I have used binaural beats for years in brain machines and the products from the inventors The Monroe Institute (www.monroeinstitute.org). They put one into a deeply relaxing "body asleep, mind awake" state.

The latest variation is Holosync from Centerpointe. (www.centerpointe.com)
Among their claims: Increased DHEA and melatonin and decreased cortisol indicating stress reduction. Oddly enough, it made me agitated but my brain reacts oddly to things.