Lethargus is a Caenorhabditis elegans sleep-like state

David M. Raizen, John E. Zimmerman, Matthew H. Maycock, Uyen D. Ta, Young Jai You, Meera V. Sundaram, Allan I. Pack

Research output: Contribution to journalArticlepeer-review

334 Scopus citations


There are fundamental similarities between sleep in mammals and quiescence in the arthropod Drosophila melanogaster, suggesting that sleep-like states are evolutionarily ancient. The nematode Caenorhabditis elegans also has a quiescent behavioural state during a period called lethargus, which occurs before each of the four moults. Like sleep, lethargus maintains a constant temporal relationship with the expression of the C. elegans Period homologue LIN-42 (ref. 5). Here we show that quiescence associated with lethargus has the additional sleep-like properties of reversibility, reduced responsiveness and homeostasis. We identify the cGMP-dependent protein kinase (PKG) gene egl-4 as a regulator of sleep-like behaviour, and show that egl-4 functions in sensory neurons to promote the C. elegans sleep-like state. Conserved effects on sleep-like behaviour of homologous genes in C. elegans and Drosophila suggest a common genetic regulation of sleep-like states in arthropods and nematodes. Our results indicate that C. elegans is a suitable model system for the study of sleep regulation. The association of this C. elegans sleep-like state with developmental changes that occur with larval moults suggests that sleep may have evolved to allow for developmental changes.

Original languageEnglish (US)
Pages (from-to)569-572
Number of pages4
Issue number7178
StatePublished - Jan 31 2008

ASJC Scopus subject areas

  • General


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