Floating nude in a dark Minnetonka salt tank – what could go wrong?

What is it? Floating in a dark, quiet, enclosed space. Researchers refer to it as flotation restricted environmental stimulation therapy (REST), or sensory isolation floating.

Why would you do it? Quieting the nervous system in gravity-free surroundings seems to allow the body to relax and recover from ailments, and the mind to focus. There are also benefits associated with the magnesium in the water. Plus, the NBA's Steph Curry loves it and credits it for making him great on-court.

The evidence is not just anecdotal. Scientists have studied the effects of floating on people who have problems ranging from PTSD to chronic back pain. They've also studied people who are well, considering flotation as a preventive health measure. The research shows positive effects: lower levels of cortisol and blood pressure, decreases in stress, anxiety and pain, and increases in mindfulness, optimism and sleep quality.

My take? The idea of being put in the type of float pod I'd seen decades ago (like a barrel with a closed lid) sounded panic-inducing rather than soothing. That changed when I found out about a new generation of tanks that look like big bathtubs. I headed to Minnetonka's Sanctuary Float Spa to check out their float operation.

The setup: Abby Sather, the manager, greeted me and showed me to a private locker room with a bench, clothes hooks, mirror and shower door. Behind the door was a shallow, wide tub, filled with 1,000 pounds of pharmaceutical-grade Epsom salt dissolved in water. That saline saturation makes you float.

She pointed out dials on the wall of the tub that controlled lights, music and an intercom, in case I needed to call for help. On the opposite wall was a metal handrail, and tucked behind that were two small foam pillows. "Your head will float, but your body will instinctively try to hold it up, and that can cause tension," she said, "So these are here if you need them." She tucked a towel behind the rail, too. "If you get salt in your eyes, it will sting. If you get it in your mouth, it will taste awful," she said. "This is to wipe off."

She asked me to shower before and after I soaked and informed me I'd be floating nude "since we like to keep impurities from fabrics from getting in the tank." While most people recline in the tank, she said I could also sit or stand if I needed to. She explained that she'd gradually dim the lights until the room was completely dark. When my hour was up, she'd raise the lights and turn up the music.

What's it like? I showered, put in the earplugs, and stepped into the tank. The water was body-temperature. I sank down, stretched out and ... floated. Slowly, the lights dimmed. I could hear only my breath, my heartbeat and a little splashing when I moved. I couldn't see my hand in front of my face.

I tried to meditate. I couldn't tell how much time had gone by when I noticed my toes were cold. I decided to flip onto my belly to warm them up, but it was a clumsy maneuver. I ended up getting water in my eyes. Sather was right. It stung. I reached for where I thought the towel was, but I felt only wall. Somehow, I'd pivoted 180 degrees, so my head was where my feet had been when I started. Once I got myself oriented, I felt my way along the wall back to the bar, wiped my eyes, and resettled myself.

I slowed my breath and focused my mind on the here and now by repeating: "Now I am breathing in ... now I am breathing out." I turned on soft, ambient music. Somewhere among the inhales and exhales, I fell fast asleep. I woke up to the lights slowly brightening and the music growing louder. My face was crusted with salt, and I had water lodged in one ear. My toes were still cold. But I felt calm and relaxed, like I'd slept for hours.

Who's it for? It's a low-risk spa service for anyone who wants to relax, manage stress, increase focus, even perform better athletically.

Who's it not for? If you panic at the thought of absolute darkness, isolation and small spaces, you might find this a tough sell.

Cost: A first-time float is half off; a full-price hour costs $90. Other companies offer similar services. Check for deals on Groupon.