In 1956 Sister Jean Ward of the Premature Unit of the Rochford General Hospital in Essex, England noted the benefit of phototherapy when she took infants outside because she assumed that fresh air had healing benefits. In areas exposed to outdoor light, she and other doctors noted that the yellow tint of jaundice began to disappear. The staff of the hospital also found that bilirubin levels decreased in vials of blood set in the sunlight. Cremer, a physician, and "Pediatric Registrar" at Rochford General Hospital, created the first phototherapy machine to explore the effects of artificial light on premature infants. Cremer co-authored the paper with Perryman, a biochemist, and Richards, chief technician of the biochemistry department of the hospital.
(Thanks to Juan Weiss for this reference and its interpretation.)