Different lighting intensities and wavelengths are being implemented and studied further to entrain the circadian cycle of astronauts and to shift the sleep-wake schedules of crews in preparation for critical events, such as dockings between spacecraft. Special shielding on spacecraft, including the International Space Station, helps to protect against the harmful effects of space radiation. In addition, missions are adapted when radiation exposure is particularly high, such as during solar flares.
Medications have proven effective in treating space motion sickness and orthostatic hypotension, and some are potentially useful in reducing bone loss. Researchers continue to look for new ways to counteract the physical changes associated with long-term space flight whether through diet, exercise, medication or a combination of strategies.
Answer originally published October 6, 2003.