Out of this world physiology

URBANA, ILLINOIS — In his five months on the space station Mir in 1997, Jerry Linenger endured a fire, a faulty oxygen generator, and a failed cooling system that leaked antifreeze fumes and temporarily converted the cabin climate to rain forest redux. But he still managed to monitor himself adequately enough to document a new risk of long-term manned space flight, a type of prolonged jetlag that could impair the performance of astronauts over long missions.

The study, reported in November/December Psychosomatic Medicine, is one of a number of recent studies on manned space flight that have raised serious concerns about how long humans can stay healthy in space. They also shed new light on various aspects of human physiology — in both normal and diseased states.

Diurnal rhythms in humans affect sleep-wake cycles, body temperature, alertness and the performance of a variety of tasks. These are controlled by external ...