"Hot yoga" is the general term for yoga performed in a climate-controlled studio with the heat and humidity jacked up to tropical intensity. The original hot yoga, Bikram, cranks it up to 105 degrees Fahrenheit and throws in a bonus of 40 percent humidity so you really feel like you're in the south of India.
Other hot yoga studios may not be as extreme, but the theory is the same: doing yoga in high heat bestows wondrous health benefits that just don't happen at room temperature, or so it's claimed. Some people experience this as bliss, while others regard it as an 60 to 90 minutes (depending on the class) in a hell realm that's good for them.
What are the benefits of hot yoga? While there's not a huge amount of scientific research exploring the question, several studies have been made. The open question, though, is whether hot yoga does anything for you that regular yoga doesn't.
Better Sleep
Heat relaxes muscle and induces sleepiness, so it's not surprising that hot yoga could help improve sleep. Ninety-four percent of participants in a 2014 study in the International Journal of Clinical and Experimental Medicine reported a better quality of sleep when they did Bikram regularly for one year.
Throw Fat on the Fire
People doing hot yoga have been shown to experience weight loss. A 2014 study of 50 middle-aged, overweight women in the International Journal of Clinical and Experimental Medicine found that after one year of doing hot yoga on a regular basis, most experienced lower body fat and improved physiques. It helps that there's an extra metabolic advantage to exercising in a hot room: the body's elevated temperature boosts its energy consumption, causing it to use as much as 10 to 40 percent more energy.
Improved Blood Sugar
Hot yoga may improve blood sugar levels, particularly if you're carrying excess weight, according to a 2015 pilot study in the Journal of Bodywork and Movement Therapies. Glucose scores were significantly improved for older, obese participants receiving a glucose tolerance test before and after an 8-week Bikram intervention.
Increased Flexibility
Of course, any yoga done halfway right will increase your flexibility. But stretching when your muscles, tendons and ligaments are nice and warm provides an undeniable advantage, possibly allowing for deeper stretches. You don't have to be in 100-degree heat to get your muscles warmed up, but it's certainly one way to go.