FIGURE 1.

Individual and grouped data showing the age‐related differences between Tph2 ^−/− and Tph2 ^+/+ mice on maximal inspiratory flow (V _Imax), minute ventilation (V _E), tidal volume (V _T), respiratory rate (RR), and oxygen saturation (SpO₂) during non‐flow limited breathing in non‐rapid eye movement (NREM) (A) and rapid eye movement sleep (B). Younger—Tph2 ^+/+ (n = 5), Tph2 ^−/− (n = 5); Older—Tph2 ^+/+ (n = 6), Tph2 ^−/− (n = 9). Tph, tryptophan hydroxylase. *p < 0.05, **p < 0.01—effect of genotype using two‐way ANOVA. #p < 0.05 Tukey's post hoc test in comparison with older Tph2 ^+/+mice