Delta brainwaves are the slowest of all the brainwaves. They are low frequency and deeply penetrating, like the slow beat of a drum. They are generated within the brain or through an MP3 like this to create the deepest meditation experience and dreamless sleep. Delta waves can suspend our external awareness and are the source of true empathy.

What is a delta wave? A delta wave is a high-amplitude brain wave with a frequency of oscillation between 0.5 and 4 hertz. Deep healing and regeneration are stimulated in this deep relaxation state, and that is why deep restorative sleep is so essential to the bodies healing process The more rest you are able to get, the stronger your immune system will be. 

With the delta brainwave state, health improves on all levels - including an extra immunity to sickness. Lack of sleep  ...