Sleep-Wake Neurochemistry

Individualized approaches to pediatric chronic insomnia: Advancing precision medicine in sleep disorders

The manifestations of chronic insomnia undergo age-related changes. In younger infants and children, behavioral insomnia emerges as the most prevalent form and typically responds to behavioral interventions. However, distinct clusters of clinical presentations suggest the presence of various phenotypes, potentially implicating the primary involvement of specific neurotransmitters. These conceptualizations, coupled with genetic studies on pleiotropy and polygenicity, may aid in identifying individuals at risk of persistent insomnia into adulthood and shed light on novel treatment options. In school-age children, the predominant presentation is sleep-onset insomnia, often linked with nighttime fears, anxiety symptoms, poor sleep hygiene, limit-setting issues, and inadequate sleep duration. The manifestations of insomnia in adolescence correlate with the profound changes occurring in sleep architecture, circadian rhythms, and homeostatic processes. The primary symptoms during adolescence include delayed sleep onset, sleep misperception, persistent negative thoughts about sleep, and physiological hyperarousal-paralleling features observed in adult insomnia. An approach centered on distinct presentations may provide a framework for precision-based treatment options. Enhanced comprehension of insomnia's manifestations across diverse developmental stages can facilitate accurate assessment. Efforts to subtype insomnia in childhood align with this objective, potentially guiding the selection of appropriate treatments tailored to individual neurobiological, clinical, and familial features.

The enigma of sleep: Implications of sleep neuroscience for the dental clinician and patient

BACKGROUND

Sleep disturbances have been shown to result in considerable morbidity and mortality. It is important for dental clinicians to understand the neuroscience behind sleep disorders.

TYPES OF STUDIES REVIEWED

The authors conducted a search of the literature published from January 1990 through March 2024 of sleep medicine-related articles, with a focus on neuroscience. The authors prioritized articles about the science of sleep as related to dental medicine.

RESULTS

The authors found a proliferation of articles related to sleep neuroscience along with its implications in dental medicine. The authors also found that the intricate neuroscientific principles of sleep medicine are being investigated robustly. The salient features of, and the differences between, central and obstructive sleep apneas have been elucidated. Sleep genes, such as CRY, PER1, PER2, and CLOCK, and their relationship to cancer and neurodegeneration are also additions to this rapidly developing science.

CONCLUSIONS AND PRACTICAL IMPLICATIONS

The dental clinician has the potential to be the first to screen patients for possible sleep disorders and make prompt referrals to the appropriate medical professionals. This can be lifesaving as well as minimize potential future morbidity for the patient.

Neurotransmitters: Impressive regulators of tumor progression

In contemporary times, tumors have emerged as the primary cause of mortality in the global population. Ongoing research has shed light on the significance of neurotransmitters in the regulation of tumors. It has been established that neurotransmitters play a pivotal role in tumor cell angiogenesis by triggering the transformation of stromal cells into tumor cells, modulating receptors on tumor stem cells, and even inducing immunosuppression. These actions ultimately foster the proliferation and metastasis of tumor cells. Several major neurotransmitters have been found to exert modulatory effects on tumor cells, including the ability to restrict emergency hematopoiesis and bind to receptors on the postsynaptic membrane, thereby inhibiting malignant progression. The abnormal secretion of neurotransmitters is closely associated with tumor progression, suggesting that focusing on neurotransmitters may yield unexpected breakthroughs in tumor therapy. This article presents an analysis and outlook on the potential of targeting neurotransmitters in tumor therapy.

Fundamentals of sleep regulation: Model and benchmark values for fractal and oscillatory neurodynamics

Homeostatic, circadian and ultradian mechanisms play crucial roles in the regulation of sleep. Evidence suggests that ratios of low-to-high frequency power in the electroencephalogram (EEG) spectrum indicate the instantaneous level of sleep pressure, influenced by factors such as individual sleep-wake history, current sleep stage, age-related differences and brain topography characteristics. These effects are well captured and reflected in the spectral exponent, a composite measure of the constant low-to-high frequency ratio in the periodogram, which is scale-free and exhibits lower interindividual variability compared to slow wave activity, potentially serving as a suitable standardization and reference measure. Here we propose an index of sleep homeostasis based on the spectral exponent, reflecting the level of membrane hyperpolarization and/or network bistability in the central nervous system in humans. In addition, we advance the idea that the U-shaped overnight deceleration of oscillatory slow and fast sleep spindle frequencies marks the biological night, providing somnologists with an EEG-index of circadian sleep regulation. Evidence supporting this assertion comes from studies based on sleep replacement, forced desynchrony protocols and high-resolution analyses of sleep spindles. Finally, ultradian sleep regulatory mechanisms are indicated by the recurrent, abrupt shifts in dominant oscillatory frequencies, with spindle ranges signifying non-rapid eye movement and non-spindle oscillations - rapid eye movement phases of the sleep cycles. Reconsidering the indicators of fundamental sleep regulatory processes in the framework of the new Fractal and Oscillatory Adjustment Model (FOAM) offers an appealing opportunity to bridge the gap between the two-process model of sleep regulation and clinical somnology.

Chrysanthemum morifolium and Its Bioactive Substance Enhanced the Sleep Quality in Rodent Models via Cl- Channel Activation

Dried Chrysanthemum morifolium (Chry) flowers have been used in Korea as a traditional insomnia treatment. In this study, the sleep-promoting activity and improving sleep quality of Chry extract (ext) and its active substance linarin were analyzed by pentobarbital-induced sleep experiment in mice and electroencephalography (EEG), electromyogram (EMG) analysis in rats. In a dose-dependent manner, Chry ext and linarin promoted longer sleep duration in the pentobarbital-induced sleep test compared to pentobarbital-only groups at both hypnotic and subhypnotic doses. Chry ext administration also significantly improved sleep quality, as seen in the relative power of low-frequency (delta) waves when compared with the control group. Linarin increased Cl- uptake in the SH-SY5Y human cell line and chloride influx was reduced by bicuculline. After administration of Chry ext, the hippocampus, frontal cortex, and hypothalamus from rodents were collected and blotted for glutamic acid decarboxylase (GAD)65/67 and gamma-aminobutyric acid (GABA)A receptors subunit expression levels. The expression of α1-subunits, β2-subunits, and GAD65/67 of the GABAA receptor was modulated in the rodent brain. In conclusion, Chry ext augments pentobarbital-induced sleep duration and enhances sleep quality in EEG waves. These effects might be due to the activation of the Cl- channel.

Sleep disturbances in Lewy body dementia: A systematic review

BACKGROUND

Lewy body dementia (LBD) refers to both dementia with Lewy bodies (DLB) and Parkinson's disease with dementia (PDD). Sleep disturbances are common in LBD, and can include poor sleep quality, excessive daytime sleepiness (EDS), and rapid eye movement behaviour disorder (RBD). Despite the high clinical prevalence of sleep disturbances in LBD, they are under-studied relative to other dementias. The aim of the present systematic review was to examine the nature of sleep disturbances in LBD, summarise the effect of treatment studies upon sleep, and highlight specific and necessary directions for future research.

METHODS

Published studies in English were located by searching PubMED and PSYCArticles databases (until 10 June 2022). The search protocol was pre-registered in PROSPERO (CRD42021293490) and performed in accordance with PRISMA guidelines.

RESULTS

Following full-text review, a final total of 70 articles were included. These included 20 studies focussing on subjective sleep, 14 on RBD, 8 on EDS, 7 on objective sleep, and 1 on circadian rhythms. The majority of the 18 treatment studies used pharmacological interventions (n = 12), had an open-label design (n = 8), and were of low-to-moderate quality. Most studies (n = 55) included only patients with DLB. Due to the heterogeneity of the studies, we reported a narrative synthesis without meta-analysis.

CONCLUSIONS

At least one form of sleep disturbance may be present in as many as 90% of people with LBD. Subjectively poor sleep quality, excessive daytime sleepiness, and RBD are more common and severe in LBD relative to other dementias.