The proposed pilot study provides an opportunity to test the feasibility of a protocol to use with astronauts and other NASA personnel (e.g., flight surgeons, flight directors, and flight controllers) to assess potential carry over effects from sleep medications used during spaceflight operations (including overseas training periods), and following an abrupt awakening from sleep. This information is critically needed to establish optimal and individually tailored usage of sleep medications by key personnel relative to operational demands. The proposed protocol is a feasibility study that will determine the percentage change in sleep inertia from using a medication compared to normal sleep inertia. Subject participants will each choose a hypnotic as their preferred sleep aid; once an appropriate medication is identified, each subject volunteer, in a controlled setting in the Crew Quarters Facility at Johnson Space Center (JSC), will undergo several awakenings during two nights of sleep (one night with the medication, another night with a placebo). Cognitive performance, using a set of three measures, will be evaluated at each awakening. This process will occur under the direction of the study Principal Investigator, a NASA Flight Surgeon.