Suzanne Nooij defended her doctoral dissertation in May 20, 2008, at Delft University of Technology, The Netherlands, alongside her PhD supervisor, Wubbo Eckels — the first Dutchman in space as a space shuttle passenger (1986). Nooij's dissertation topic was Space Adaptation Syndrome (SAS). SAS is experienced by up to 80% of all astronauts and usually lasts for not more than the first three days of space flight. Nooij's premise is that SAS occurs when humans experience the onset or conclusion of centrifuge-like motion (rotation) and when they adapt to different gravitational forces. She determined that SAS and rotational nausea are initiated by the same mechanism within the inner ear and are essentially attributable to asymmetric otolith and semicircular canal stimulation. In normal situations on Earth, otoliths sense linear motion, semicircular canals sense rotational information. Nooij's findings are consistent with the National Space Biomedical Research Institute (NSBRI) description (2007). NSBRI stated Apollo, Shuttle, Mir, and International Space Station crews reported motion sickness, in-flight disorientation, landing vertigo, vertigo, nausea and related physiologic disturbances which were attributed to adaptation to altered gravitational environments. Other factors that may impact SAS include reduced blood pressure (orthostatic hypotension) and conflicting sensory information delivered to the CNS from muscles, nerves, visual input, and the inner ear.
For More Information, References and Recommendations:
http://www.theregister.co.uk/2008/05/22/dutch_space_sickness_research/
http://www.nsbri.org/Research/StrategicPlans/Sensorimotor.pdf
http://www.nasa.gov/mission_pages/station/science/experiments/MOP.html
http://science.nasa.gov/headlines/y2002/25mar_dizzy.htm
http://www.mcgill.ca/reporter/37/06/cullen/