August 9, 2014
Sleep Deprivation “Pervasive” Problem In Astronauts Before, During Missions
redOrbit Staff & Wire Reports - Your Universe Online
Astronauts tend to suffer from a significant amount of sleep deficiency in the weeks leading up to liftoff and throughout the duration of their missions, the authors of a 10-year research project being hailed as the largest-ever analysis of sleep habits before and during space flight report in Friday’s edition of The Lancet Neurology.
As part of the study, experts from the Brigham and Women's Hospital (BWH) Division of Sleep and Circadian Disorders, the Harvard Medical School Division of Sleep Medicine, and the University of Colorado Sleep and Chronobiology Laboratory used data from 85 astronauts, 64 of whom had participated in a combined 80 space shuttle missions and 21 of whom had taken part in International Space Station (ISS) missions.
They recorded more than 4,000 nights worth of sleep on Earth and an additional 4,200 nights of slumber in space, using both objective and subjective evaluations of sleep quality. The astronauts wore a device known as an actigraph on their wrists, which tracks sleep and wake cycles, and also kept a daily diary recording their alertness levels and their own take on how well they had slept the previous evening.
While NASA, which helped fund the research, schedules 8.5 hours’ worth of sleep per night for crew members during spaceflight, the mean duration of sleep was actually less than six hours (5.96) on shuttle missions and only slightly more (6.09) on ISS missions. Only 12 percent of sleep episodes on shuttle missions and 24 percent on ISS missions lasted at least seven hours, compared to 42 percent and 50 percent respectively during post-flight nights.
The results also suggested the problems begin before the astronauts first leave the Earth’s atmosphere, as those polled averaged less than 6.5 hours of sleep per night during training (recorded roughly 12 weeks prior to spaceflight) – approximately 30 minutes per night less than the average American adult, according to the study authors.
“In ground-based studies, we know that sleeping less than six hours is associated with performance detriments,” lead author Dr. Laura K. Barger, an associate physiologist in the BWH Division of Sleep and Circadian Disorders, told Kim Painter of USA Today.
“Sleep deficiency is pervasive among crew members,” she added in a recent statement. “It’s clear that more effective measures are needed to promote adequate sleep in crew members, both during training and space flight, as sleep deficiency has been associated with performance decrements in numerous laboratory and field-based studies.”
According to AFP reporter Richard Ingham, the study also found that three-fourths of astronauts turned to sleep aids such as zolpidem (sold under the brand names Stilnox and Ambien) and zaleplon (sold under the brand names Sonata and Andante) in order to get some extra shut-eye while in space. In fact, medications were used on more than half of the nights, and in four out of 13 shuttle missions, all of the crew members took sleeping pills on the same night six percent of the time.
“The ability for a crew member to optimally perform if awakened from sleep by an emergency alarm may be jeopardized by the use of sleep-promoting pharmaceuticals,” said Barger. “Routine use of such medications by crew members operating spacecraft are of particular concern, given the US Federal Drug Administration (FDA) warning that patients using sleeping pills should be cautioned against engaging in hazardous occupations requiring complete mental alertness or motor coordination.”
That FDA warning, she noted, includes “potential impairment of performance of such activities that may occur the day following ingestion of sedative/hypnotics. This consideration is especially important because all crew members on a given mission may be under the influence of a sleep promoting medication at the same time.”
Senior author Dr. Charles Czeisler, chief of the BWH Division of Sleep and Circadian Disorders, added that future space missions “will require development of more effective countermeasures to promote sleep during spaceflight in order to optimize human performance. These measures may include scheduling modifications, strategically timed exposure to specific wavelengths of light, and behavioral strategies to ensure adequate sleep, which is essential for maintaining health, performance and safety.”
> NASA Interactive: How Astronauts are Affected by Space Exploration