I meet Kirk, one of the participants, two months after his high-dose session. Kirk had been depressed, particularly since his mother’s death three years ago. He experienced entrenched thought patterns, like going round and round on a racetrack of negative thoughts, he says. “I wasn’t as motivated, I wasn’t doing as much, I wasn’t exercising any more, I wasn’t as social, I was having anxiety quite a bit. It just deteriorated. I got to the point where I felt pretty hopeless. It didn’t match really what was going on in my life. I had a lot of good things going on in my life. I’m employed, I’ve got a job, I’ve got family, but really it was like a quagmire that you sink into.”

At the peak of the drug experience, Kirk was deeply affected by the music. He surrendered himself to it and felt overcome with awe. When the music was sad, he would think of his mother, who had been ill for many years before her death. “I used to go to the hospital and see her, and a lot of the time she’d be asleep, so I wouldn’t wake her up; I’d just sit on the bed. And she’d be aware I was there and wake up. It was a very loving feeling. Quite intensely I went through that moment. I think that was quite good in a way. I think it helped to let go.”

During the therapy sessions, there were moments of anxiety as the drug’s effects started to take hold, when Kirk felt cold and became preoccupied with his breathing. But he was reassured by the therapists, and the discomfort passed. He saw bright colors, “like being at the fun fair”, and felt vibrations permeate his body. At one point, he saw the Hindu elephant god Ganesh look in at him, as if checking on a child.

Although the experience had been affecting, he noticed little improvement in his mood in the first 10 days afterwards. Then, while out shopping with friends on a Sunday morning, he felt an upheaval. “I feel like there’s space around me. It felt like when my mum was still alive, when I first met my partner, and everything was kind of OK, and it was so noticeable because I hadn’t had it in a while.”

There have been ups and downs since, but overall, he feels much more optimistic. “I haven’t got that negativity any more. I’m being more social; I’m doing stuff. That kind of heaviness, that suppressed feeling has gone, which is amazing, really. It’s lifted a heavy cloak off me.”

Another participant, Michael, had been battling depression for 30 years, and tried almost every treatment available. Before taking part in the trial, he had practically given up hope. Since the day of his first dose of psilocybin, he has felt completely different. “I couldn’t believe how much it had changed so quickly,” he says. “My approach to life, my attitude, my way of looking at the world, just everything, within a day.”

One of the most valuable parts of the experience helped him to overcome a deep-rooted fear of death. “I felt like I was being shown what happens after that, like an afterlife,” he says. “I’m not a religious person and I’d be hard pushed to say I was anything near spiritual either, but I felt like I’d experienced some of that, and experienced the feeling of an afterlife, like a preview almost, and I felt totally calm, totally relaxed, totally at peace. So that when that time comes for me, I will have no fear of it at all.”