JASON O'Callaghan has had quite a career. Following a stint in the Merchant Navy, the Dublin man made his name as a showbiz journalist with The Sunday Independent before taking to the stage himself by masterminding The Irish Rat Pack, a Sinatra and co tribute act which became a hit wedding band throughout Ireland.
However, in 2008, Walkinstown-born O'Callaghan returned to university to study psychology, earning a master's degree in Applied Psychology from Trinity College and making the roll of honour for his research into the effectiveness of hypnosis as a means of reducing stress and anxiety in cancer patients.
He also trained in clinical hypnotherapy, Cognitive Behaviour Therapy (CBT) and counselling, and volunteered for over four years in the mental health sector.
O'Callaghan (44) currently divides his time between practising clinical hypnotherapy at The D4 Clinic in Dublin– where he helps clients to overcome a variety of problems from smoking and weight loss to gaining confidence, overcoming phobias and getting a good night's sleep – and performing his popular stage hypnosis act as 'The Victorian hypnotist' (more about which in a moment) at weddings and corporate events.
"I paid my way through college as a musician," he explains.
"When I graduated and I started to do hypnosis more and more, I sort of trained myself to do stage hypnosis as a hobby for corporate and entertainment work.
"But stage hypnosis is completely different from clinical hypnosis. Primarily I'm a psychologist, that's my day job.
"At my clinic in Dublin I specialise in smoking, weight loss, selective eating disorder, insomnia – psychological issues that we use behavioural therapy for such as hypnosis, aversion therapy, cognitive behaviour therapy, mindfulness."
Indeed, if you have been struggling with any of the aforementioned issues, hypnotherapy could help – but you'd best pay close attention to the D4 Clinic disclaimer: 'Willpower may be required and individual results may vary.'
"Everyone will react to hypnotherapy differently – as with any therapy, from chemotherapy to counselling to medication," advises O'Callaghan.
"And, at the end of the day, there is no therapy in the world for any addiction that helps people to quit anything without them really wanting to quit.
"Whether it's cigarettes or alcohol or whatever, only once you want to quit can you work with a therapist to help you quit."
Having recently made the news by helping a fear-of-flying crippled man get to his American honeymoon with an impromptu five minute hypnotherapy session at Gatwick airport, O'Callaghan has also worked with clients at The D4 Clinic to overcome some unusual eating habits.
"I treated one girl who was living on potato waffles and we helped her overcome that," he tells me.
"I had another guy in who couldn't eat meat – he wasn't vegetarian, he wanted to eat meat, but had just developed an aversion to it."
It seems some food-related problems are more difficult to overcome than others, particularly when it comes to curbing poor eating habits.
"Weight-loss is the hardest," O'Callaghan explains.
"We've had a lot of success with people who've lost five, six, seven stone, and that's great. But we also have a lot of people who just come in here, pay money and don't do anything at all. They don't even listen to their hypnosis at home."
Indeed, just as simply paying for a gym membership won't keep you fit, hypnotherapy is only effective as a weight loss strategy when subjects keep working at their problem.
O'Callaghan's clients must commit to regular 'homework' sessions where they regularly review personally tailored hypnotherapy videos.
"What we do at the clinic is charge people a once-off fee of €300 and we never charge them again," he tells me.
"It doesn't matter how often they need to come back in – thankfully a lot of people stop after one session, but some need two or three or four and need extra support.
"But with weight-loss, the only condition we put on them is that they have to lose five pounds between sessions. There's no point just coming back here having done nothing, so every time they lose five pounds they can come back in with no extra charge."
Hypnotherapy alone may not be enough to overcome certain issues – other forms of clinical treatment may also be required in order to achieve the desired results.
"As a psychologist, there's a whole toolbox I can use," explains O'Callaghan.
"Some people might need more counselling, some people might need more hypnotherapy, some might need just a chat.
"But the confidence that you as a therapist can give somebody just by letting them know that nothing bad is going to happen when they put their trust in you – you can help them change after just one session."
It seems that with hypnotherapy and hypnosis in general, only one thing is truly certain.
"Hypnosis is only effective on people who want to be hypnotised," he advises, pointing out that the people you see being hypnotised during stage shows are all effectively self-selecting – they volunteer to be 'put under'.
"It just depends on people's mindset. Only a certain percentage of people are highly suggestible – and you can't hypnotise people who don't want to be hypnotised. That's why you never have to be worried or scared of it."
As mentioned, Jason O'Callaghan is billed as 'the Victorian hypnotist' for his stage performances thanks to his revival of an "aggressive" hypnosis technique banned in the 19th century to prevent unscrupulous charlatans taking advantage of people.
He explains: "It skips the whole progressive induction, counting backwards from 20 etc, in favour of a much more aggressive method. It involves mind control, in a way – you can put your finger in front of someone and they'll just fall over.
"There's only one other guy who can do it, Justin Tranz – that's his real name – in America. He trained with (famous hypnotist) Pat Collins, and then I trained with him last year. I'm the only Irish person trained to do it.
"It's not dangerous, just hard to do – and very exciting."
However, it's helping people beat their problems using clinical techniques which offers this showman and psychologist most satisfaction at the current stage of his colourful career.
"Helping people with smoking is my number one thing, because I'm very anti-smoking," enthuses O'Callaghan.
"It helps to save people's lives."
:: Find Jason online at D4Clinic.ie and JasonOCallaghan.com