Neuron
Volume 85, Issue 6, 18 March 2015, Pages 1193-1199
Journal home page for Neuron

Report
Melatonin Is Required for the Circadian Regulation of Sleep

https://doi.org/10.1016/j.neuron.2015.02.016Get rights and content
Under an Elsevier user license
open archive

Highlights

  • Zebrafish lacking melatonin have dramatically reduced sleep at night

  • Melatonin is required for circadian regulation of sleep

  • Melatonin is not required for normal circadian rhythms

  • Melatonin may promote sleep in part via adenosine signaling

Summary

Sleep is an evolutionarily conserved behavioral state whose regulation is poorly understood. A classical model posits that sleep is regulated by homeostatic and circadian mechanisms. Several factors have been implicated in mediating the homeostatic regulation of sleep, but molecules underlying the circadian mechanism are unknown. Here we use animals lacking melatonin due to mutation of arylalkylamine N-acetyltransferase 2 (aanat2) to show that melatonin is required for circadian regulation of sleep in zebrafish. Sleep is dramatically reduced at night in aanat2 mutants maintained in light/dark conditions, and the circadian regulation of sleep is abolished in free-running conditions. We find that melatonin promotes sleep downstream of the circadian clock as it is not required to initiate or maintain circadian rhythms. Additionally, we provide evidence that melatonin may induce sleep in part by promoting adenosine signaling, thus potentially linking circadian and homeostatic control of sleep.

Cited by (0)