The Hypocretin/Orexin signaling pathway suppresses sleep and promotes arousal, whereas the loss of Hypocretin/Orexin results in narcolepsy, including the involuntary loss of muscle tone (cataplexy).¹ Here, we show that the South Asian fish species Chromobotia macracanthus exhibits a sleep-like state during which individuals stop swimming and rest on their side. Strikingly, we discovered that the Hypocretin/Orexin system is pseudogenized in C. macracanthus, but in contrast to Hypocretin-deficient mammals, C. macracanthus does not suffer from sudden behavioral arrests. Similarly, zebrafish mutations in hypocretin/orexin show no evident signs of cataplectic-like episodes. Notably, four additional species in the Botiidae family also lack a functional Hypocretin/Orexin system. These findings identify the first vertebrate family that does not rely on a functional Hypocretin/Orexin system for the regulation of sleep and arousal.

下丘脑分泌素/食欲素信号通路抑制睡眠并促进觉醒，而下丘脑分泌素/食欲素的缺失会导致发作性睡病，包括肌张力不自主丧失（猝倒症）。¹在这里，我们展示了南亚鱼类Chromobotia macracanthus表现出一种类似睡眠的状态，在此状态下个体停止游泳并侧卧休息。引人注目的是，我们发现C. macracanthus中的下丘脑分泌素/食欲素系统是假生成的，但与缺乏下丘脑分泌素的哺乳动物相比，C. macracanthus不会出现突然的行为停滞。同样，斑马鱼下丘脑分泌素/食欲素突变也没有表现出明显的猝倒样发作迹象。值得注意的是，Botiidae 家族中的另外四个物种也缺乏功能性的下丘脑分泌素/食欲素系统。这些发现确定了第一个不依赖功能性下丘脑分泌素/食欲素系统来调节睡眠和觉醒的脊椎动物家族。