Complex sentence: Cranial Electrotherapy Stimulation (CES) medicinal practice was originally developed in the Soviet Union in 1949, its primary focus being the treatment of sleep disorders--hence, its original designation as "electrosleep".
Split into simpler sentences: Cranial Electrotherapy Stimulation (CES) medicinal practice was originally developed in the Soviet Union in 1949. Its primary focus being the treatment of sleep disorders--hence, its original designation as "electrosleep".