Differences Between Natural Sleep and the Anesthetic State

Abstract

The anesthetic state and natural sleep share many neurobiological features and yet are two distinct states. The hallmarks of general anesthesia include hypnosis, analgesia, akinesia and anxiolysis. These are the principal parameters by which the anesthetic state differs from natural sleep. These properties are mediated by systemic administration of a combination of agents producing balanced anesthesia. The exact nature of anesthetic narcosis is dose dependent and agent specific. It exhibits a relative lack of nociceptive response and active suppression of motor and autonomic reflexes. Surgical anesthesia displays a signature electroencephalogram pattern of burst suppression that differs from rapid eye movement sleep, representing more widespread disruption of thalamocortical connectivity, impairing information integration and processing. These differences underpin successful anesthetic action. This review explores the differences between natural sleep and anesthetic-induced unconsciousness as induced by balanced anesthesia.

Anesthetized animal experiments for neuroscience research

“…General anesthesia and natural sleep induce similar behaviors. Therefore, their similarities have been discussed for a long time (Shafer, 1995;Date et al, 2020). The two conditions have both similar and different functional features.…”

Anesthesia-related brain microstructure modulations detected by diffusion MRI

“…isoflurane and ketamine-xylazine) and natural sleep in the context of our findings. In general, anesthesia serves as an excellent tool for inducing unconsciousness and may share many neurobiological processes with natural sleep [47][48][49] . However, anesthesia is not equivalent to natural sleep 50 and comparisons of these states are therefore inevitably flawed.…”

Different Alterations of Hippocampal and Reticulo-Thalamic GABAergic Parvalbumin-Expressing Interneurons Underlie Different States of Unconsciousness

“…The anesthetic state and natural sleep share many neurobiological features, yet they are distinct states [ 1 , 2 , 3 , 4 ]. While the anesthetic state is a pharmacologically induced, reversible state of unconsciousness, sleep is endogenously generated and involves the active suppression of consciousness by nuclei in the brainstem, diencephalon, and basal forebrain, and is dependent on homeostatic drive and circadian rhythm [ 5 ]. In contrast with sleep, in which there is a regular switch between non-rapid eye movement (NREM) and rapid eye movement (REM) sleep, once NREM sleep is established, in anesthesia at steady-state concentration, there is an alternation of brain states expressed by EEG oscillations that vary between delta, theta, alpha, and burst suppression [ 6 , 7 ].…”

“…Anesthesia and sleep onset may differ in terms of the neurotransmitters and molecular targets involved, as well as the anesthetic used [ 5 ]. It has been suggested that the type of GABAergic inhibition observed in both sleep and anesthesia has subtle variation in terms of the preferred subunit of the GABA receptor as a target, as well as the differential distribution of the subunit throughout the central nervous system, which may determine the site of action of anesthetics and natural somnogens [ 5 ]. Evidence suggests that neurons controlling the sleep−wake states (VLPO/MnPO GABAergic or glutamatergic neurons) do not necessarily mediate general anesthesia [ 4 ].…”

“…Evidence suggests that neurons controlling the sleep−wake states (VLPO/MnPO GABAergic or glutamatergic neurons) do not necessarily mediate general anesthesia [ 4 ]. Apart from showing changes in EEG morphology with increasing depth of anesthesia and sleep that are typical of both sleep and surgical anesthesia, the anesthetic state shows a reduction in cerebral metabolism, a complete absence of nociceptive responses, a loss of protective reflexes (cough and gag reflex), and reduced postural control compared with sleep [ 5 ]. In addition, sleep, although characterized by amnesia like anesthesia, is thought to play a key role in memory consolidation and cognitive development [ 20 , 21 ].…”