Apparently, NASA is paying willing test subjects $17000 for spending 90 days lying in bed, (except for limited times for specific tests) with their body slightly tilted downward (head down, feet up). Every day, they will be awake for 16 hours and lights out (asleep) for 8 hours. Participants must be nonsmokers who are in good health with no history of cardiovascular, neurological, gastrointestinal, or musculoskeletal problems. Although after the test, that might no longer be the case.

http://www.nasa.gov/mission_pages/station/behindscenes/bed_rest_study.html
http://www.bedreststudy.com/Bedrest.aspx

-GordaMn