The primary objective of this experiment was to document the effects of long-duration space flight on sleep-wake activity patterns using a wrist-worn Actiwatch. Additional objectives were to measure the ambulatory light exposure of individual crewmembers and to evaluate the effects of space flight on crewmembers' subjective evaluation of the amount and quality of their sleep.
The information derived from this study will help to better understand the effects of space flight on sleep, as well as aid in the development of effective countermeasures for long-duration space flight. Moreover, a better understanding of the etiology of insomnia is relevant to the millions of people on Earth who suffer nightly from insomnia. Finally, the advancement of state-of-the-art technology for monitoring, diagnosing, and assessing treatment effectiveness is vital to the continued treatment of insomnia on Earth and in space.
The second BDC session was from L-11 to L-0. The Actiwatch was again worn continuously for the eleven days before launch, and paper sleep logs were again completed in the mornings. The two sessions were designed to document the differences in sleep quality and quantity of crewmembers in their regular routines and right before a launch. After the mission is over, additional BDC data was taken. The last session is from R+0 to R+7. The watches were worn continuously for the eight days upon landing back on Earth. The paper sleep logs were again completed in the mornings.
The crewmembers donned the Actiwatch as soon as possible (within 48-hours of docking to ISS) and wore the watch continuously (day and night) throughout the mission with the exception of extravehicular activities (EVA) and showers. The crewmembers accessed an electronic sleep log on a Station Support Computer. Sleep logs were completed within 15 minutes of awakening/getting out of bed seven consecutive days every three weeks for the duration of the mission. The data from the Actiwatch was downlinked at least once per month to the investigators at the Johnson Space Center (JSC). This downlinking activity required no crew time. After each data download, the Actiwatch was re-initialized and donned for continued data collection. Within one week of arrival of the next Expedition crew, the current crew replaced the Actiwatch lithium battery with a fresh one and performed a final data download.
Investigators collected data from astronauts on space shuttle missions and ISS missions with ground-based data from all astronauts. Crewmembers attempted and obtained significantly less sleep per night as estimated by actigraphy during space shuttle missions, 11 days before space flight, and about 3 months before space flight compared with the first week post-mission. Crewmembers on ISS missions obtained significantly less sleep during space flight, in the 11 days before space flight, and during the 2-week interval scheduled about 3 months before space flight compared with in the first week post-mission. 61 of 78 shuttle-mission crewmembers reported taking a dose of sleep-promoting drug on 500 of 963 nights while 12 of 16 ISS crewmembers reported using sleep-promoting drugs.
|Mission||Launch/Start Date||Landing/End Date||Duration|
|Expedition 14||09/18/2006||04/21/2007||215 days|
|Expedition 15||04/07/2007||10/21/2007||197 days|
|Expedition 16||10/10/2007||04/19/2008||192 days|
|Expedition 17||04/08/2008||10/23/2008||198 days|
|Expedition 18||10/12/2008||04/17/2009||187 days|
|Expedition 19||03/26/2009||10/11/2009||199 days|
|Expedition 20||05/27/2009||10/11/2009||137 days|
|Expedition 21||10/11/2009||12/01/2009||51 days|
|Expedition 22||11/30/2009||03/18/2010||109 days|
|Expedition 23||03/18/2010||06/01/2010||75 days|
|Expedition 24||06/01/2010||09/25/2010||117 days|
|Expedition 25||09/24/2010||11/25/2010||31 days|
|Expedition 26||11/26/2010||03/16/2011||111 days|