RPamide neuropeptides NLP-22 and NLP-2 act through GnRH-like receptors to promote sleep and wakefulness in C. elegans.

Sleep and wakefulness are fundamental behavioral states of which the underlying molecular principles are becoming slowly elucidated. Transitions between these states require the coordination of multiple neurochemical and modulatory systems. In Caenorhabditis elegans sleep occurs during a larval transition stage called lethargus and is induced by somnogenic neuropeptides.

Interneurons Regulate Locomotion Quiescence via Cyclic Adenosine Monophosphate Signaling During Stress-Induced Sleep in .

Sleep is evolutionarily conserved, thus studying simple invertebrates such as can provide mechanistic insight into sleep with single cell resolution. A conserved pathway regulating sleep across phylogeny involves cyclic adenosine monophosphate (cAMP), a ubiquitous second messenger that functions in neurons by activating protein kinase A. sleep in response to cellular stress caused by environmental insults [stress-induced sleep (SIS)], a model for studying sleep during sickness.