In the NSA group, log-transformed UA-MWC during LBPP decreased significantly compared to control (9.3 ± 0.6 versus 9.6 ± 0.5, respectively), whereas in the OSA group, log-transformed UA-MWC during LBPP increased significantly compared to control (9.6 ± 0.3 versus 9.5 ± 0.4, respectively). The change in UA-XSA in response to LBPP differed significantly between the 2 groups (p < 0.001). Note that data are plotted on a log scale. LBPP, lower body positive pressure; NSA, no sleep apnea; OSA, obstructive sleep apnea; UA-MWC, upper airway mucosal water content.