Search Results (74)

Artificial light exposure, particularly from blue-rich sources, has raised concerns about its impact on sleep and circadian rhythms. While blue light’s effects are well-documented, the comparative impact of longer wavelengths, such as orange light (590–635 nm), remains underexplored. This study investigated the effects of 8 h blue (470–490 nm) and orange light exposures (500 lux) on sleep architecture in the next consecutive three days in Sprague-Dawley rats during the light or dark phase of a 12:12 h light–dark cycle. Sleep–wake states were assessed via electroencephalography (EEG) over 72 h. Blue light during the light period suppressed rapid eye movement (REM) sleep acutely and enhanced non-NREM sleep on Days 2 and 3. Orange light during the light period induced no immediate changes but increased NREM sleep on Day 2 with a biphasic REM response—suppression followed by rebound—persisting into Day 3. Blue light during the dark period increased NREM sleep during exposure, followed by suppression in the subsequent light period, with effects normalizing by Day 2. Blue light exposure suppressed melatonin levels compared to controls. These findings highlight spectral and temporal influences on sleep, with blue light exerting stronger acute effects and orange light eliciting delayed, biphasic responses. The results suggest implications for managing light exposure to mitigate sleep disruptions in modern environments. Full article

Background: Sleep difficulty is common in the current society. Poor sleep has a significant influence on health, social interactions and even mortality; therefore, maintaining good sleep is of prime importance. Cannabidiol (CBD), a cannabis-derived compound, is known for its medical significance with many positive effects in humans, including decreasing anxiety and improving sleep for those with sleep disorders. Objective: However, whether CBD skin absorption results in similar effects is unknown. Therefore, examining CBD-coated fabric as a pillow cover to improve sleep quality in duty shift nurses is the purpose of this paper. Methods: This study recruited 55 duty shift nurses as participants to evaluate sleep patterns and quality using the Pittsburgh Sleep Quality Index (PSQI) and a consumer-grade tracker (Fitbit Charge 3). Data were collected over three phases: a one-week baseline period, a two-week intervention period using a CBD-coated pillow cover and a one-week follow-up period, referred to as the post-intervention phase, during which the use of CBD-coated pillow cover was continued. Results: Of the 55 participants, 10 were men (18.2%) and 45 were women (81.8%). At baseline, all participants exhibited poor sleep quality (PSQI ≥ 5). However, after three weeks of using CBD-coated pillow covers, subjective sleep quality significantly improved, with 7.3% of participants achieving PSQI scores <5. Additionally, slight changes in sleep patterns were observed, with increases in both light sleep and deep sleep durations. Light sleep duration increased from a baseline of 196.21 ± 65.28 to 206.57 ± 59.15 min two weeks after intervention (p = 0.337). Similarly, deep sleep duration showed a modest increase from 61.97 ± 21.01 min to 64.35 ± 22.19 min (p = 0.288). Furthermore, a significant reduction in anxiety levels was reported (p < 0.005). Conclusions: Using a CBD-coated pillow cover was found to enhance sleep duration in healthy individuals experiencing poor sleep. Consequently, for adults struggling with sleep difficulties, incorporating a CBD-coated pillow cover may serve as an effective aid in improving sleep quality. Full article

Accurate identification of sleep stages is essential for understanding sleep physiology and its role in neurological and behavioral research. Manual scoring of polysomnographic data, while reliable, is time-intensive and prone to variability. This study presents a novel Python-based algorithm for automated vigilance state scoring using single-channel electroencephalogram (EEG) recordings from rats and mice. The algorithm employs artifact processing, multi-band frequency analysis, and Gaussian mixture model (GMM)-based clustering to classify wakefulness, non-rapid, and rapid eye movement sleep (NREM and REM sleep, respectively). Combining narrow and broad frequency bands across the delta, theta, and sigma ranges, it uses a majority voting system to enhance accuracy, with tailored preprocessing and voting criteria improving REM detection. Validation on datasets from 10 rats and 10 mice under standard conditions showed sleep–wake state detection accuracies of 92% and 93%, respectively, closely matching manual scoring and comparable to existing methods. REM sleep detection accuracies of 89% (mice) and 91% (rats) align with previously reported (85–90%). Processing a full day of EEG data within several minutes, the algorithm is advantageous for large-scale and longitudinal studies. Its open-source design, flexibility, and scalability make it a robust, efficient tool for automated rodent sleep scoring, advancing research in standard experimental conditions, including aging and sleep deprivation. Full article

Background/Objectives: Serotonin and the serotonin transporter (SERT) may have a multifaceted, but not fully understood, role in obstructive sleep apnea (OSA) and its impact on mental health in this group of patients. This study aimed to investigate changes in serotonin and the serotonin transporter (SERT) and their association with depressive and insomnia symptoms. Methods: This study included 76 participants (OSA group: n = 36, control group (CG): n = 40) who underwent polysomnography, while venous blood samples (evening and morning) were analyzed for serotonin and the SERT using ELISA. SERT mRNA expression in peripheral leukocytes was measured via quantitative reverse-transcription polymerase chain reaction (qRT-PCR). Participants were evaluated for depression, insomnia, and quality of life (QoL). Results: This study found no significant differences in SERT mRNA or serotonin between the OSA group and CG. In the CG, individuals without mood disorders had higher baseline SERT levels and evening/morning SERT ratios than those with depression. Among the OSA participants, those with good QoL had elevated serotonin levels in the evening (p = 0.028) and morning (p = 0.043) compared to those with poor QoL. Baseline SERT protein levels were higher in the CG than in the OSA group for insomnia, while SERT mRNA expression was higher in the OSA group. Linear regression models showed 13.3% and 13.1% for non-rapid eye movement sleep (NREM) apnea/hypopnea index (AHI) and AHI variability, respectively, which was accounted for by the morning SERT level, while 30.8% of the arousal index variability was explained by the morning serotonin level. Conclusions: Serotonergic signaling may influence quality of life, depression, and insomnia in OSA, as well as the severity of the disease itself. Stratifying patients by clinical and laboratory phenotypes could enable more personalized treatment. Full article

(1) Background: Gamma-aminobutyric acid (GABA) is an amino acid and the primary inhibitory neurotransmitter in the brain. GABA has been shown to reduce stress and promote sleep. GABALAGEN (GBL) is the product of fermented fish collagen by Lactobacillus brevis BJ20 and Lactobacillus plantarum BJ21, naturally enriched with GABA through the fermentation process and characterized by low molecular weight. (2) Methods: The present study evaluated the GABA_A affinity of GBL through receptor binding assay. The sedative effects of GBL were investigated through electroencephalography (EEG) analysis in an animal model of electro foot shock (EFS) stress-induced sleep disorder, and then we examined the expression of orexin and the GABA_A receptor in the brain region using immunohistochemistry and an enzyme-linked immunosorbent assay (ELISA). (3) Results: We found that on the binding assay, GBL displayed high affinity to the GABA_A receptor. Also, after treatment with GBL, the percentage of the total time in rapid eye movement (REM) and non-rapid eye movement (NREM) sleep was significantly and dose-dependently increased in EFS-induced rats. Consistent with behavioral results, the GBL-treated groups showed that the expression of GABA_A receptor immune-positive cells in the VLPO was markedly and dose-dependently increased. Also, the GBL-treated groups showed that the expression of the orexin-A level in LH was significantly decreased. (4) Conclusions: GBL showed efficacy and potential to be used as an anti-stress therapy to treat sleep deprivation through the stimulation of GABA_A receptors and the consequent inhibition of orexin activity. Full article

Background: Sleep, a process physiologically vital for mental health, faces disruptions in various sleep disorders linked to metabolic and neurodegenerative risks. Zizyphus seed (Zizy) has long been recognized for its diverse pharmacological attributes, including analgesic, sedative, insomnia, and anxiety alleviation. Objectives: In this study, the sleep-prolonging effects of Zizy extract (100, 200 mg/kg), along with their characterizing compounds jujuboside A (JuA) (5, 10 mg/kg), were evaluated in a mouse model under a pentobarbital-induced sleep. Additionally, the efficacy of Zizy extract was examined on caffeine-induced insomnia in mice. Methods: To confirm the efficacy of Zizy extract on the structure and quality of sleep, an electroencephalogram (EEG) analysis of rats was performed using the MATLAB algorithm. Additionally, Western blot analysis and measurement of intracellular chloride influx were performed to confirm whether these effects acted through the gamma-aminobutyric acid (GABA)ergic system. Administration of Zizy extract showed no effect on the locomotor performance of mice, but the extract and their characteristic compounds significantly prolonged sleep duration in comparison to the pentobarbital alone group in the pentobarbital-induced sleep mouse model. Furthermore, this extract alleviated caffeine-induced insomnia in mice. Results: The administration of Zizy extract extended non-rapid eye movement sleep (NREMS) duration without inducing significant changes in the brain wave frequency. Zizy extract regulated the expression of GABA_A receptor subunits and GAD65/67 in specific brain regions (frontal cortex, hippocampus, and hypothalamus). JuA increased intracellular chloride influx in human SH-SY5Y cells, and it was reduced by GABA_A receptor antagonists. These results suggest that the sleep-maintaining effects of Zizy extract may entail GABAergic regulation. In summary, Zizy extract demonstrated sleep-prolonging properties, improved insomnia, and regulated sleep architecture through GABAergic system modulation. Conclusions: These findings suggest that Zizy extract has potential as a therapeutic agent for stress-related neuropsychiatric conditions such as insomnia. Full article

This study presents the development of a wireless in-ear EEG device designed to monitor brain activity during sleep and deliver auditory stimuli aimed at enhancing deep sleep. The device records EEG signals and plays a combined auditory stimulus consisting of autonomous sensory meridian response (ASMR) and 3 Hz binaural beats at a 60:30 dB ratio, intended to promote delta wave activity and non-rapid eye movement (NREM) stage 3 sleep. Fifteen participants completed this study, which included two consecutive nights: a baseline night and a testing night. Participants were divided into an experimental group, which received the combined ASMR and binaural beat stimulus, and a control group, which received only ASMR. The combined stimulus was delivered upon entering NREM stage 2 and replaced by ASMR when NREM stage 3 was reached. Results showed that the experimental group experienced an increase in NREM 3 sleep, a decrease in NREM 2 sleep, and a slight increase in NREM 3 latency compared to the baseline night. Although the findings are promising, further testing with a larger sample size is required to confirm the device’s potential to enhance sleep quality and promote delta activity in the brain. Full article

The classical function of the mineralocorticoid receptor (MR) is to maintain electrolytic homeostasis and control extracellular volume and blood pressure. The MR is expressed in the central nervous system (CNS) and is involved in the regulation of the hypothalamic–pituitary–adrenal (HPA) axis as well as sleep physiology, playing a role in the non-rapid eye movement (NREM) phase of sleep. Some patients with psychiatric disorders have very poor sleep quality, and a relationship between MR dysregulation and this disorder has been found in them. In addition, the MR is involved in the regulation of the renal peripheral clock. One of the most common comorbidities observed in patients with chronic kidney disease (CKD) is poor sleep quality. Patients with CKD experience sleep disturbances, including reduced sleep duration, sleep fragmentation, and insomnia. To date, no studies have specifically investigated the relationship between MR activation and CKD-associated sleep disturbances. However, in this review, we analyzed the environment that occurs in CKD and proposed two MR-related mechanisms that may be responsible for these sleep disturbances: the circadian clock disruption and the high levels of MR agonist observed in CKD. Full article

Deprivation of sleep (DS) and its effects on circadian rhythm gene expression are not well understood despite their influence on various physiological and psychological processes. This study aimed to elucidate the changes in the expression of circadian rhythm genes following a night of sleep and DS. Their correlation with sleep architecture and physical activity was also examined. The study included 81 participants who underwent polysomnography (PSG) and DS with actigraphy. Blood samples were collected after PSG and DS. Expression levels of brain and muscle ARNT-like 1 (BMAL1), circadian locomotor output cycles kaput (CLOCK), neuronal PAS domain protein 2 (NPAS2), period 1 (PER1), cryptochrome 1 (CRY1) and nuclear receptor subfamily 1 group D member 1 (NR1D1) were analyzed using qRT-PCR. DS decreased the expression of CLOCK and BMAL1 while increasing PER1. PER1 expression correlated positively with total sleep time and non-rapid-eye-movement (NREM) sleep duration and negatively with sleep latency, alpha, beta and delta waves in the O1A2 lead. Physical activity during DS showed positive correlations with CLOCK, BMAL1, and CRY1. The findings highlight the role of PER1 in modulating sleep patterns, suggesting potential targets for managing sleep-related disorders. Further research is essential to deepen the understanding of these relationships and their implications. Full article

Grounding, a therapeutic technique involving direct contact with the earth, has been proposed by various studies to potentially have beneficial effects on pressure, sleep quality, stress, inflammation, and mood. However, the scientific evidence supporting its sedative effects remains incomplete. This study examined the sedative effectiveness of an earthing mat on sleep quality and investigated the underlying neural mechanisms using electroencephalography (EEG) analysis in rodents, focusing on orexin and superoxide dismutase (SOD) levels in the brain. Rats were randomly assigned to four groups: the naïve normal group (Nor), the group exposed to an earthing mat for 7 days (A-7D), the group exposed to an earthing mat for 21 days (A-21D), and the group exposed to an electronic blanket for 21 days (EM). EEG results revealed that the A-21D group exhibited significantly reduced wake time and increased rapid eye movement (REM), non-rapid eye movement (NREM), and total sleep time compared to the Nor group (p < 0.05). Moreover, the A-21D group demonstrated a significant increase in NREM sleep (p < 0.001), REM sleep (p < 0.01), and total sleep time (p < 0.001), along with a decrease in wake time compared to the EM group (p < 0.001). The orexin level in the A-21D group was significantly lower compared to the Nor group (p < 0.01), while SOD1 expression was markedly elevated in the A-21D group compared to the Nor group (p < 0.001). These results suggest that the earthing mat may represent a promising new method for promoting sleep quality and could serve as an effective therapeutic technique. Full article

Robust evidence suggests that the glymphatic system plays a key role in preserving brain health. Indeed, its activity in maintaining homeostasis by clearing neurotoxic proteins such as beta-amyloid from the human brain is essential. Sleep represents the factor that mainly influences this system, since it is selectively active during the night, in particular during non-rapid eye movement (NREM) sleep. This is true, since the sleep head position, in particular the supine position for its relationship to the status of opening/closing of the jugular veins, appears to be determinant for the development of future neurodegeneration. Growing evidence from human and animal models highlights the neurobiological link between sleep, glymphatic dysfunction and neurodegeneration. On the other hand, several modifiable factors have been recently identified modulating (improve/reduce) glymphatic system activity, such as Omega-3 polyunsaturated fatty acids, stress, hypertension, physical activity, alcohol, gender and genetic predisposition, in particular variants of aquaporin-4 (AQP4). From this viewpoint, our ambition is to discuss how the glymphatic system works in the brain, what factors mainly impact on this activity and its strict relation with the neurodegeneration. Future directions might include the analysis of factors modulating glymphatic system activity and a personalized glymphatic profile, “glymphatom”, as a natural target for preventive neurodegenerative treatment. Full article

The importance of sleep for healthy brain function is widely acknowledged. However, it remains unclear how the internal generation of dreams might facilitate cognitive processes. In this perspective, we review a computational approach inspired by artificial intelligence that proposes a framework for how dreams occurring during rapid-eye-movement (REM) sleep can contribute to learning and creativity. In this framework, REM dreams are characterized by an adversarial process that, against the dream reality, tells a discriminator network to classify the internally created sensory activity as real. Such an adversarial dreaming process is shown to facilitate the emergence of real-world semantic representations in higher cortical areas. We further discuss the potential contributions of adversarial dreaming beyond learning, such as balancing fantastic and realistic dream elements and facilitating the occurrence of creative insights. We characterize non-REM (NREM) dreams, where a single hippocampal memory is replayed at a time, as serving the complementary role of improving the robustness of cortical representations to environmental perturbations. We finally explain how subjects can become aware of the adversarial REM dreams, but less of the NREM dreams, and how content- and state-awareness in wake, dream, and lucid dreaming may appear. Full article

Background: The molecular underpinnings of insufficient sleep remain underexplored, with disruptions in the neurotrophic signaling pathway emerging as a potential explanation. Neurotrophins (NTs), including brain-derived neurotrophic factor (BDNF), neurotrophin-3 (NT3), neurotrophin 4 (NT4), and glial-cell-line-derived growth factor (GDNF), play crucial roles in nerve cell growth and repair. However, their associations with sleep patterns are poorly understood. This study aimed to investigate the relationship between the chosen neurotrophins and objective sleep parameters. Methods: The study involved 81 participants subjected to polysomnography (PSG). Blood samples were collected after PSG. The mRNA expression and serum protein concentrations of BDNF, GDNF, NT3, and NT4 were measured using real-time quantitative reverse-transcription PCR (qRT-PCR) or enzyme-linked immunosorbent assay (ELISA) methods, respectively. Results: BDNF and NT3 proteins were negatively correlated with NREM events, while NT4 protein positively correlated with REM events. Electroencephalography power analysis revealed BDNF protein’s negative correlation with delta waves during rapid eye movement and non-rapid eye movement sleep. Conclusion: The study highlights associations between neurotrophins and sleep, emphasizing BDNF’s role in regulating NREM and REM sleep. The EEG power analysis implicated BDNF in delta wave modulation, shedding light on potential neurotrophic mechanisms underlying sleep effects on cognitive and mood processes. Full article

When we are asleep, we lose the ability to promptly respond to external stimuli, and yet we spend many hours every day in this inherently risky behavioral state. This simple fact strongly suggests that sleep must serve essential functions that rely on the brain going offline, on a daily basis, and for long periods of time. If these functions did not require partial sensory disconnection, it would be difficult to explain why they are not performed during waking. Paradoxically, despite its central role in defining sleep and what sleep does, sensory disconnection during sleep remains a mystery. We have a limited understanding of how it is implemented along the sensory pathways; we do not know whether the same mechanisms apply to all sensory modalities, nor do we know to what extent these mechanisms are shared between non-rapid eye movement (NREM) sleep and REM sleep. The main goal of this contribution is to review some knowns and unknowns about sensory disconnection during sleep as a first step to fill this gap. Full article

Transcranial direct current stimulation (tDCS) is acknowledged for its non-invasive modulation of neuronal activity in psychiatric disorders. However, its application in insomnia research yields varied outcomes depending on different tDCS types and patient conditions. Our primary objective is to elucidate its efficiency and uncover the underlying mechanisms in insomnia treatment. We hypothesized that anodal prefrontal cortex stimulation activates glutamatergic projections from the infralimbic cortex (IL) to the ventrolateral preoptic area (VLPO) to promote sleep. After administering 0.06 mA of electrical currents for 8 min, our results indicate significant non-rapid eye movement (NREM) enhancement in naïve mice within the initial 3 h post-stimulation, persisting up to 16–24 h. In the insomnia group, tDCS enhanced NREM sleep bout numbers during acute stress response and improved NREM and REM sleep duration in subsequent acute insomnia. Sleep quality, assessed through NREM delta powers, remains unaffected. Interference of the IL-VLPO pathway, utilizing designer receptors exclusively activated by designer drugs (DREADDs) with the cre-DIO system, partially blocked tDCS’s sleep improvement in stress-induced insomnia. This study elucidated that the activation of the IL-VLPO pathway mediates tDCS’s effect on stress-induced insomnia. These findings support the understanding of tDCS effects on sleep disturbances, providing valuable insights for future research and clinical applications in sleep therapy. Full article