In the past century of surgical anesthesia practice, the ideal outcome has been to have the patient remember absolutely nothing from the surgery, not even a sliver of a dream. A total blackout.

But in the past couple of decades, as anesthesia techniques have become more precise, anesthesiologists have noticed that some patients recall pleasant dreams as they emerge from anesthesia at the end of surgery.

In recent years, Stanford Medicine researchers have intentionally promoted dreaming during anesthesia and documented several cases in which the experience dramatically improved the mental health of patients who had suffered for years with post-traumatic stress disorder. Their dreams, usually populated by friends and family, reimagined stressful events with more peace. Afterward, their symptoms resolved, and nightmares that had plagued them nightly disappeared.

To some, these cases suggest a therapeutic opportunity hiding on the edges of the total blackout. Boris Heifets, MD, PhD, associate professor of anesthesiology, perioperative and pain medicine, sees parallels between anesthesia dreams and the transformative experiences many people have with MDMA, commonly known as ecstasy, as well as psilocybin, ketamine, and ibogaine. These psychoactive substances have gained interest as a potential new class of psychiatric therapies, though how they work is unclear.

Now, Heifets and collaborators – including neuroscientists, psychiatrists, and anesthesiologists – have validated a five-step protocol that can safely and reliably induce dreaming in patients emerging from anesthesia. In a study published in July in the journal Anesthesiology, the team found that among 452 patients who underwent the dreaming protocol during elective surgery, 69% reported dreaming. Their dreams were almost always pleasant – with 86% describing them as positive or somewhat positive.

The lead author of the study is Pilleriin Sikka, PhD, a research scientist in anesthesiology, perioperative and pain medicine. Heifets is senior author. He developed the project with Harrison Shong-Wen Chow, MD, clinical associate professor of anesthesiology, perioperative and pain medicine, who made the initial observations of potentially therapeutic anesthesia dreaming.

The dreaming protocol has five steps:

1. Telling the patient they might dream under anesthesia.
2. Using propofol as the anesthetic as the patient is emerging from anesthesia.
3. Monitoring brain activity and guiding the emergence via electroencephalogram, or EEG.
4. Ensuring at least 10 minutes of quiet, undisturbed emergence.
5. Immediately asking about dream recall upon awakening.

The protocol does not affect the standard anesthesia process during surgery, Heifets emphasized, nor does it increase intraoperative awareness. It’s a slow, intentional tapering at the end of surgery, like tuning the brain into a dream-state radio station.

The most difficult step, which was not achieved for most of the patients, turned out to be maintaining 10 minutes of quiet in a busy operating room. For a group of 57 patients who had 10 minutes of undisturbed emergence, the dreaming rate jumped to 93%.

We spoke with Heifets about the potential of dreaming under anesthesia, the parallels and differences with psychedelics, and how it challenges current mental health approaches.

Now that you’ve developed this reliable protocol, what are the benefits of dreaming under anesthesia?

There are two big directions we would like to take. One is we could systematically improve the experience of tens of thousands of patients undergoing surgery, an event that is often associated with fear and anxiety. With this pretty simple protocol, we can induce pleasant dreams, and that could reduce health care hesitancy. Patients who recalled dreaming reported better sleep quality under anesthesia than patients who didn’t.

The other direction: Maybe anesthesia dreaming could fall under the broader umbrella of rapid-acting therapies for psychiatric disease alongside ketamine, psilocybin, MDMA, ibogaine, and others. It basically follows the same structure: Patients have a profound experience that results in this impressive mental health recovery.

How do you go about studying this as a potential psychiatric therapy?

We’ve taken this out of the operating room and are studying anesthesia dreaming in people who are not undergoing surgery. We conducted a study of healthy patients that we’re writing up. In a couple of months, we’ll be done with our first open-label trial (in which all patients receive the dreaming protocol) with 15 patients with moderate to severe PTSD – the results so far are promising. Then we’ll do a randomized blinded trial (in which there’s a control group) with PTSD patients.

We’re deploying this as a mental health intervention that borrows deeply from psychedelic work. We do some preparation with a licensed therapist right before anesthesia who does what’s called image rehearsal therapy – the patient reimagines an aspect of their trauma, such as a trigger or a nightmare, with a better ending. We don’t want to trigger the trauma directly, but it brings the association to mind right before they go to sleep.

If you find that anesthesia dreaming can have similar effects as psychedelic treatments, what does that tell us about how psychedelics work?

The broader work we’re engaged in is trying to understand how things like psychedelic therapy work. Is it the drug? Is it the trip? Is it something biochemical? Is it the overall context of care?

This anesthesia dreaming work shows we’re able to reproduce psychedelic-like experiences with a drug that’s not a psychedelic. We’re getting similar subjective experience, similar physiology, and similar therapeutic outcomes with propofol, which is not a psychedelic. To me, it screams that the experience itself, in this case the trip, is critical and has very little to do with the underlying drug that is used. This needs further work, obviously, but it’s a strong suggestion that it is the subjective experience itself that is so crucial.

We also did an earlier study in people with depression where we gave some people ketamine and others placebo during anesthesia. Both groups got better. Even though they didn’t experience a trip in that case because they were unconscious, there was still an overall care experience. It suggests that the context of care has some power – we told them they’re in a study, we paid attention to them, we listened to them, and they put in effort to seek out treatment. I can virtually guarantee those same things are also at work in psychedelic trials and are often attributed to the drug when, in fact, they’re baked into the methods of the trial itself.

What’s the alternative theory and why does the difference matter?

There’s a camp that says the experience doesn’t matter and it’s biochemistry – that, for example, the serotonin 2A receptor is creating structural changes in the brain. For a pharmaceutical company that wants to develop the next blockbuster antidepressant, the most economical, scalable option is to take a drug like psilocybin, where you know the molecular mechanism, and engineer out the trip. They think the trip is sort of epiphenomenal (incidental and not important), and if they can create the same structural plasticity changes in the brain, then people will get better. That’s classic pharmacological logic.

The drug versus the trip – that’s the argument in a nutshell. The answer is important. If it’s just about the drug, then we don’t have to change anything about how we design mental health therapeutics, right? It’s just molecular math and engineering. But if it turns out that it’s not the drug, it’s the trip, that changes the framing of what gets people better – you’d need to bring transformative, ecstatic, profound experience into mainstream mental health care. That’s very difficult to envision. It requires new models of care delivery that are not necessarily scalable. That has always been the challenge that psychedelics pose.

Is dreaming under anesthesia preferable to tripping on psychedelics? How do the experiences compare?

People have often compared classic psychedelics to dreaming, and there is some overlap, but it’s not the same. They are nonordinary, immersive experiences that check some of the same boxes, such as a different sense of space and time and a loss of metacognition (or thinking about thinking). We’ve measured the “psychedelicness” of anesthesia dreaming with the Mystical Experience Questionnaire in the lab – it rates at a pretty decent dose of psilocybin. But the dreams don’t tend to be bizarre; they’re not like hallucinations.

I’ll tell you what some patients with PTSD have told us: “I don’t want to be in a room for six hours tripping with all of these ghosts coming up to haunt me.” There is a lot of hope for psychedelics and also more than a little trepidation. It’s not for everyone.

A lot of the hesitation that people have is about the intensity and the difficulty of this type of experience. And it really requires guidance. Anesthesia dreaming is a very different proposition and, I think, might be more palatable. It’s shorter; it’s more controllable. The whole process takes about an hour.