JASON O'CALLAGHAN
D4 Psychology & Hypnotherapy Clinic
(Hypnotherapy, Counselling, Mindfullness and CBT)
The D4 Clinic provides a complete range of hypnotherapy services, from in-clinic sessions and online appointments to VIP intensives and instant-access downloadable programmes, ensuring there’s an approach to suit every individual.
Open daily from 9am to 8pm.
Irelands TOP Google ranked Hypnotherapy Clinic
As seen on
About Jason O'Callaghan
Hello, I'm Jason O'Callaghan.
Member of the Psychology Society of Ireland
M.Ps.S.I. (Membership No M13886)
Since 2012, I’ve helped thousands of people across Ireland create lasting change through evidence-based clinical hypnotherapy, psychology, counselling, CBT, and mindfulness.
If you’re looking for a trusted hypnotherapist to help with anxiety, stress, confidence, or unwanted habits, you’re in the right place. Many clients come to us feeling stuck or overwhelmed, and leave with clarity, calm, and renewed control.
At the D4 clinic our programs mixing clinical hypnotherapy, counselling, CBT and mindfulness to focus on real transformation by addressing the root causes behind what’s holding you back. You can work with us in person at our Blackrock clinic, through personalised hypnotherapy audio programmes, or via downloadable bundles you can use anytime.
My research in clinical hypnotherapy has been published by the Mayo Clinic in the United States. In 2013 I was named on the Trinity College role of honour for my work using therapy with cancer patients. I hold a honours degree in psychology plus a masters degree in applied psychology from Trinity College Dublin. I also hold qualifications from Maynooth University in counselling and the IICP in Dublin in CBT. I also hold national diploma in media and spent 10 years working within the Irish media at the highest level. I have appeared as an expert on ITV’s This Morning, 2FM, Newstalk, and TG4, as well as speaking at major international hypnotherapy conferences.
If you’re ready to make a positive change with a proven hypnotherapist, get in touch with The D4 Clinic today and begin your path to a calmer, more confident life.
Together, we can create the change you’re ready for so you can feel calmer, clearer and more in control.
What I can do for you
- Help you reduce anxiety, manage stress and feel more in control through personalised clinical hypnotherapy and psychological techniques
- Break unwanted habits such as overeating, smoking, vaping or negative thinking patterns with structured, evidence-based strategies
- Improve confidence, focus, sleep and emotional wellbeing using an approach grounded in psychology, CBT, mindfulness and counselling
- Provide VIP intensive sessions for clients who want deeper support or faster results
- Give you clear, practical tools you can use every day to stay calmer, more resilient and more motivated
- Offer flexible options that fit your lifestyle including in-clinic sessions, personalised hypnotherapy audio programmes and downloadable bundles
- Bring over a decade of experience, Mayo Clinic-published research and specialist training from Trinity College Dublin to help you make meaningful and lasting change
Although hypnotherapy results cannot be guaranteed, you can rely on my clinical experience, professionalism and commitment to helping you achieve the best possible outcome.
Latest Reviews from Google
EXCELLENT
Based on 170 reviews
Posted on Google![]()
Katie MaloneTrustindex verifies that the original source of the review is Google.
I went with a phobia and had such a lovely and warm experience with Jason. It was like going to a lovely spa experience or deep meditation class. I felt really relaxed & empowered after our session, thank you Jason! Would absolutely recommend.Posted on Google![]()
claire maloneTrustindex verifies that the original source of the review is Google.
Jason is great at what he does. He’s so easy to deal with too.. makes you feel very at ease. Highly recommend 🙌🏻Posted on Google![]()
Darren ElliottTrustindex verifies that the original source of the review is Google.
I had a brillant session today with jason and it has giving me so much clarity moving toward my goals that i can achieve anything i have my mind set on so thanks very much to Jason.Posted on Google![]()
Orla Mc DonnellTrustindex verifies that the original source of the review is Google.
I honestly can’t recommend Jason enough! For over 10 years, I hadn’t tried any new foods because my mind would immediately tell me, “I don’t like that,” and I would feel sick at the thought of trying something different. I was extremely fussy — you could probably count everything I ate on two hands! After just one session with Jason, something completely changed. He helped me realise that I could try new foods without that automatic negative reaction. Straight after the session, I ate a strawberry, a protein yoghurt and a Fulfil bar — all things I had never tried before — and I had absolutely zero issues. I just naturally tried them and realised that I actually liked two of them! For someone who hadn’t tried a new food in over a decade, that feels absolutely huge. I’m so glad I decided to go to Jason. The difference after just one session has honestly amazed me. Absolute 10/10 experience, and I would highly recommend him to anyone struggling with something similar. Thank you so much, Jason!Posted on Google![]()
Kevin ShoreTrustindex verifies that the original source of the review is Google.
I had my first hypnosis session yesterday and was genuinely really impressed. I went in slightly sceptical and wondering whether hypnosis would actually work on me, but the experience was completely different to what I expected. It’s quite difficult to describe, but I definitely reached an incredibly deep state of relaxation while still being aware of everything that was happening. I left the session feeling more relaxed than I have in a very long time. This was only my first of six sessions, so I’m really interested to see how things progress from here, but based on my first experience I’d absolutely recommend giving it a try, particularly if, like me, you’re unsure whether hypnosis will work for you.Posted on Google![]()
Mark DTrustindex verifies that the original source of the review is Google.
I found my first hypnotherapy session with Jason calming and relaxing. He fully explained the process beforehand which enabled me feel comfortable and at ease. Thank you Jason and I look forward to continuing.Posted on Google![]()
Mark KeoghTrustindex verifies that the original source of the review is Google.
What can i say, was skeptical when i booked but even after the first session i could feel the differences, will definitely be back to work on some other issues.Posted on Google![]()
Paula KellyTrustindex verifies that the original source of the review is Google.
I had a really positive experience working with Jason. From the first session, he made me feel comfortable, less anxious & more relaxed. The sessions were calm, professional and tailored to what I needed each session depending on the level of anxiety etc. I’ve noticed a real improvement since starting and I feel more positive and equipped with the tools. I wouldn’t hesitate to recommend Jason to anyone who is considering hypnotherapy and is looking for a welcoming supportive and professional approach.Posted on Google![]()
Barry WalshTrustindex verifies that the original source of the review is Google.
I've seen it all — the kind of things that harden you and make you think you can handle anything. But there was one deeply personal issue I'd carried for years that nothing else could touch. It affected my sleep, my focus, and my peace of mind in ways I couldn't fully explain. Jason O'Callaghan is the real deal. Extremely professional, no-nonsense, and highly skilled, he created a safe space and used hypnosis and psychological techniques tailored to me. He helped me finally understand and resolve something that had been weighing me down for so long. The difference is night and day. I feel clearer, lighter, and back in control. If you're carrying something heavy that conventional approaches haven't fixed, I highly recommend Jason. He's helped me more than I expected Thank you JasonPosted on Google![]()
Feargal KellyTrustindex verifies that the original source of the review is Google.
I found Jason's sessions to be very helpful in managing stress levels and facing life challenges with greater resilience. I would have no hesitation in recommending his service to others. Many thanks.Verified by TrustindexTrustindex verified badge is the Universal Symbol of Trust. Only the greatest companies can get the verified badge who has a review score above 4.5, based on customer reviews over the past 12 months. Read more
Our Treatments
Anxiety Hypnotherapy
Blushing Hypnotherapy
Break Your Relationship with Food Hypnotherapy
Claustrophobia Hypnotherapy
Deep Sleep Hypnotherapy
Dentist Visit Anxiety Hypnotherapy
Fear of Clowns Hypnotherapy
Fear of Flying Hypnotherapy
Gambling Addiction Hypnotherapy
Instant Confidence Hypnotherapy
Junk Food Addiction Hypnotherapy
Nail Biting Hypnotherapy
Nicotine Gum Dependency Hypnotherapy
Procrastination Hypnotherapy
Public Speaking Hypnotherapy
Reduce Alcohol Habit Hypnotherapy
Social Anxiety Hypnotherapy
Stop Vaping Hypnotherapy
Stress and Anxiety Hypnotherapy
Sugar Dependancy Hypnotherapy
Success Stories
Many thanks for your help at D4 clinic. I have now lost over 3 stone and feel so good. This picture of me is in my first pair of size 12 jeans in over 20 years. It is just amazing how it has worked. I now love my daily walk.Thanks again for all your help. I would have no hesitation in recommending the D4 CLINIC to my friends and colleagues.