Effect of trazodone in a single dose before bedtime for sleep disorders accompanied by a depressive state: Dose-finding study with no concomitant use of hypnotic agent - Mashiko,H.; Niwa,S.-I.; Kumashiro,H.; Kaneko,Y.; Suzuki,S.; Numata,Y.; Horikoshi,R.; Watanabe,Y. (Psychiat Clin Neurosci, 1999)