In June, 1990, a workshop was put together at NASA/Johnson Space Cente
r to address difficulties the astronauts were having in adjusting thei
r wake and sleep schedule, both immediately before and during Space Sh
uttle missions. The workshop members, prominent investigators in human
circadian research, developed a number of strategies by which astrona
uts could tackle the problem of circadian adaptation within the demand
ing timetable of a Space Shuttle mission. The strategies included both
abrupt and gradual methods, and some approaches used artificial ''ver
y bright lights'' to reset the physiologic circadian pacemaker. The st
rategies have since been operationally implemented on Space Shuttle fl
ights, with good success. This is a report of the problems addressed b
y the workshop and its recommendations.