Short naps and exercise improve sleep quality and mental health in the elderly. - TANAKA, HIDEKI; TAIRA, KAZUHIKO; ARAKAWA, MASASHI; URASAKI, CHISAE; YAMAMOTO, YUKARI; OKUMA, HIROMI; UEZU, EIKO; SUGITA, YOSHIRO; SHIRAKAWA, SHUICHIRO (Psychiatry & Clinical Neurosciences, 2002)