Depending on who you ask, spending an hour floating naked in a soundproof, lightproof tank with only your own thoughts for company sounds either like a soothing respite from everyday life, or a nightmarish punishment devised by a uniquely devious and vengeful deity. Personally, I yearn for the void. So I signed up for a session in a float tank. These used to be called sensory deprivation tanks, but the term has fallen out of favor because your senses aren’t fully deprived; the terms of art are flotation therapy or flotation Rest (restricted environmental stimulation therapy). Isolation tanks were first developed in the 1950s by John C Lilly, a neuroscientist who used them to enhance his psychedelic experiences. They didn’t become commercially available until the 1970s but their popularity quickly grew. Since then, float tanks have drifted in and out of the zeitgeist. Proponents say they help alleviate stress and muscle pain, and induce a deeply relaxing meditative state. When interviewed by ESPN at a float spa in 2015, the NBA star Stephen Curry said: “It’s just me and my thoughts for an hour, playing Russian roulette of the mind.” But when I told friends about my upcoming appointment, some looked at me with wide, panicked eyes. “I don’t need to be alone with my thoughts,” one said. What are the benefits of float therapy? Although float therapy has been around for decades and the results of existing studies are promising, it is still not being widely researched. Dr Justin Feinstein, a clinical neuropsychologist and president and director of the Float Research Collective, a non-profit organization focused on getting float therapy approved as an accepted medical treatment, says floating is an effective way to counteract the relentless noise and distraction of modern life. According to Feinstein, studies have found that after a float, patients experience a significant decrease in stress and anxiety, and an improvement in mood, serenity and relaxation. He adds that these effects can last up to 48 hours. “In the patients that came in with a lot of stress and anxiety, there was this residue that seemed to last for about one to two days post-float,” he says. Feinstein says that his research suggests floating can be especially helpful for people with chronic stress and anxiety, and conditions like PTSD, generalized anxiety disorder and anorexia nervosa. What happens in your body when you float? “The first thing we notice is blood pressure,” says Feinstein. Within five to 10 minutes of starting a float, there is a precipitous drop in blood pressure. Part of this, he says, is probably due to reduced muscle tension. “[A float] is one of the few places on Earth where you can experience this almost zero-gravity feeling,” he says. This allows the smooth muscles around your veins and arteries to relax and contract, which allows blood vessels to expand, and blood to flow more freely. Breathing also slows significantly, by about one breath per minute. Slower, deeper breathing has been found to help reduce feelings of stress and anxiety. Then there are the mental effects. According to Feinstein, during a float, brainwaves “slow to a trickle”, even in floaters who are awake. In studies conducted by Feinstein and his colleagues, they observed that delta waves – “the slowest type of brainwave you could get, the type you typically would only see in a state of deep sleep” – became quite prominent during a float. “You typically don’t see that in any other conscious states,” he says. How does float therapy feel? I arrived at the float spa on a dreary, snowy day. After a brief wait in a sitting area dotted with Thich Nhat Hanh books and large pallets of Epsom salt, I was guided to a tasteful wood-paneled room dominated by what looked like an enormous, white acrylic egg lying on its side. I had expected the tank to be the size of a large bathtub, but I felt I could host an intimate dinner party in this colossus. The attendant politely informed me that I had 10 minutes to shower and shampoo while the tank filled, so as not to taint the vessel with dead skin cells, body oil or hair product. I was also encouraged to cover any open wounds with the petroleum jelly that had been provided, to protect them from the sting of the salt. All showered, and with petroleum jelly smeared onto a small scratch on my finger, I slid into the body temperature water and pulled the tank’s top half down behind me. This spa also offered float pools in soundproof rooms – an excellent option for those who struggle with claustrophobia, Feinstein says. Each pod or pool is saturated with enough Epsom salt for one to float at the surface, a concentration of roughly 35%. For the first five minutes, speakers played the soothing sounds of waves, and gentle neon lights thrummed from red to green to purple. Then, I was engulfed by silence and darkness. The first few moments were serene. I focused on the pleasant physical sensation of floating. The darkness was so complete that having my eyes open or closed made no difference. Then came the thoughts. I am a regular meditator. I like to think I am familiar with the inner workings of my own mind. I am usually able to notice my racing thoughts and rope them in before they take over. But in the float tank, robbed of any ambient distractions, my brain set off at full speed, like a wild horse that had slipped its lead. What if I fall climbing out of this thing like Miranda does in that one episode of And Just Like That? I thought. I can’t believe Che Diaz won’t be in the next season. I can’t believe I watch that show. I need new clothes. Am I doing this right? What was that sound? I should let my thoughts float away like clouds. How long has it been? Shoot, I forgot to send that email. Eventually, I wrestled back some control. I focused on the tingly awareness in my fingertips. I took deep breaths and felt the dried salt on my ribs. My thoughts slowed and I zoned out, neither asleep nor awake. Every so often I’d experience an acute pang of consciousness, consumed again by my inner monologue, but then it would quiet. After an hour that felt like either 15 minutes or two days, the lights inside the tank came on and speakers started playing the sound of waves to signal I was done. I rinsed off in the shower and pulled on my clothes. On the walk home, I felt serene but untethered, like my brain had floated off into the sky and hadn’t landed back in my skull yet. Did I enjoy the float? It’s hard to say. The unobstructed glimpse into my own mind had been both illuminating and troubling. Why did I think so much about Che Diaz? Is there anyone who should avoid float therapy? According to the Cleveland Clinic, float therapy is not for everyone. It’s best to avoid it if you have claustrophobia, skin conditions that might be exacerbated by the salt water, an infectious disease, a seizure disorder or are prone to ear infections. Most float companies also ask you not to float if you’ve recently had your hair colored, but that’s not a health issue – they just don’t want the hair dye to stain the pristine pods. How much did it cost? $89. Did it work? I felt both relaxed and unsettled. Would I do it again? Yes, if someone else was paying. Did it fix me? It highlighted how pointless most of my thoughts are, and that I really shouldn’t let them dictate my moods. Obviously that still happens, but now I remember that most of what happens in my head is nonsense. Overall rating: Three out of five heaping bags of Epsom salt.