Sleep disordered breathing and obesity: Independent effec...(lth risks according to another research ...),Health

"Overnight fluid displacement from legs, related to prolonged sitting, may play a previously unrecognized role in the pathogenesis of OSA," wrote principle investigator, T. Douglass Bradley, M.D., professor of medicine and director of the Centre for Sleep Medicine and Circadian Biology at the University of Toronto,

The research also found that the volume of fluid shift was directly linked to the hours in a day that the subject reported sitting or standing and was independent of the excess weight that often accompanies sedentary lifestyles.

"In more recent years, the introduction of modern technologies into the workplace has greatly reduced the need for physical activity and increased the number of jobs requiring prolonged sitting, during which absence of the contraction of calf muscles leads to dependent fluid accumulation in the legs that is proportional to the time spent in that position," explained Dr. Bradley. "When assuming the recumbent position at bedtime, the fluid retained in the legs during the day in redistributed to the upper body. It is therefore plausible that some of the displaced fluid might reach the neck and predispose to upper airway constriction."

To determine whether that, in fact, was the case, the researchers recruited 23 nonobese subjects who were being evaluated for suspected OSA and performed standard sleep studies that assessed each subject for sleep stages and number of arousals, as well as oxygen saturation of the blood. The circumferences of their calves and necks were also measured at bedtime and upon awakening, before they got up.

Indeed, they found that the only significant correlate factor with respect to severity of OSA was the overnight change of fluid volume in the leg, which explained 67% of the variance in OSA severity. The change
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