ENTRIES A–Z
Philip Winn in Dictionary of Biological Psychology, 2003
Slow-wave sleep refers to quiet sleep in the mammal during which slow waves are recorded from the ELECTROENCE-PHALOGRAM (EEG). These slow waves range in frequency from 0.1 to 4 Hz. The waves from 1 to 4 Hz are termed DELTA WAVES, whereas more recently the waves below 1 Hz have been termed the slow oscillation. In fact, the delta waves ride on top of the slow oscillation. Slow waves increase in incidence and amplitude in a progression from sleep onset to the full development of slow wave sleep and thus in what has been divided into four stages in humans. In addition, another activity which occurs at a higher frequency (12-14 Hz) and with increasing then decreasing amplitude to form a spindle-like shape evoking the name SLEEP SPINDLE, occurs in the early stages of sleep. Thus in humans, a loss of alpha activity (marking relaxed wakefulness) occurs in stage 1, spindles riding on slower waves in stage 2 and a progressive increase in delta riding on slower waves in stages 3 and 4. Slow-wave sleep is referred to as QUIET SLEEP because there are few movements in deep slow-wave sleep, in contrast to REM SLEEP, when the eyes move and the extremities twitch or move. In addition, it was originally believed that no mental activity occurred during slow-wave sleep, in contrast to REM sleep, when DREAMING was shown to occur. However subsequent studies found that mental activity does occur in slow-wave sleep. This sleep mentation is reported as dream-like but described as less vivid and bizarre than the dreams of REM sleep.
The Sleeping Brain
Hanno W. Kirk in Restoring the Brain, 2020
Research has indicated that sleep spindles, which represent bursting activity of thalamocortical relay neurons, are associated with decreased activity of gamma motor neurons in the cat.61 Moreover, patients with spinal cord injury have elevated SMR activity, attributable to reduced afferent input to thalamus.62 SMR amplitudes and spindle-burst activity are severely reduced in some patients with epilepsy, but increases significantly following SMR training.63 Spindles have also been associated with increases in auditory threshold during NREM sleep.64 Conversely, differential sound oscillations which target sub-populations of spindles during NREM sleep, 11–13.5 Hz frontally and 13.5–16 Hz more posteriorly, have been found to affect the distribution of fast and slow spindles only in parietal areas.65 These observations suggest that spindle bursts of N2 sleep correspond to a gating mechanism of sensory input and associated motor output of the central nervous system. Depending on the stimulus or sensory data involved, whether during wakefulness or sleep, spindles may interrupt input into the thalamus and the red nucleus, which is required for motoric activity, whether physiologic, such as walking, or pathologic, as in the case of epilepsy.
Sleep Alterations in Schizophrenia
S.R. Pandi-Perumal, Meera Narasimhan, Milton Kramer in Sleep and Psychosomatic Medicine, 2017
In recent years, there has been an increasing understanding of the possible functions of SWS, REM sleep, and sleep spindles. SWS is characterized by large-amplitude, low-frequency electroencephalographic (EEG) rhythms, mainly occurring during the early part of sleep. The slow waves in SWS are associated with large-scale spatiotemporal synchrony across the neocortex, and are thought to be generated predominantly in the prefrontal cortex.6,7 The SWS has been seen as reflecting overall synaptic density in the human cerebral cortex, in particular that of the prefrontal cortex,8 although this has been recently debated9; deficits in SWS have therefore been thought to reflect parallel prefrontal cortical dysfunction.7 Sleep deprivation in healthy subjects appears to cause impairments in sustained attention that closely resemble prefrontal cortical dysfunction.10 SWS may be involved in restorative activity, reversing the “wear and tear” caused during wakefulness; there is evidence for increased protein synthesis during this sleep phase.11,12
Sleep Behaviors and Handedness in Gifted and Non-Gifted Children
Published in Developmental Neuropsychology, 2021
Joseph M. Piro, Camilo Ortiz, Lynne Manouvrier
Other studies have looked at sleep spindles, which are brief bursts of brainwave activity occurring, typically, during stage 2 sleep and visible on an EEG, as a physiological biomarker of fluid and crystallized intelligence and a window into cortical ability (Gruber et al., 2013; Ricci et al., 2021). In a study by Ujma, Sándor, Szakadát, Gombos, and Bódizs (2016), which examined the relationship between sleep spindles and intelligence in young children (n=28 children; range 4–8years of age; 54% girls), some provocative findings emerged. Results demonstrated that while the presence of sleep spindles in males might best function as a maturational marker, in females they might be an indication of trait-like intelligence. Hoedlmoser et al. (2014) also discovered higher slow spindle activity among 63 children (55% boys) who scored in the upper ranges of the Wechsler Intelligence Scale for Children (WISC-IV) leading them to assert that spindle activity “in children is strongly associated with general cognitive abilities as measured by the WISC-IV” (p. 1508). Outside of studies such as these, sleep behaviors in young gifted children remains an underexplored research topic
Sleep-promoting activity of lotus (Nelumbo nucifera) rhizome water extract via GABAA receptors
Published in Pharmaceutical Biology, 2022
Yejin Ahn, Singeun Kim, Chunwoong Park, Jung Eun Kim, Hyung Joo Suh, Kyungae Jo
Currently, the understanding on how stress affects sleep is obscure, but is suspected to be closely related to sleep and the activity of the hypothalamic-pituitary-adrenal (HPA) axis. In the early stages of sleep, slow wave sleep is dominant, and the activity of the HPA axis is the lowest and continuously suppressed. Conversely, in the second half of sleep, REM sleep dominates and the activity of HPA secretion increases, approaching a daily maximum immediately after waking up. The ventrolateral preoptic nucleus (VLPO) located in the hypothalamus acts as a switch to initiate sleep. Activated VLPO neurons secrete inhibitory neurotransmitters, such as GABA, to inhibit the areas responsible for arousal and induce sleep (Saper etal. 2005). GABAs are activated during sleep and inhibit monoamine and histamine-secreting regions to prevent waking. The thalamic reticular nucleus also contains GABA as a neurotransmitter and generates sleep spindles (Mignot etal. 2002).
Disorders of sleep and wakefulness in amyotrophic lateral sclerosis (ALS): a systematic review
Published in Amyotrophic Lateral Sclerosis and Frontotemporal Degeneration, 2021
Diana Lucia, Pamela A. McCombe, Robert D. Henderson, Shyuan T. Ngo
The studies without controls also reported impairments to sleep microstructure and architecture among ALS patients. A study in 2009 (7) confirmed sleep abnormalities in all eleven patients assessed. Normal REM sleep was only observed in three patients, and this was independent of diaphragmatic function. A subsequent study (22) reported the absence of sleep spindles in four out of eight patients, and irregular non REM and REM sleep in all patients. A 2019 study assessing sleep in 42 ALS patients reported significant sleep alterations in all patients, with a decrease in total sleep time and sleep efficiency, an increase in nocturnal awakenings, and reduced REM sleep (23). Finally, a study of polysomnograms in 12 ALS patients (14) revealed increased sleep latency, reduced slow-wave sleep, as well as reduced and fractured REM stages, and reduced sleep efficiency.
