Skip to page content Mission Information


Assessment of Circadian Shifting in Astronauts by Bright Light (DSO 484)
Principal Investigator
Research Area:
Species Studied
Scientific Name: Homo sapiens Species: Human

In order to have 24-hour operations during space flight, astronauts must shift their work schedules. However, people who do shift work exhibit drowsiness, fatigue, sleep disturbances, and impaired performance and mood. To optimize performance during space flight it would be desirable for some astronauts to shift their circadian rhythms before launch. Circadian rhythms can be shifted by gradual changes in the sleep schedule or by periodic exposures to bright light. Cycles of body temperature, cortisol, and melatonin are markers of circadian rhythms. There were three variations to this study, which were fairly similar. Part A occurred on STS-46, STS-47, and STS-50. Part B occurred on STS-46, STS-47, STS-50, STS-65, STS-66, and STS-67. Part C occurred on STS-85. The general objectives across all of these missions were to test whether treating astronauts with sleep shifting and timed bright light over a 7-day preflight period could produce a nine- to twelve-hour phase shift in their circadian rhythms.

++ -- View more

Charles JB, Fritsch-Yelle JM, Whitson PA, Wood ML, Brown TE, Fortner GW. Cardiovascular deconditioning. In: Sawin CF, Taylor GR, Smith WL, editors. Extended Duration Orbiter Medical Project final report 1989-1995. Houston: NASA Johnson Space Center, 1999.

Whitson PA, Putcha L, Chen YM, Baker E. Melatonin and cortisol assessment of circadian shifts in astronauts before flight. Journal of Pineal Research . 1995 April; 18(3):141-7.[]

Circadian rhythm

Data Information
Data Availability
Archive is complete. Some data sets are online.
Data Sets + View data

Some data sets are not publicly available but can be requested.
Data Sets+ Request data

Cortisol, saliva
Cortisol, urine
++ -- View more

Mission/Study Information
Mission Launch/Start Date Landing/End Date Duration
STS-46 07/31/1992 08/08/1992 8 days
STS-47 09/12/1992 09/19/1992 7 days
STS-50 06/25/1992 07/09/1992 14 days
STS-65 07/08/1994 07/23/1994 15 days
STS-66 11/03/1994 11/14/1994 11 days
STS-67 03/02/1995 03/18/1995 17 days
STS-85 08/07/1997 08/19/1997 12 days

Additional Information
Managing NASA Center
Johnson Space Center (JSC)
Responsible NASA Representative
Johnson Space Center LSDA Office
Project Manager: Pamela A. Bieri
Institutional Support
National Aeronautics and Space Administration (NASA)
Hardware Items