Crew off-duty day. Underway: Week 11 of Increment 16.
Peggy and Dan began the day with the daily reading of SLEEP (Sleep-Wake Actigraphy & Light Exposure during Spaceflight) experiment data accumulated during the night, for logging and filling in questionnaire entries in the experiment 's session file on the HRF-1 laptop for downlink. (To monitor the crewmembers ' sleep/wake patterns and light exposure, Dan and Peggy wear a special Actiwatch device which measures the light levels encountered by him as well as his patterns of sleep and activity throughout the Expedition. The log entries are done within 15 minutes of final awakening for seven consecutive days, as part of the crew 's discretionary 'job jar' task list.) Additional Details: ISS On-Orbit Status 12/31/07.