Sensory deprivation Tanks

I watched a video by Vice news about sensory deprivation tanks. These tanks are designed to you brain to experience as little outside sensory stimulus as possible. Apparently doing this helps your brain realize its own existence. It is good for meditation and relaxation. The video showed a guy experiencing 3 different “Float Tanks” in California and Colorado. The tanks are basically little pods that have about 8 inches of water and are completely dark. The tanks kind of vary in design but all have the same basic principal. The object is to stay in the tank for as long as you want, and meditate to experience your own thoughts and bodily sensations.  The guy in the video floated for 8 hours and 5 hours. He explained that he experience feelings of calmness and clarity. During the 8 hour float, his goal was to control his ADHD.