There is a famous cognitive psychology experiment where people were put into neutrally lit tanks of warm water, isolated from all extraneous sensory stimuli, with air for breathing provided.
After being placed in such an environment of sensory deprivation people lose any sense of time, and fell asleep soon. After waking the experiment subjects started hallucinating - these were primarily pleasant visual hallucinations.
My idea is that prolonged sensory deprivation gradually evokes extrasensory abilities and all of our 5 senses can be sharpened through such procedures.