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The Evolutionary Construction of Sleep


Nath, Ravi David (2018) The Evolutionary Construction of Sleep. Dissertation (Ph.D.), California Institute of Technology. doi:10.7907/JPDW-JW81.


To understand the biological basis of sleep we need to understand its neuronal and genetic regulation. In this thesis, I explore how individual behaviors serve as building blocks to construct the sleep state where a block is defined as a set of measurable behaviors. These behavioral blocks are shaped by evolutionary forces. From one animal to the next, blocks may remain or change. If a block remains across all the sleep states in the metazoan lineage then it must have an important and conserved role in sleep regulation. For example, reduced locomotion is a behavior that is often observed during sleep. There are two possible explanations for the changing of a block: either the block was vestigial or the block was easily replaceable with another block that fulfills the same function. Consider sleep duration: some animals may require five hours of sleep, while others only require one hour. The changing of a block is one way that the sleep state could evolve. Blocks may also be added during the evolution of the sleep state, increasing the dimensions and number of tasks that are accomplished during sleep. Here, I discuss the origin of sleep, as well as its conserved neuronal and genetic regulation. I report the following: the discovery of sleep in jellyfish which are among the first animals to evolve neurons and the identification of novel sleep regulators in the roundworm Nematode Caenorhabiditis elegans (C. elegans). The sleep regulators discovered in C. elegans may have conserved functions in vertebrates. These studies show that some sleep behaviors and various sleep molecules change or remain homologous across metazoans. The studies are united by our simple block hypothesis of sleep construction.

Item Type:Thesis (Dissertation (Ph.D.))
Subject Keywords:Sleep, C. elegans, Jellyfish, Behavior, Evolution
Degree Grantor:California Institute of Technology
Division:Biology and Biological Engineering
Major Option:Biology
Thesis Availability:Public (worldwide access)
Research Advisor(s):
  • Sternberg, Paul W.
Thesis Committee:
  • Prober, David A. (chair)
  • Gradinaru, Viviana
  • Anderson, David J.
  • Sternberg, Paul W.
Defense Date:4 May 2018
Non-Caltech Author Email:ravi37 (AT)
Funding AgencyGrant Number
Record Number:CaltechTHESIS:05272018-025533397
Persistent URL:
Related URLs:
URLURL TypeDescription to published version of Chapter 2. to published version of Chapter 3.
Nath, Ravi David0000-0003-0905-2707
Default Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:10948
Deposited By: Ravi Nath
Deposited On:01 Jun 2018 19:00
Last Modified:04 Oct 2019 00:21

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