Hypnosis

Description: A practice that induces a state of intensely focused attention, so that the subconscious mind becomes more powerful.

Effectiveness: There's solid evidence that it can reduce pain and anxiety for minimally invasive procedures. It also works for chronic pain, severe burns, and disorders worsened by stress, such as irritable bowel syndrome and eczema. While it helps some people quit smoking, it's not effective for everyone—though it's still worth a try.