Williams during Sleep-Long Experiment in the US Lab during Expedition 15

ISS015-E-09449 (24 May 2007) --- Astronaut Sunita L. Williams, Expedition 15 flight engineer, enters data in a computer for the Sleep-Wake Actigraphy and Light Exposure During Spaceflight-Long (Sleep-Long) experiment in the Destiny laboratory of the International Space Station. Sleep-Long will examine the effects of spaceflight and ambient light exposure on the sleep-wake cycles of the crewmembers during long-duration stays on the station.