In: Bassetti C, McNicholas W, Paunio T, Peigneux P (eds) Sleep Medicine Textbook, 2nd ed. European Sleep Research Society, 2021, pp. 41-56.
Summary
The beneficial effects of sleep are manifold. The present chapter provides knowledge on the function of sleep by an overview of the major principles and methodological approaches, as well as the leading theories in the field. Theoretical proposals range from the appropriate timing of activity (ecological hypothesis), through rest (energy conservation), recovery (detoxification, restoration of frontal lobe functions and mood), neural plasticity/memory consolidation (rapid eye movement sleep-centred hypothesis, two-stage model, system and synaptic consolidation), and neural network maintenance (reverse learning, neuronal group theory, dynamic stabilization, synaptic homeostasis hypothesis) to immune system functions (sleep-to-immune interactions). Several specific theories formulate similar conceptual backgrounds and predictions, whereas others are contradictory in terms of the nature and functional significance of sleep. The idea of a multilevel functional system is proposed, according to which the functions of sleep were multiplied during phylogeny, embedding the new evolutionary achievements of thermoregulation and complex central nervous systems.
Keywords
adaptive immunity, adaptive inactivity, energy metabolism, executive functions, functional hypotheses, metabolic waste, mood regulation, synaptic downscaling, system consolidation