A sleep state during C. elegans development

▶ Caenorhabditis elegans sleep occurs during lethargus, a larval stage transition period. ▶ Sensory gating during C. elegans sleep occurs in sensory neurons. ▶ C. elegans sleep is regulated by both neural and non-neural mechanisms. ▶ Genetic regulation of C. elegans sleep shares features with that of other species. ▶ Future work will identify cellular interactions regulating C. elegans sleep.

Caenorhabditis elegans is the simplest animal shown to sleep. It sleeps during lethargus, a larval transition stage. Behavior during lethargus has the sleep properties of a specific quiescent posture and elevated arousal threshold that are reversible to strong stimulation and of increased sleep drive following sleep deprivation. Genetic similarities between sleep regulation during C. elegans lethargus and sleep regulation in other animals point to a sleep state that was an evolutionarily ancestor to sleep both in C. elegans and other animals. Recent publications have shed light on key questions in sleep biology: First, How is sleep regulated? Second, How is sensory information gated during sleep? Third, How is sleep homeostasis mediated? Fourth, What is the core function of sleep?