Now here is an interesting article. The Department of Homeland Security is examining an existing biofeedback technology to help with sleep. They are investigating the use of brain music therapy which has been in use since the early 1990s to treat medication conditions such as insomnia. Apparently brain waves are recorded and run through algorithms that analyze the waves and translate them into a music composition. According to the company Human Bionics, which sells this technology, these musical compositions are effective and scientifically proven treatments for stress, insomnia, anxiety, and depression. The technology has also been "found to increase productivity and concentration, and help reduce headaches."
I've not done the background research to see if these claims are reasonably true. The sample clip, however, makes for pretty music (though a bit repetitive).