FIG. 2.

Mean nocturnal S_pO₂ over the study time course. In each panel, the mean nocturnal S_pO₂ versus study night before, during, and after high altitude exposure for the entire group (all subjects, left panel) and for subgroups of marked (middle panel) and mild desaturators (right panel), based on median split of the mean nocturnal S_pO₂ values during the first two nights at HA. Night 8 was not considered for the analysis because subjects slept at a higher altitude during that night (from 2,750 to 2,970 m). *, Mean nocturnal S_pO₂ sea level versus high altitude; δ, mean nocturnal S_pO₂, first versus last night at HA. See results section, “Effect of altitude and acclimatization on nocturnal oxyhemoglobin saturation profile.” S_pO₂, oxyhemoglobin saturation.