Fig. 1. Loss of righting reflex measurements after intraperitoneal administration of 30 mg/kg pentobarbital to wild-type (+/+), heterozygous (+/−), and mutant (−/−) mice. (  A ) Latency to the loss of righting reflex was shorter in the (−/−) mice (5.1 ± 0.5 min, n = 26) compared with the (+/−) and (+/+) mice (6.5 ± 0.4 min, n = 17, and 7.8 ± 0.9, n = 25, respectively;  P < 0.05). (  B ) Similarly, the duration of the loss of righting reflex (sleep time) was longer in the (−/−) mice compared with (+/−) and (+/+) littermates (18.1 ± 1.5  vs. 10.3 ± 1.3 and 10.8 ± 1.5 min, respectively;  P < 0.05).