakow’s latest research which was presented last month at the annual meeting of the Associated Professional Sleep Societies, found a striking connection between PTSD and a variety of sleep disorders. In an analysis of the sleep studies conducted on more than a thousand patients with varying degrees of post-traumatic stress, he found that five to 10 other sleep problems may be involved. High rates of sleep apnoea, for example, were found even in patients with moderate symptoms of post-traumatic stress. “In the world of PTSD and sleep, no one is making these connections,” Krakow said.

He refers to his small clinic, in an office park here, as a “bed-and-breakfast without the breakfast.” It has four small bedrooms, with pastel-coloured bedspreads and cheerful, serene paintings of fish and beaches. Before bed, the technicians place sensors on the patients to track sleep, breathing and movement.

Krakow, 61, started out as an internist and then practiced emergency medicine before studying nightmares and possible treatments with colleagues at the University of New Mexico in the late 1980s. With financing from the National Institute of Mental Health, he conducted his first major research between 1995 and 1999, looking at the effect of imagery rehearsal on 168 sexual assault survivors who suffered from nightmares.

The results of a randomized controlled trial were published in a 2001 paper in the Journal of the American Medical Association. Of the subjects, 95 per cent had moderate to severe PTSD, 97 per cent had experienced rape or other sexual assault, 77 per cent reported life-threatening sexual assault and 58 per cent reported repeated exposure to sexual abuse in childhood.

The treatment group, 88 women, participated in three sessions of imagery rehearsal therapy, while the control group, 80 women, was on a waiting list and continued with whatever treatment they had been undergoing. Of the 114 that completed follow-up at three or at three and six months, those in the treatment group had “significantly” reduced the nights per week with nightmares and the number of nightmares per week, the paper said. The control group showed small, “nonsignificant” improvement on the same measures. And symptoms of post-traumatic stress decreased in 65 per cent of the treatment group, while they either remained unchanged or worsened in the control group, according to the findings.

Along with other researchers, Krakow has continued to publish further studies on imagery rehearsal, finding that of hundreds of patients treated, about 70 per cent have reported significant improvements in nightmare frequency after regularly using the treatment for two to four weeks.