United States Navy and NASA researchers have each examined the impact of sleep in individuals living and working underwater but researchers with Clayton Sleep Institute (CSI) in St. Louis are hoping to gain new insight with a study in cooperation with Fabien Cousteau's Mission 31.
The study teams the sleep researchers with aquanauts to examine how factors such as low light exposure, ambient pressure, air gas mixtures, stress and isolation may impact sleep.
The study, "Sleep/Wake Monitoring with Actigraphy during a 31-Day Underwater Marine Expedition" is led by Joseph M. Ojile, MD, founder and CEO of CSI, and Christopher L. Drake, PhD, from the Henry Ford Hospital Sleep Disorders and Research Center.
Mission 31, an ambitious ocean research and education expedition led by Fabien Cousteau, grandson of famed ocean explorer Jacques-Yves Cousteau, began June 1 at Aquarius, a marine lab located 63 feet underwater off the coast of Key Largo, Fla., operated by Florida International University (FIU).
During their stay and for seven days after returning to the surface, Mission 31 aquanauts wore an Actiwatch 2, a wrist device that electronically maintains a record in one-to-two minute intervals of the user's activity, light exposure, and sleep pattern. The aquanauts also kept personal diaries of their sleep experiences.
"Research literature up to this point for sleep in individuals underwater has not shown much in the way of sleep disturbances. We think that's because the study duration hasn't been prolonged; only two weeks at most with just a hint of disturbance at the very end," said Drake. "Some of the aquanauts with Mission 31 – Fabien Cousteau included – have been underwater for 31 days, which takes us into new territory."
"We believe that sleep disturbances begin to occur after the two week mark and become prominent at the four week period," he said. "That's what we are focused on and concerned about."
Ojile said the data collected could potentially help to treat patients with sleep disorders.
"Data from extreme environments can often be used in normal circumstances," Ojile said. "We may learn something interesting about changes in the aquanauts' circadian rhythms, or the length of time it takes for their sleep to normalize after surfacing may be noteworthy. The exciting thing is that we don't know what the research will show. That's why we're doing this."
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