The sleep-wake cycles of 4 developmentally delayed individuals with longstanding severe sleep disturbances were regulated using a faded bedtime procedure with response cost. Bedtimes were systematically delayed for each individual, thus increasing the probability of short latency to sleep onset. The response cost component, consisting of removing the individual from bed for 1 hour, was implemented when an individual did not experience short latency to sleep onset. A fading procedure was then applied successfully to advance the bedtimes and to gradually increase durations of sleep. Specifically, all 4 individuals had decreased amounts of nighttime sleep that increased following treatment. Two of the 4 individuals showed excessive daytime sleep that decreased following treatment. Three of the 4 individuals experienced decreases in night wakings following treatment. Both environmental and biological manipulations of the sleep-wake cycle are hypothesized as mechanisms of treatment. The relative advantages of this procedure over other procedures for the treatment of pediatric sleep disorders are discussed, as are directions for future research.