People can be divided into many groups: those who believe in God and those who don't; those who agree with capital punishment and those who don't. The significance of dreams is another such issue, separating those who believe their dreams - and nightmares - are meaningful from those who don't.

The latter group weighs in with the scientific community and its explanation for dreams: that they are our brains' internal processing of life, without any intrinsic meaning. The former group - into which the author, psychotherapist and hypnotherapist Alex Lukeman places himself - believes dreams are full of meaning and an important form of communication between the unconscious and conscious parts of our minds.

Based in Fort Collins, Colorado, Lukeman was in Dublin last week to promote his new book, Nightmares: How To Make Sense Of Your Darkest Dreams. "It is helpful to understand your dreams. They are a source of wisdom, an untapped resource, and I believe it is worthwhile to make the effort to understand them. They can give you a valuable and practical guide to life," says Lukeman. "Nightmares warn us that we are caught up in some internal conflict needing resolution for the sake of our well-being."

Sixty this year, Lukeman has a gentle, compassionate demeanour. He pursued various career paths, including those of professional musician and Rolf practitioner, before settling into pyschotherapy and dreams. This book is his third on the subject, preceded by What Your Dreams Can Teach You and Sleep Well, Sleep Deep.

A near-death experience in 1975 changed the direction his life was taking and drew him towards the study of psychology and alternative health therapies.

In Nightmares, he identifies universal dream themes such as spiders and snakes, running for your life, the death of a loved one, choking, drowning and suffocation. He discusses their generic interpretation and also recounts real-life dreams with explanations of their significance to the dreamer.

Snakes, for example, can symbolise wisdom and self-knowledge, sexuality or evil and untrustworthiness, depending on the dreamer and the context. Dreams about rape or attack are associated with victimisation, relationship problems, feelings of helplessness, self-criticism turned inwards or feelings of sexual inadequacy or frustration.

"It's not a formula. Symbols can mean different things to different people. The purpose of dreams is to get your attention, then you've got to figure out the implication of the message. It takes a lot of practice," he says.

"If you are being chased by men in dark suits, it probably has to do with work-related stress. If you understand the message, then you can do something about it. If not, you may get recurring or worse nightmares," says Lukeman.

He notes that Irish people have the same kind of dreams as Americans, but says he has noticed one cultural difference. "A lot of people are trying to get a goal in football in their dreams, which is symbolic of trying to succeed," he says. "I have also been told that if you eat cheese before you go to bed, you will have a nightmare. This is simply not true, although it isn't a good idea to eat a lot of food before going to bed."

And to those sceptics who believe their dreams are nonsense, he says: "most people think their dreams are nonsense until they begin to read the symbols. Dreams don't follow the ways of communication that we are used to."

Although not a Jungian therapist, Lukeman admits he has been deeply influenced by the Swiss psychoanalyst Carl Jung and his theories on dreams. But what about people who don't dream?

"Of course they dream. They just don't remember their dreams. Maybe they are too tired or are in poor health. Maybe they had a traumatic event in their childhood or had a series of nightmares as a child and decided they didn't want to dream."

Lukeman says a mistranslation of a passage in "Leviticus", the third book of the Bible, condemned dreams and categorised them as influenced many devout religious people.

Speaking about children and their bad dreams, Lukeman says it is helpful to get children to talk about their nightmares and to reassure them that they are only dreams. "It is the parent's job to do something to help them feel back in control. For example, to role-play the dream and have the child play the superhero."

As we get older, he adds, the content of nightmares shifts and deepens. "For teenagers, the most common theme of nightmares is about relationships: losing their friends, losing their boyfriend or girlfriend. Then, as adults, we become more aware of the dangers of the world and have dreams that are linked to dealing with our roles in life."

To work with our dreams, Lukeman suggests we record them, with a Dictaphone or paper and pen, as soon as we wake up, then read them later. And to nurture your dream-time, he offers the usual advice on healthy living. "Get enough sleep. Sleep regular hours, eat reasonably well and live your life with as much balance and comfort as possible."

Following a few busy days feeding the Irish media machine, Lukeman has headed for Co Clare for a few days of calm. Once back in the US, however, the publicity machine for his next book will begin to crank up. Called Dreams From The Other Side, it sounds as if it will see Lukeman move farther into mysterious waters. "I believe people who have died can bring messages of comfort and hope in the dreams of loved ones," he says, frankly.

Nightmares: How To Make Sense Of Your Darkest Dreams by Alex Lukeman is published by Newleaf, £9.99 in UK. See also www.alexlukeman.com