http://www.walkinbathtubpa.com/why-you-should-add-chromotherapy-to-your-walk-in-bathtub/

A walk in bathtub offers a wide range of features to create a safe and spa- like experience right in your home. One great feature available in our Pennsylvania walk in tubs is chromotherapy, which uses colored lights to balance the different energies inside the body to help reduce pain. Chromotherapy can enhance your bathing experience and benefit your health.