Andries put on music—flutes and vocals without intelligible words or a beat. As the pill turned to goo in my mouth, I sank into a fluid warmth and felt as if I'd become a jellyfish-like blob. Behind my eyelids a vast space seemed to open up. Michael had called it the "planetarium," and it did feel like gazing up at an immense night sky. The usual stream of thoughts became more distant as I contemplated this inner universe.

After a second pill, Andries asked if there was anything I would like to talk about. Here's what poured out: my mother. It had been nearly 10 years since she died at a relatively young 63 from mesothelioma, a cancer almost entirely linked with asbestos exposure. She refused treatment—removal of one lung and half her diaphragm, and chemotherapy—which was unlikely to help in the long run anyway. I cared for her as she deteriorated over six months. Her pain had been difficult to control, and at one point toward the end, she awoke from her delirium and whispered, "Help me." I understood that she was asking my sister and me to help her die. Distraught, we said we couldn't. She died a few days later, in the morning. I was sleeping next to her, holding her hand, and was awoken by her final, rattling breath.

Nearly a decade later, I was still haunted by the experience. I was broke when she fell ill, as was she. Being poor is always rough, but it seems particularly undignified when you're terminally ill. I'd always planned for her to eventually live with me, to give her the space to relax and enjoy life when I had a house and a family—which I now had.

I wept as I told Wolfson and Andries this. "She was supposed to be here," I said. Wolfson told me to "stop twisting the knife" so I could fully engage my memories of her. I'd done everything a good son could be expected to do.

"There wasn't enough time," Andries said. "There just wasn't enough time."

As they consoled me, I saw my mother as a young woman in my mind's eye, her dark hair in two long braids, and also the graying, handsome woman she aged into before she got sick. I embraced these phantoms, wrote "I love you" on scraps of paper in my mind, and tossed them into the space of the planetarium, hoping they would find her, but also knowing they probably wouldn't because she was, I still understood, gone.

After the session I was emotionally raw, crying randomly, and unsure of what to do with an overwhelming feeling of tenderness. All that faded in a few days, but what didn't disappear was this: a monster headache.

Some doctors use ketamine to treat migraines, but in my case the drug triggered a headache that lasted, on and off, for nearly a month. Wolfson said he'd never seen anything like it in more than 100 patients treated, and he prescribed a migraine medication for me. Wary of more side effects, I ultimately declined to take it.

The headache made the treatment untenable for me, even if I could afford the $1,000 I paid for the session on a regular basis. But the experience was illuminating. Ketamine seemed to pry open the black box of the mind, remaking it as a universe filled with discrete memories and emotions that you could revisit and relive. And as Wolfson had said, it imparted an unusual serenity. In daily life, when grief threatened to emerge, I tended to cringe. But on ketamine, I watched calmly as sorrow welled up and subsumed my body like warm water filling a tub. And it was OK.

As I thought about my experience, I kept returning to something Mason Turner of Kaiser Permanente, one of the authors on the APA recommendations, had said. Before Kaiser Permanente started its ketamine program, Turner's team had consulted with an extensive range of researchers and clinicians, including Wolfson.

Turner told me that the process had opened him to the possibility that, far from being unethical and dangerous, some of what was happening in practices like Wolfson's might represent innovation to be learned from and emulated.

When I asked for his takeaway on ketamine, he described it as the "most exciting treatment to come to the fore" during his career as a psychiatrist, and said depressed patients should have hope. But he had a more pointed message for scientists. The field was currently failing patients with treatment-resistant depression, he said. It needed all the help it could get. Scientists should "keep an open mind" and not dismiss, out of hand, knowledge accumulated at the grassroots level.

Usually, basic science filters down, he said. But in this case, useful techniques might filter up as well.