Fig. 9.

Mean (SE) SpO₂ in NB (a) and HV (b) series during A1–A5. The grey boxes indicate apnea time. Negative time values before apnea time indicate breathing just before apneas. Positive values after apnea time indicate recovery time directly after apneas and partly overlap with pre-apnea values of the subsequent apnea. The gap in the middle of apnea time has variable duration, as apnea duration was different between participants. *p < 0.05, **p < 0.01, ***p < 0.001 indicates significance compared with A1 in the same condition; ^†††p < 0.001 indicates significance compared with HV (n = 18)