Subterranean Fishes of the World

5648

2019

Handbook of Behavioral Neuroscience

363-374

30

Sleep is essential to nearly all studied animals to date, ranging from animals with simplified neural networks like jellyfish to those with the complex nervous system of mammals ( Joiner, 2016; Nath et al., 2017). In humans, prolonged sleep deprivation has negative health consequences, including metabolic dysregulation and death, while inadequate sleep results in reduced alertness; dysregulation of many cognitive functions, including learning and memory; and compromised health (Arble et al., 2015; Knutson & Van Cauter, 2008). It is estimated that about 30% of the world population suffers from some type of sleep disturbances (Ferrie, Kumari, Salo, Singh-Manoux, & Kivim€aki, 2011). Despite more than a century of systematic research, the function and biological mechanism of sleep regulation remain poorly understood (Hartmann, 1973). Diverse theories have been postulated to account for the restorative effect of sleep, including ecological adaptation, macromolecule biosynthesis, energy conservation, metabolite clearance, synaptic plasticity, and memory consolidation (Schmidt, 2014; Siegel, 2005; Tononi & Cirelli, 2014; Xie et al., 2013). Nevertheless, a key question remains unanswered: Why do sleep timing and duration vary dramatically among different species, and what are the fundamental functions subserved by the evolution of sleep? While sleep has long been recognized as a widely conserved behavior, sleep studies have historically focused on mammalian systems (Hartmann, 1973). Recently, sleep has been characterized in a number of fish species that provide novel avenues for investigating the function and mechanistic underpinnings of sleep (Duboue, Keene, & Borowsky, 2011; Prober, Rihel, Onah, Sung, & Schier, 2006; Yokogawa et al., 2007; Zhdanova, Wang, Leclair, & Danilova, 2001). Studying evolutionarily conserved components of sleep in various animal models, such as these relatively simple vertebrates, could provide fundamental insights into the functions and mechanisms of sleep.

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