Regulation of stress-induced sleep fragmentation by preoptic glutamatergic neurons

Factors associated with sleep duration in a Chinese middle-aged and elderly diabetic population: a cross-sectional study

BACKGROUND

The adverse effects of excessively short or long sleep duration on diabetes have been confirmed in previous studies. However, there is a lack of research on the factors associated with sleep duration in diabetic patients, and this study aims to identify the factors associated with sleep duration in diabetes mellitus.

METHODS

This study collected data from 2116 middle-aged and elderly individuals with diabetes mellitus who were surveyed by the China Health and Retirement Longitudinal Study (CHARLS) in 2011 and 2015. Sleep duration was assessed based on patient self-reports, defined as the total amount of sleep patients obtained on average at night over the past month (average nightly sleep duration), it was categorized into short sleep duration (< 6 h), adequate sleep duration (6-9 h) and long sleep duration (> 9 h). Stepwise multivariable multinomial logistic regression was used to explore the associated factors related to short sleep duration (< 6 h) and long sleep duration (> 9 h), using adequate sleep duration as the reference.

RESULTS

The mean self-reported sleep duration in the study sample was (6.34 ± 1.86) hours, with 66.6% reporting adequate sleep duration, 29.6% short sleep duration, and 3.8% long sleep duration. Short sleep duration was positively associated with older age, having low level of education, no health insurance, poor sleep quality, short napping time, and poor self-reported health status. The probability of short sleep duration was lower among good sleep quality (OR = 0.14; 95%CI = 0.11-0.18), good self-reported health status (OR = 0.62; 95%CI = 0.44-0.88). Long sleep duration was positively associated with being male, never smoked, good sleep quality, and traditional Chinese medicine treatment. Long sleep duration was negatively associated with the cognitive function score (OR = 0.94; 95%CI = 0.90-0.99), and having one comorbidity (OR = 0.42; 95%CI = 0.20-0.87).

CONCLUSION

Sleep duration was influenced by a combination of factors among middle-aged and elderly patients with diabetes in China. The study suggested that we should focus on key populations, such as older adults, individuals without health insurance, those with poor sleep quality, low cognitive function and poor self-reported health status, to promote healthy sleep.

Sleep and the recovery from stress

The relationship between stress and sleep is multifaceted, with stress capable of both disrupting and promoting sleep depending on the nature, intensity, and duration of the stressor. While stress commonly leads to sleep fragmentation and arousal in both humans and animals, certain selective stressors, such as immune challenges and psychosocial stress, promote sleep in rodent models. Specific neural circuits, such as those involving the ventral tegmental area and lateral habenula, mediate this stress-induced sleep. Post-stress sleep may facilitate recovery, reduce anxiety, and enhance stress resilience, but the extent to which sleep versus wakefulness post-stress aids long-term adaptation is unclear. Both human and animal studies highlight a bidirectional relationship, where stress-induced changes in sleep architecture may have adaptive or maladaptive consequences. Here, we propose that post-stress sleep contributes to resilience and discuss potential mechanisms underlying this process. A deeper understanding of these pathways may provide new strategies for enhancing stress recovery and improving mental health outcomes.

Serotonin modulates infraslow oscillation in the dentate gyrus during non-REM sleep

Synchronous neuronal activity is organized into neuronal oscillations with various frequency and time domains across different brain areas and brain states. For example, hippocampal theta, gamma, and sharp wave oscillations are critical for memory formation and communication between hippocampal subareas and the cortex. In this study, we investigated the neuronal activity of the dentate gyrus (DG) with optical imaging tools during sleep-wake cycles in mice. We found that the activity of major glutamatergic cell populations in the DG is organized into infraslow oscillations (0.01-0.03 Hz) during NREM sleep. Although the DG is considered a sparsely active network during wakefulness, we found that 50% of granule cells and about 25% of mossy cells exhibit increased activity during NREM sleep, compared to that during wakefulness. Further experiments revealed that the infraslow oscillation in the DG was correlated with rhythmic serotonin release during sleep, which oscillates at the same frequency but in an opposite phase. Genetic manipulation of 5-HT receptors revealed that this neuromodulatory regulation is mediated by Htr1a receptors and the knockdown of these receptors leads to memory impairment. Together, our results provide novel mechanistic insights into how the 5-HT system can influence hippocampal activity patterns during sleep.

Analysis of Sleep Quality Evaluation Factors Affecting Dry Eye Syndrome

Purpose

The purpose of this study was to investigate the relationship between sleep quality and dry eye syndrome, with a specific focus on identifying the sleep-related factors that increase the risk of developing dry eye syndrome.

Patients and Methods

We utilized the PSQI-K (Korean version of the Pittsburgh Sleep Quality Index) and MQ (McMonnies Dry Eye Questionnaire) to assess sleep quality and dry eye syndrome in 221 participants. The seven subfactors of sleep measured were subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbance, use of sleep medication, and daytime dysfunction.

Results

There was a significant correlation between poor sleep quality and higher scores of dry eye syndrome. Factors such as lower subjective sleep quality, longer sleep latency, shorter sleep duration, frequent sleep interruptions, and increased daytime dysfunction were associated with worse dry eye scores. The primary disruptors of sleep included sleep fragmentation and unsuitable thermal environments during sleep.

Conclusion

Sleep disruptions, particularly those caused by modern lifestyle factors such as excessive use of digital devices and mental health issues like depression, anxiety, and stress, significantly contribute to the likelihood of developing dry eye syndrome. Addressing these sleep-disrupting factors through comprehensive management of sleep habits and mental health is crucial for preventing dry eye syndrome. Even in individuals not currently classified with dry eye syndrome, preemptive management of identified risk factors is recommended to mitigate potential future onset.

Anything but small: Microarousals stand at the crossroad between noradrenaline signaling and key sleep functions

Continuous sleep restores the brain and body, whereas fragmented sleep harms cognition and health. Microarousals (MAs), brief (3- to 15-s-long) wake intrusions into sleep, are clinical markers for various sleep disorders. Recent rodent studies show that MAs during healthy non-rapid eye movement (NREM) sleep are driven by infraslow fluctuations of noradrenaline (NA) in coordination with electrophysiological rhythms, vasomotor activity, cerebral blood volume, and glymphatic flow. MAs are hence part of healthy sleep dynamics, raising questions about their biological roles. We propose that MAs bolster NREM sleep's benefits associated with NA fluctuations, according to an inverted U-shaped curve. Weakened noradrenergic fluctuations, as may occur in neurodegenerative diseases or with sleep aids, reduce MAs, whereas exacerbated fluctuations caused by stress fragment NREM sleep and collapse NA signaling. We suggest that MAs are crucial for the restorative and plasticity-promoting functions of sleep and advance our insight into normal and pathological arousal dynamics from sleep.

Circuit mechanism underlying fragmented sleep and memory deficits in 16p11.2 deletion mouse model of autism

Sleep disturbances are prevalent in children with autism spectrum disorder (ASD). Strikingly, sleep problems are positively correlated with the severity of ASD symptoms, such as memory impairment. However, the neural mechanisms underlying sleep disturbances and cognitive deficits in ASD are largely unexplored. Here, we show that non-rapid eye movement sleep (NREMs) is fragmented in the 16p11.2 deletion mouse model of ASD. The degree of sleep fragmentation is reflected in an increased number of calcium transients in the activity of locus coeruleus noradrenergic (LC-NE) neurons during NREMs. In contrast, optogenetic inhibition of LC-NE neurons and pharmacological blockade of noradrenergic transmission using clonidine consolidate sleep. Furthermore, inhibiting LC-NE neurons restores memory. Finally, rabies-mediated screening of presynaptic neurons reveals altered connectivity of LC-NE neurons with sleep- and memory-regulatory regions in 16p11.2 deletion mice. Our findings identify a crucial role of the LC-NE system in regulating sleep stability and memory in ASD.

Ultrasound Neuromodulation for Sleep and Neurological Disorder Therapy: A Path to Clinical Translation

Ultrasound neuromodulation is a promising noninvasive technique capable of penetrating the skull and precisely targeting deep brain regions with millimeter accuracy. Recent studies have demonstrated that transcranial ultrasound stimulation (TUS) of sleep-related brain areas can induce sleep in mice and even trigger a reversible, hibernation-like state without causing damage. Beyond its utility in preclinical models of central nervous system diseases, such as epilepsy, tremors, Alzheimer's disease, and depression, TUS holds significant potential for clinical translation. Given that many neurological disorders, including Alzheimer's and Parkinson's disease, are associated with sleep abnormalities, leveraging clinical TUS applications for these diseases also creates a pathway for translating this technology to sleep modulation in human use. These findings highlight the potential for ultrasound neuromodulation to advance neuroscience research and clinical applications in sleep control.

Nucleus Accumbens Corticotropin-Releasing Hormone Neurons Projecting to the Bed Nucleus of the Stria Terminalis Promote Wakefulness and Positive Affective State

The nucleus accumbens (NAc) plays an important role in various emotional and motivational behaviors that rely on heightened wakefulness. However, the neural mechanisms underlying the relationship between arousal and emotion regulation in NAc remain unclear. Here, we investigated the roles of a specific subset of inhibitory corticotropin-releasing hormone neurons in the NAc (NAcCRH) in regulating arousal and emotional behaviors in mice. We found an increased activity of NAcCRH neurons during wakefulness and rewarding stimulation. Activation of NAcCRH neurons converts NREM or REM sleep to wakefulness, while inhibition of these neurons attenuates wakefulness. Remarkably, activation of NAcCRH neurons induces a place preference response (PPR) and decreased basal anxiety level, whereas their inactivation induces a place aversion response and anxious state. NAcCRH neurons are identified as the major NAc projection neurons to the bed nucleus of the stria terminalis (BNST). Furthermore, activation of the NAcCRH-BNST pathway similarly induced wakefulness and positive emotional behaviors. Taken together, we identified a basal forebrain CRH pathway that promotes the arousal associated with positive affective states.

Influence of sleep on physiological systems in atherosclerosis

Sleep is a fundamental requirement of life and is integral to health. Deviation from optimal sleep associates with numerous diseases including those of the cardiovascular system. Studies, spanning animal models to humans, show that insufficient, disrupted or inconsistent sleep contribute to poor cardiovascular health by disrupting body systems. Fundamental experiments have begun to uncover the molecular and cellular links between sleep and heart health while large-scale human studies have associated sleep with cardiovascular outcomes in diverse populations. Here, we review preclinical and clinical findings that demonstrate how sleep influences the autonomic nervous, metabolic and immune systems to affect atherosclerotic cardiovascular disease.

A hypothalamic circuit mechanism underlying the impact of stress on memory and sleep

Stress profoundly affects sleep and memory processes. Stress impairs memory consolidation, and similarly, disruptions in sleep compromise memory functions. Yet, the neural circuits underlying stress-induced sleep and memory disturbances are still not fully understood. Here, we show that activation of CRHPVN neurons, similar to acute restraint stress, decreases sleep and impairs memory in a spatial object recognition task. Conversely, inhibiting CRHPVN neurons during stress reverses stress-induced memory deficits while slightly increasing the amount of sleep. We found that both stress and stimulation of CRHPVN neurons activate neurons in the lateral hypothalamus (LH), and that their projections to the LH are critical for mediating stress-induced memory deficits and sleep disruptions. Our results suggest a pivotal role for CRHPVN neuronal pathways in regulating the adverse effects of stress on memory and sleep, an important step towards improving sleep and ameliorating the cognitive deficits that occur in stress-related disorders.

Excitation-inhibition imbalance in medial preoptic area circuits underlies chronic stress-induced depression-like states

Dysregulation of brain homeostasis is associated with neuropsychiatric conditions such as major depressive disorder. However, underlying neural-circuit mechanisms remain not well-understood. We show in mice that chronic restraint stress (CRS) and social defeat stress (SDS) are both associated with disruption of excitation (E)-inhibition (I) balance, with increased E/I ratios, in medial preoptic area (MPOA) circuits, but through affecting different neuronal types. CRS results in elevated activity in glutamatergic neurons, and their suppression mitigates CRS-induced depressive-like behaviors. Paraventricular hypothalamic input to these neurons contributes to induction but not expression of depressive-like behaviors. Their projections to ventral tegmental area and periaqueductal gray/dorsal raphe suppress midbrain dopaminergic and serotonergic activity, respectively, and mediate expression of divergent depressive-like symptoms. By contrast, SDS results in reduced activity of GABAergic neurons, and their activation alleviates SDS-induced depressive-like behaviors. Thus, E/I imbalance with relatively increased excitation in MPOA circuits may be a general mechanism underlying depression caused by different etiological factors.

Medial preoptic circuits governing instinctive social behaviors

The medial preoptic area (MPOA) has long been implicated in maternal and male sexual behavior. Modern neuroscience methods have begun to reveal the cellular networks responsible, while also implicating the MPOA in other social behaviors, affiliative social touch, and aggression. The social interactions rely on input from conspecifics whose most important modalities in rodents are olfaction and somatosensation. These inputs bypass the cerebral cortex to reach the MPOA to influence the social function. Hormonal inputs also directly act on MPOA neurons. In turn, the MPOA controls social responses via various projections for reward and motor output. The MPOA thus emerges as one of the major brain centers for instinctive social behavior. While key elements of MPOA circuits have been identified, a synthesis of these new data is now provided for further studies to reveal the mechanisms by which the area controls social interactions.

Homeostatic regulation of rapid eye movement sleep by the preoptic area of the hypothalamus

Rapid eye movement sleep (REMs) is characterized by activated electroencephalogram (EEG) and muscle atonia, accompanied by vivid dreams. REMs is homeostatically regulated, ensuring that any loss of REMs is compensated by a subsequent increase in its amount. However, the neural mechanisms underlying the homeostatic control of REMs are largely unknown. Here, we show that GABAergic neurons in the preoptic area of the hypothalamus projecting to the tuberomammillary nucleus (POAGAD2→TMN neurons) are crucial for the homeostatic regulation of REMs in mice. POAGAD2→TMN neurons are most active during REMs, and inhibiting them specifically decreases REMs. REMs restriction leads to an increased number and amplitude of calcium transients in POAGAD2→TMN neurons, reflecting the accumulation of REMs pressure. Inhibiting POAGAD2→TMN neurons during REMs restriction blocked the subsequent rebound of REMs. Our findings reveal a hypothalamic circuit whose activity mirrors the buildup of homeostatic REMs pressure during restriction and that is required for the ensuing rebound in REMs.

Circuit mechanism underlying fragmented sleep and memory deficits in 16p11.2 deletion mouse model of autism

Sleep disturbances are prevalent in children with autism spectrum disorder (ASD) and have a major impact on the quality of life. Strikingly, sleep problems are positively correlated with the severity of ASD symptoms, such as memory impairment. However, the neural mechanisms underlying sleep disturbances and cognitive deficits in ASD are largely unexplored. Here, we show that non-rapid eye movement sleep (NREMs) is highly fragmented in the 16p11.2 deletion mouse model of ASD. The degree of sleep fragmentation is reflected in an increased number of calcium transients in the activity of locus coeruleus noradrenergic (LC-NE) neurons during NREMs. Exposure to a novel environment further exacerbates sleep disturbances in 16p11.2 deletion mice by fragmenting NREMs and decreasing rapid eye movement sleep (REMs). In contrast, optogenetic inhibition of LC-NE neurons and pharmacological blockade of noradrenergic transmission using clonidine reverse sleep fragmentation. Furthermore, inhibiting LC-NE neurons restores memory. Rabies-mediated unbiased screening of presynaptic neurons reveals altered connectivity of LC-NE neurons with sleep- and memory regulatory brain regions in 16p11.2 deletion mice. Our findings demonstrate that heightened activity of LC-NE neurons and altered brain-wide connectivity underlies sleep fragmentation in 16p11.2 deletion mice and identify a crucial role of the LC-NE system in regulating sleep stability and memory in ASD.

Circuit mechanism underlying fragmented sleep and memory deficits in 16p11.2 deletion mouse model of autism

Sleep disturbances are prevalent in children with autism spectrum disorder (ASD) and have a major impact on the quality of life. Strikingly, sleep problems are positively correlated with the severity of ASD symptoms, such as memory impairment. However, the neural mechanisms underlying sleep disturbances and cognitive deficits in ASD are largely unexplored. Here, we show that non-rapid eye movement sleep (NREMs) is highly fragmented in the 16p11.2 deletion mouse model of ASD. The degree of sleep fragmentation is reflected in an increased number of calcium transients in the activity of locus coeruleus noradrenergic (LC-NE) neurons during NREMs. Exposure to a novel environment further exacerbates sleep disturbances in 16p11.2 deletion mice by fragmenting NREMs and decreasing rapid eye movement sleep (REMs). In contrast, optogenetic inhibition of LC-NE neurons and pharmacological blockade of noradrenergic transmission using clonidine reverse sleep fragmentation. Furthermore, inhibiting LC-NE neurons restores memory. Rabies-mediated unbiased screening of presynaptic neurons reveals altered connectivity of LC-NE neurons with sleep- and memory regulatory brain regions in 16p11.2 deletion mice. Our findings demonstrate that heightened activity of LC-NE neurons and altered brain-wide connectivity underlies sleep fragmentation in 16p11.2 deletion mice and identify a crucial role of the LC-NE system in regulating sleep stability and memory in ASD.

Sleep: How stress keeps you up at night

Stress disrupts sleep, but the neural mechanisms underlying this relationship remain unclear. Novel findings in mice reveal a hypothalamic circuit that fragments sleep and promotes arousal after stress.