The Sleep-Wake Immune Functions (SWIF) experiment is a two-year study of astronauts and cosmonauts aboard the Mir space station to help further understand the link between our unconcious sleep/wake schedules and immunity.
Aboard the Russian space station, six subjects will keep diaries, give blood samples and wear sleep monitoring devices in order to understand how changes in the space environment affect the sleep/wake schedule, and in turn, resistence to disease. Previous space travellers have made numerous reports of weakened immunity during their missions, implying a unusually high vulnerability in space.
Many factors are believed to affect the sleep/wake schedule in space. Some are environmental, such as magnetic fields, the absence of earth's gravity or trying to cope with 17 sunrises and sunsets every day while keeping the body's inner clock on a regular day/night schedule.
Other less exotic variables include noise and fluctuating temperatures and psychological disturbances, such as anxiety and excitement, which are all believed to cause interference to the sleep/wake schedule.
In all cases, the body's inner clock is affected and often misses important cues. This can result in fatigue, poor disposition and impaired performance.
Dr. Harvey Moldofsky, of the University of Toronto, SWIF's principal investigator, says that these disturbances to the sleep/wake schedule also cause our natural defence system to weaken, leaving us more susceptible to disease. The SWIF study aboard the Mir space station will help isolate the "earthly" variables and discover the extent to which this link between sleep and immunity exists.
Dr. Moldofsky's study is one of three being performed by Pittsburgh University, Harvard University and Toronto University. The joint effort is the most ambitious to date with regard to sleep, body rhythms and the immune system.
Results from SWIF will have important clinical implications for related psychiatric and medical disorders, including stress and depression, which along with chronic fatigue syndrome have been recently linked with altered immune functions.
Together these studies will also provide a better knowledge of the capabilities of humans to adapt to prolonged stays in space for scientific work aboard Mir and the International Space Station.