Like the Tibetan monks, Indian Yogis seem to have an unusual talent for manipulating their physiological processes while in deep meditation. After hearing stories of yogis spending 28 days underground and surviving, in 1936, a French cardiologist named Therese Brosse traveled to India to see if the yogis truly did have such talents. In her experiments, the yogis reportedly slowed their heart down so slow that it was only detectable via an EKG machine.
In the 1950s Brosse’s study was expanded by another group of researchers who traveled through India with an eight-channel electro-encephalograph and various other instruments, which they used to monitor the yogis’ brain activity, respirations, skin temperature, blood-volume changes, and skin conductance. Two of their test subjects were placed in air-tight sealed boxes, on two separate occasions, and were monitored for 8 to 10 hours. During that time the Yogis showed biological characteristics similar to sleep and were able to slow down their heart rate and respiration to low enough levels that oxygen and carbon dioxide quantities inside the box remained virtually in the same proportions as found in air at sea level. Thus, it was shown that by slowing down their bodily processes and not panicking (as most would do) the Yogis could survive a live-burial for far longer than the average person, possibly even weeks longer.