Sleep is an essential behavior exhibited by nearly all animals, and disruption of this process is associated with an array of physiological and behavioral deficits. Sleep is defined by changes in sensory gating that reduce sensory input to the brain, but little is known about the neural basis for interactions between sleep and sensory processing. Blind Mexican cavefish comprise an extant surface dwelling form and 29 cave morphs that have independently evolved increased numbers of mechanoreceptive lateral line neuromasts and convergent evolution of sleep loss. Ablation of the lateral line enhanced sleep in the Pachón cavefish population, suggesting that heightened sensory input underlies evolutionarily derived sleep loss. Targeted lateral line ablation and behavioral analysis localized the wake-promoting neuromasts in Pachón cavefish to superficial neuromasts of the trunk and cranial regions. Strikingly, lateral line ablation did not affect sleep in four other cavefish populations, suggesting that distinct neural mechanisms regulate the evolution of sleep loss in independently derived cavefish populations. Cavefish are subject to seasonal changes in food availability, raising the possibility that sensory modulation of sleep is influenced by metabolic state. We found that starvation promotes sleep in Pachón cavefish, and is not enhanced by lateral line ablation, suggesting that functional interactions occur between sensory and metabolic regulation of sleep. Taken together, these findings support a model where sensory processing contributes to evolutionarily derived changes in sleep that are modulated in accordance with food availability.
The authors declare no competing or financial interests.
Experiments were designed by J.J., B.A.S., M.Y. and A.C.K. Data collection was performed by J.J., B.G.R., I.O. and M.Y. Data analysis was performed by J.J., B.A.S., M.Y., I.O. and P.M. The paper was written by J.J., B.A.S., M.Y. and A.C.K.
This work was supported by a National Science Foundation IOS 125762 award to A.C.K. and an undergraduate Evo-Devo-Eco Network (EDEN) award to B.G.R.
Supplementary information available online at http://jeb.biologists.org/lookup/doi/10.1242/jeb.145128.supplemental
- Received June 27, 2016.
- Accepted October 23, 2016.
- © 2017. Published by The Company of Biologists Ltd