For years, the field of mental health has been largely barren of meaningful treatment advances. But now, scientists have new hope in the least likely of places: psychedelic drugs. Recent research suggests that certain psychedelic substances can help relieve anxiety, depression, PTSD, addiction and the fear surrounding a terminal diagnosis.

“The biggest misconception people have about psychedelics is that these are drugs that make you crazy,” says Michael Pollan, author of the new book How to Change Your Mind: What the New Science of Psychedelics Teaches Us About Consciousness, Dying, Addiction, Depression, and Transcendence. “We now have evidence that that does happen sometimes — but in many more cases, these are drugs that can make you sane.”

In the interview below (and video above), Pollan talked with TIME about the therapeutic promise of the drugs, their fraught history and the sheer terror he felt after smoking toad venom.

Walk me through a brief history of psychedelics.

If you ask people about psychedelics or LSD, they’re going to think about the psychedelic ’60s — Timothy Leary, this flamboyant psychology professor who was at Harvard for a few years, studying psilocybin and LSD, and then telling everybody they should take it in a very public way. The drugs kind of escaped the laboratory and were embraced by the counterculture.

The result was a full-scale moral panic against the drugs. President Nixon said Timothy Leary was the most dangerous man in America, which is pretty amazing for a washed-up psychology professor. But before that, there had been more than a decade of very promising research using these drugs in a therapeutic context in a very responsible way.

What do psychedelics do to the human mind?

The honest answer: nobody quite understands. We’re really just at the beginning of exploring that frontier. But psychedelics appear to diminish activity in one very important brain network called the default mode network. That network is very involved with operations having to do with our sense of self: how we integrate what’s happening to us in any given moment, with our abiding sense of who we are.

The interesting thing about psychedelics, both LSD and psilocybin — the ingredient in magic mushrooms — is that they take this network offline. When that happens, you have this sensation of ego-dissolution: that your self is evaporating or dissolving. And that seems to lead to new connections in the brain temporarily forming. Your emotion center starts talking directly to your visual cortex, let’s say, and you see things that you’re hoping or fearing. New connections are made that could produce new insights, new perspectives, new ways of looking at the world.

Your book talks a lot about the scientific approach to psychedelics. What do scientists believe that psychedelics can offer people?

The feeling among the scientists is that these chemicals allow us to essentially reboot the brain. If the brain is stuck in these narrow grooves of thought — whether it’s an obsession or a fear or the story you tell yourself — all those deep grooves that lock us into patterns of both thought and behavior are dissolved and temporarily suspended in a way that allows us to break those patterns.

What psychedelics do you think show some therapeutic potential?

There are two drugs that show the most potential and will probably be legalized for medical use soon. One is a drug that isn’t always considered a psychedelic: MDMA, also known as Ecstasy or Molly, which has been shown to be incredibly useful in the treatment of trauma, including post-traumatic stress disorder (PTSD) in soldiers or in rape victims. A study recently came out that showed great effectiveness at treating those problems. That’s very encouraging, and that may be the first of these drugs to get approved.

The second is psilocybin. It appears to be very useful in the treatment of anxiety, depression and addiction in both smoking and alcohol.

MORE: I Took A Psychedelic Drug for My Cancer Anxiety. It Changed My Life

Well, it’s important to remember that when psilocybin is used in a medical and healing context, it’s very different than the recreational use of the drug. This isn’t doctors giving you a pill and sending you out into the world. For a period of four or five hours, you are in a room that’s decorated like a cozy den or study. You’re lying down on a couch, you have eye shades on and headphones, which are playing a very carefully curated playlist to make you go inside to have an internal experience. And you’re with two guides at all times, who are there looking out for your interests. It’s an incredibly safe environment in which to let down your defenses, and that’s essentially what happens.

All of our customary defenses that we use to deal with life and the world will be suspended for a period of time, and that creates this opening, this plastic moment where people can reexamine themselves and get some perspective on their habitual ways of thinking and doing.

Then, you come out of this experience, which can be very difficult for some people. It’s not all fun and games. Some people are put in touch with childhood traumas, some people have encounters with death — it can be very dark.

But with the help of the guides, you use that material and try to understand it. After the session, you always come back the next day and have what’s called a period of integration, where the guides, who are trained therapists, help you interpret what happened and figure out ways to put it to good use in changing your life.

How do some people change after taking psilocybin in clinical trials?

One of the big questions about this is: what endures from this experience? One of the interesting studies they did when they crunched the data on the first groups of people who had had a guided psilocybin session was that these were adults, but one of their personality traits that psychologists call openness — openness to other people’s views, openness to new experience, openness to new ideas — increased. To find an actual measurable change in personality as adults is a very unusual finding. Normally, our personalities are fixed by the time we’re in our 20s. But here was a very positive aspect of personality that could change and did change.

You tried various psychedelics for the book. Tell me about your best journey. What did it feel like?

My best was a fairly high-dose psilocybin journey that I had with a guide, a woman in her 50s who was a very skilled therapist and who worked in other modalities as well. I had to work with someone illicitly, and I learned that there is a thriving underground of psychedelic therapists. These are serious professionals, but they are doing something illegal.

What was stunning about it was I had an experience of complete ego-dissolution. I reached a point where my “self” just kind of fell apart into these little pieces of paper. I saw myself get scattered to the wind, but I was all right with it. I didn’t have any urge to stack the papers back up together. Then I looked out; I saw myself spread over the landscape as a coat of paint. And I was fine with it.

The consciousness that was perceiving all of this was not my usual ego. It wasn’t upset or defensive or trying to do anything. It was dispassionate, objective. And I learned a really important lesson in that moment, which is that I’m not identical to my ego. My ego is one of a couple of characters in my mind, and not always the best. The ego is very important — the ego got the book written. But it’s also what punishes us, what keeps us locked in our grooves of thought, and it’s what defends us against the world and against our own consciousness.

What was your worst journey?

My worst journey was on this psychedelic called 5-MeO-DMT, which is the venom of the Sonoran Desert Toad. Apparently you can milk the toad repeatedly and kind of squeeze the glands on its side or its arm onto a sheet of glass. It dries overnight and looks like brown sugar crystals. Then you smoke it, and it’s instantaneous. Before I even exhaled, I felt like I’d been shot out of a rocket.

I had not only the experience of ego-dissolution, but the dissolution of everything: of my body, of any kind of perceiving consciousness, of material reality. It was all gone. It was just a pure Category 5 storm of energy, and I didn’t know where I was in it. I felt like I was in the middle of an atomic blast or in a world before the Big Bang, when there was only energy and not yet matter. These are metaphors that don’t begin to capture how horrifying it was. I thought this could be death — this could be what it’s like to leave your body, because I had lost my body.

The best thing about this trip is it only lasted about 15 minutes. After a period of time, I felt a perceiving “I” kind of come back. And then I could feel my body. I was like, wow! This is so great, I have a body, and then there’s a floor. And there’s stuff that’s back — matter is back. I ended with this incredible feeling of gratitude such as I’d never felt — not just for my own existence, not just for life, but for anything, that anything exists, that there is something rather than nothing. So I guess that’s a valuable takeaway, but I had to go a long way to have it. And I wouldn’t wish that experience on anybody.

Did you feel your personality changed after trying these drugs?

I kind of feel like I went back to baseline. My wife thinks it’s changed in some ways. Not in a profound way, but I think she would say that I’m more open and more patient, that I deal with emotional situations with a little more availability.

I think she may well be right. Simply spending this much time observing my mind and having experiences where I got to sneak up on it in various ways does have an effect. It’s the same effect that 10 years of psychoanalysis probably would have, although it didn’t take me nearly that long.

How do psychedelics bring together the worlds of science and spirituality?

We often think about science and spirituality as these opposed terms, but in fact a lot of this research is forcing scientists to deal with spiritual questions, and some spiritual people to deal with scientific questions, which is very exciting.

The very first study in the modern era of psychedelic research, of any importance, was a 2006 study done at Johns Hopkins by a scientist named Roland Griffiths, a very prominent drug-abuse scientist. He found that what the psychedelics did in about 80% of cases was induce a mystical experience, which is a spiritual experience that was studied closely by William James 100 years ago. It has various aspects to it. Prominent among them is this dissolving of a sense of self, but that is followed by a merging with the universe, or with nature, or other people. It’s called the noetic sense — this sense that what you’re seeing or feeling or learning on this experience has the status of revealed truth. It’s not just an opinion — it’s objectively true.

We see this experience all over religious literature: people who have had an experience of meeting with the divine. These traits are common, and the fact that you could induce such a spiritual experience with a single administration of a drug was quite remarkable. These people reported that this experience was one of the top two or three in their lives, comparable to the birth of a child or the death of a parent. Now that we can actually induce a spiritual experience using a drug, we can study the phenomenon.

How has the experience of writing this book changed your mind about death?

It made me more curious and a little less afraid. I wouldn’t say it eliminated my fear, and I wasn’t trying to do that, but I was able to kind of look at it with this equanimity.

On this psilocybin trip, I saw the faces of people close to me who had died over the last few years. You understand why traditional cultures would take plant medicines to reconnect with the dead. You can see them and talk to them and they can talk to you. I’m not saying this is a supernatural phenomenon. It’s a psychological phenomenon — at least that’s how I understand it. It made people who were gone more present in my life, and I’m happy for that. I wrote this book during a period when my dad was dying. He had terminal cancer, and I dedicated this book to him before he died.

One of the things the psilocybin research is doing is helping open that conversation — to make people more comfortable talking about it, to get patients to actually deal with it. Oncologists don’t do a very good job of that, and we have very little for the treatment of the psychology of people who are dying. So a drug that takes you into these spiritual realms where you can begin to think it through seems to me an enormous gift.

What role are psychedelic drugs going to play in your life going forward?

I don’t know if they’ll play any role moving forward. I had the experiences I needed to have. I met people who have a psychedelic experience once a year on their birthday, and that seemed about right, to do that sort of stock-taking. But the drugs are illegal, and now I’m out talking about it publicly, so that option has been closed to me until they’re made legal.

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