It is argued that a quiescence state in nematodes, 'lethargus', presents many similarities with sleep as defined in mammals and flies. cGMP signalling is also identified as a new pathway involved in sleep control in both Caenorhabditis elegans and Drosophila. As lethargus is associated with the worm's larval molts, they suggest that sleep may have evolved to allow for developmental changes.
- David M. Raizen
- John E. Zimmerman
- Allan I. Pack
