 SKP-1041 is a new formulation of a marketed sleeping agent called zaleplon. Zaleplon is currently available as Sonata as well as several generic formulations. Sonata and its generics induce sleep soon after ingestion. SKP-1041, however, is a formulation that is designed to become active 2-3 hours after ingestion. It is intended for use in people who have no trouble falling to sleep but who often awaken in the middle of the night. This trial will determine the best dose to prevent those awakenings. 