Fig. 5.

Arousal is delayed by 5-HT deficiency and active sleep. A: total time spent in quiet (QS) and active (AS) sleep while in room air as % of total time in the chamber for TPH2+/+ (WT) and TPH2−/−. B: no. of QS and AS episodes per hour for each genotype. *Significant difference between TPH2+/+ and TPH2−/− (P = 0.007). C: latencies to arousal from quiet sleep (QS, left) and active sleep (AS, right) of TPH2+/+ and TPH2−/− littermates in room air (n = 10 +/+, 8 −/−) and in response to CO₂ (n = 8 +/+, 7 −/−) or hypoxia (n = 8 +/+, 8 −/−). *Significant effect of genotype on arousal latencies in air and in response to increasing CO₂ (genotype × gas: P = 0.02). ^Significant effect of CO₂ or hypoxia on arousal latencies, compared with spontaneous arousal latencies in air (gas: P < 0.001). †Significant effect of AS on arousal latencies of TPH2−/− pups only (genotype × sleep state: P = 0.01). ††Significant effect of AS on arousal latencies of both genotypes in response to increasing CO₂ (state × gas: P = 0.001). D: ventilatory response [ΔV̇i/Δfractional concentration of inspired CO₂ ($\mathrm{F}{\mathrm{I}}_{\mathrm{C}{\mathrm{O}}_{\mathrm{2}}}$, left) or O₂ ($\mathrm{F}{\mathrm{I}}_{{\mathrm{O}}_{\mathrm{2}}}$, right)] of TPH2+/+ and TPH2−/− littermates.