Cousins did research on the biochemistry of human emotions, which he long believed were the key to human beings' success in fighting illness. It was a belief he maintained even as he battled in 1964 a sudden-onset case of a crippling connective tissue disease, which was also referred to as a collagen disease. Experts at Dr. Rusk's rehabilitation clinic confirmed this diagnosis and added a diagnosis of ankylosing spondylitis. Told that he had one chance in 500 of recovery, Cousins developed his own recovery program. He took massive intravenous doses of Vitamin C and had self-induced bouts of laughter brought on by films of the television show "Candid Camera", and by various comic films. His positive attitude was not new to him, however. He had always been an optimist, known for his kindness to others, and his robust love of life itself. "I made the joyous discovery that ten minutes of genuine belly laughter had an anesthetic effect and would give me at least two hours of pain-free sleep," he reported. "When the pain-killing effect of the laughter wore off, we would switch on the motion picture projector again and not infrequently, it would lead to another pain-free interval." His struggle with that illness and his discovery of "laugh therapy" is detailed in his 1979 book "Anatomy of an Illness as Perceived by the Patient".