NREM Sleep Duration Research Articles

Sleep disturbance correlated with severity of neuropathic pain in sciatic nerve crush injury model.

The association between sleep and pain has been investigated widely. However, inconsistent results from animal studies compared with human data show the need for a validated animal model in the sleep-pain association field. Our study aims to validate common neuropathic pain models as a tool for evaluating the sleep-pain association. Electrodes electroencephalogram (EEG) and electromyogram (EMG) were surgically implanted to measure sleep. The von Frey test was used to measure pain sensitivity. Following the baseline data acquisition, two pain-modelling procedures were performed: sciatic nerve crush injury (SCI) and common peroneal nerve ligation (CPL). Post-injury measurements were performed on days 1, 5, 10, and 15 post-surgery. The results presented decreased paw withdrawal thresholds and reduced NREM sleep duration in both models on the first post-surgery day. In the SCI model, NREM sleep duration was negatively correlated with paw withdrawal thresholds (p = 0.0466), but not in the CPL model. Wake alpha and theta EEG powers were also correlated with the pain threshold. The results confirm that the SCI model shows disturbed sleep patterns associated with increased pain sensitivity, suggesting it is a reliable tool for investigating sleep disturbances associated with neuropathic pain.

Ultradian sleep cycles: Frequency, duration, and associations with individual and environmental factors—A retrospective study

ObjectiveSleep varies between individuals in response to sleep-wake history and various environmental factors, including light and noise. Here we report on the intranight variation of the ultradian nonrapid eye movement-rapid eye movement (NREM-REM) sleep cycle in 369 participants who have contributed to different laboratory studies from 1994 to 2020 at the Centre for Chronobiology, Basel, Switzerland. ResultsWe observed a large interindividual variability in sleep cycle duration, including NREM and REM sleep episodes in healthy participants who were given an 8-hour sleep opportunity at habitual bedtime in controlled laboratory settings. The median sleep cycle duration was 96 minutes out of 6064 polysomnographically-recorded cycles. The number and duration of cycles were not normally distributed, and the distribution became narrower for NREM sleep and wider for REM sleep later in the night. The first cycle was consistently shorter than subsequent cycles, and moderate presleep light or nocturnal noise exposure had no significant effects on ultradian sleep cycle duration. Age and sex significantly affected NREM and REM sleep duration, with older individuals having longer NREM and shorter REM sleep particularly in the end of the night, and females having longer NREM sleep episodes. High sleep pressure (ie, sleep deprivation) and low sleep pressure (ie, multiple naps) altered ultradian sleep cycles, with high sleep pressure leading to longer NREM sleep in the first cycle, and low sleep pressure leading to longer REM sleep episodes. Positive correlations were observed between N2 and NREM duration, and between N1 and REM duration. Weak intrasleep REM sleep homeostasis was also evident in our data set. ConclusionsWe conclude that ultradian sleep cycles are endogenous biological rhythms modulated by age, sex, and sleep homeostasis, but not directly responsive to (moderate levels of) environmental cues in healthy good sleepers.

The effect of diet-induced obesity on sleep and breathing in female mice.

Obesity and male sex are main risk factors for sleep-disordered breathing (SDB). We have shown that male diet-induced obesity (DIO) mice develop hypoventilation, sleep apnea, and sleep fragmentation. The effects of DIO on breathing and sleep architecture in females have not been investigated. We hypothesized that female mice are less susceptible to the detrimental effects of DIO on sleep and SDB compared to males. Female DIO-C57BL/6J and lean C57BL/6J mice underwent 24-hour metabolic studies and were exposed to 8% CO2 to measure the hypercapnic ventilatory response (HCVR), and sleep studies. Ventilatory response to arousals was calculated as ratio of the average and peak minute ventilation (VE) during each arousal relative to the baseline VE. Breathing stability was measured with Poincaré plots of VE. Female obesity was associated with decreased metabolism, indicated by reduced oxygen consumption (VO2) and CO2 production (VCO2). VE in 8% CO2 and HCVR were significantly attenuated during wakefulness. NREM sleep duration was reduced in DIO mice, but REM sleep was preserved. Ventilation during NREM and REM sleep was augmented compared to lean mice. Arousal frequency was similar between groups. Obesity increased the frequency of spontaneous arousals, whereas the apnea index was 4-fold reduced in DIO compared to lean mice. Obesity decreased pre- and post-apnea arousals. Obese mice had more stable breathing with reduced ventilatory response to arousals, compared to lean females. We conclude that obese female mice are protected against SDB, which appears to be related to an attenuated CO2 responsiveness, compared to the lean state.

0261 Sleep Disturbance Reliably Predicted by Pain Sensitivity in Sciatic Nerve Crush Injury Model

Abstract Introduction A bi-directional relationship between sleep and neuropathic pain is of interest because of its impact on human health. Numerous studies in humans and animals have examined the association between sleep and neuropathic pain. However, animal studies showed inconsistent results compared to human data. Therefore, validation of an animal model for sleep-pain association research is needed. We examined the animal models to identify a best-fit model predicting sleep disturbances with the level of neuropathic pain. Methods Adult male C57BL/6J mice (n=7 per group) were implanted with electrodes for electroencephalogram (EEG) and electromyogram. After two weeks of recovery, we obtained baseline EEG data for 24 hours and evaluated the paw withdrawal threshold, a measure of pain sensitivity, by the von Frey test. Afterward, sciatic nerve crush injury (SCI) and common peroneal nerve ligation (CPL) were conducted to make the two different neuropathic pain models. Post-surgery sleep was recorded continuously for 24 hours, followed by von Frey tests. EEG recording during the light period and von Frey tests were repeated on post-surgery days 5, 10, and 15. Results Both SCI and CPL models showed lower paw withdrawal thresholds after the peripheral nerve injury. NREM sleep duration on post-surgery day 1 was reduced significantly compared to baseline in both SCI and CPL, but only SCI showed decreased REM sleep. There was a significant positive correlation between paw withdrawal threshold and NREM sleep duration in SCI (P< 0.0001) but not CPL. Also, wake alpha and theta EEG powers were correlated with pain threshold. Conclusion We confirmed that both models of neuropathic pain disturbed sleep patterns. Nevertheless, sleep disturbances were reliably predicted by the pain sensitivity in the SCI model. Hence, we suggest SCI as a reliable pain model for studying the mechanism of sleep-pain association. Support (if any)

0255 Female Mice Are Less Susceptible to the Effects of Diet-Induced Obesity on Sleep and Sleep-Disordered Breathing

Abstract Introduction Diet-induced obesity (DIO) in male mice is a well-established model of sleep-disordered breathing (SDB). Male DIO mice manifest hypoventilation, increased apnea severity, and sleep fragmentation. The effects of DIO on breathing during sleep and sleep architecture in females have been insufficiently investigated. We hypothesized that female mice are less susceptible to the detrimental effects of DIO on sleep and SDB compared to males. Methods Full-polysomnographies were performed in 15 lean female C57BL/6J and 14 female DIO-C57BL/6J mice using a whole-body plethysmography chamber. Ventilatory response to an arousal was calculated as ratio of the average minute ventilation (VE) during each arousal (2.5s) relative to the baseline VE. Breathing stability was measured using Poincaré plots of VE. Mice were exposed to 8% CO2 to measure the hypercapnic ventilatory response (HCVR). Mice underwent 24-h metabolic studies. Results Obesity was associated with hypometabolism, indicated by reduced oxygen consumption (VO2) and CO2 production in DIO mice. VE in 8% CO2 and HCVR were significantly suppressed suggesting a decreased CO2 sensitivity in obese animals. NREM sleep duration was reduced, but REM sleep was preserved. Arousal frequency and VE during NREM and REM sleep were similar between groups. However, apnea severity was 4-fold augmented in lean females compared to DIO mice (14.7±3.9 vs 74.2±11.9 events/h; P< 0.001). In lean mice, the increased frequency of apneas was mainly attributed to sleep fragmentation since the events were predominantly post-arousals. Breathing stability during sleep was significantly increased in lean mice. Ventilatory response to an arousal was 30% increased in lean females compared to DIO group. Conclusion Our results suggest potential sex differences in the effects of DIO on breathing during sleep and sleep architecture. DIO in females appears to be less detrimental regarding SDB severity. The mechanisms underlying the augmented SDB severity in lean females are unknown, but an exacerbated CO2 responsiveness during sleep related to sleep fragmentation could play an important role. Support (if any) American Heart Association Postdoctoral Fellowship Award 828142, NHLBI grant NIH R01s HL128970, HL133100, and HL13892, American Academy of Sleep Medicine Foundation 238-BS-20, and American Thoracic Society Unrestricted Award.

Progressive sleep disturbance in various transgenic mouse models of Alzheimer's disease.

Alzheimer's disease (AD) is the leading cause of dementia. The relationship between AD and sleep dysfunction has received increased attention over the past decade. The use of genetically engineered mouse models with enhanced production of amyloid beta (Aβ) or hyperphosphorylated tau has played a critical role in the understanding of the pathophysiology of AD. However, their revelations regarding the progression of sleep impairment in AD have been highly dependent on the mouse model used and the specific techniques employed to examine sleep. Here, we discuss the sleep disturbances and general pathology of 15 mouse models of AD. Sleep disturbances covered in this review include changes to NREM and REM sleep duration, bout lengths, bout counts and power spectra. Our aim is to describe in detail the severity and chronology of sleep disturbances within individual mouse models of AD, as well as reveal broader trends of sleep deterioration that are shared among most models. This review also explores a variety of potential mechanisms relating Aβ accumulation and tau neurofibrillary tangles to the progressive deterioration of sleep observed in AD. Lastly, this review offers perspective on how study design might impact our current understanding of sleep disturbances in AD and provides strategies for future research.

Female Mice Are Less Susceptible to the Effects of Diet-Induced Obesity on Sleep and Sleep-Disordered Breathing

Diet-induced obesity (DIO) in male mice is a well-established model of sleep-disordered breathing (SDB). Male DIO mice manifest obesity hypoventilation, increased apnea severity, and sleep fragmentation. The effects of DIO on breathing during sleep and sleep architecture in females have been insufficiently investigated. In this study, we aimed to compare the breathing and sleep patterns of lean and obese female mice of similar genetic background. We hypothesized that female mice are less susceptible to the detrimental effects of DIO on sleep and SDB compared to males. Full-polysomnographies were performed in 15 lean female C57BL/6J and 14 female DIO-C57BL/6J mice using a whole-body plethysmography chamber. Arousals from sleep and apneas were manually scored. Ventilatory response to an arousal was calculated as ratio of the peak minute ventilation (V E ) during each arousal relative to the baseline V E (from 2.5s to 5s preceding the arousal). Breathing stability was measured using Poincaré plots of V E . Mice were acutely exposed to 8% CO 2 to measure the hypercapnic ventilatory response (HCVR). An additional 10 mice (5 each/group) underwent 24-h metabolic studies. We found that obesity was associated with hypometabolism, indicated by reduced oxygen consumption (VO 2 ) and CO 2 production in DIO mice. VE in 8% CO 2 and HCVR were significantly suppressed suggesting a decreased CO 2 sensitivity in obese animals. NREM sleep duration was reduced, but REM sleep was preserved. Arousal frequency was similar between groups (~78 events/h). DIO mice hypoventilated during NREM sleep. However, apnea severity was 4-fold augmented in lean females compared to DIO mice (14.7±3.9 vs 74.2±11.9 events/h; P<0.001). Breathing stability during sleep was significantly increased in lean mice. Ventilatory response to an arousal was higher in lean females, but it was attributed to an overall increased V E during arousal and at baseline. Our results suggest potential sex differences in the effects of DIO on breathing during sleep and sleep architecture. DIO in females appears to be less detrimental regarding SDB severity. The mechanisms underlying the augmented SDB severity in lean females are unknown, but an exacerbated CO2 responsiveness during sleep could play an important role. American Heart Association Postdoctoral Fellowship Award 828142 (to L.J.K.), NHLBI grant NIH R01 HL128970, R01 HL133100, and R01 HL13892 (to V.Y.P.), American Academy of Sleep Medicine Foundation 238-BS-20, and American Thoracic Society Unrestricted Award (to L.V.P.) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Blue Transparent OLEDs with High Stability and Transmittance for Modulating Sleep Disorders (Adv. Mater. Interfaces 11/2023)

Blue Transparent Organic Light-Emitting Diodes In article number 2202443, Kyung-Cheol Choi and co-workers develop high-transmittance and stable blue transparent organic light-emitting diodes (TrOLEDs) using optimized dielectric-metal-dielectric (DMD) electrodes with silver, seed, and capping layers. They also demonstrated the TrOLEDs on glasses for visual stimulus devices and proposed an animal experimental protocol for modulating NREM sleep duration with blue light stimulation. The proposed blue TrOLEDs could be a practical and convenient solution for modulating sleep disorders in a wearable form factor.

Correlations between sleep architecture and sleep-related masseter muscle activity in children with sleep bruxism.

Sleep bruxism (SB) occurring during No-REM (nREM) sleep and increase in microarousals per hour have been described in adults, but not in children. To assess the correlation between sleep architecture and masseter muscle activity related to sleep bruxism (SB/MMA) in children. Forty-three children aged 7-12 years (mean age: 9.4 ± 1.3) with confirmed SB underwent a two-night polysomnographic (PSG) study in a sleep laboratory, for accommodation (first night) and data collection (second night). Data on sleep architecture (total sleep duration (TSD), sleep efficiency (SE), sleep onset latency (SOL), REM and nREM sleep duration and proportion and microarousals/hour during REM and nREM sleep) and episodes/hour of SB/MMA were recorded. Single and multiple-variable linear regression analyses were performed to assess the correlation between data on sleep architecture (predictors) and SB/MMA (dependent variable). Shorter TSD, REM and nREM stage 1 sleep duration,longerSOLand more microarousals/hour during REM and nREM sleep were found to be positive predictors of SB/MMA in children in the multiple-variable regression analysis (R2 =0.511). Within the limitations of this study, it can be concluded that SB/MMA is correlated with altered sleep architecture in children (shorter total sleep duration (TSD), shorter nREM and REM sleep and higher microarousals during REM and nREM sleep). Nevertheless, the clinical significance of these findings need to be demonstrated in future studies.

Early life sleep disruption has long lasting, sex specific effects on later development of sleep in prairie voles

In mammals, sleep duration is highest in the early postnatal period of life and is critical for shaping neural circuits that control the development of complex behaviors. The prairie vole is a wild, highly social rodent that serves as a unique model for the study of complex, species-typical social behaviors. Previous work in our laboratory has found that early life sleep disruption (ELSD) in prairie voles during a sensitive window of postnatal development leads to long lasting changes in social and cognitive behaviors as well as structural changes in excitatory and inhibitory neural circuits in the brain. However, it is currently unknown how later sleep is impacted by ELSD, both shortly after ELSD and over the long term. Therefore, the aim of this study was to describe the effects of ELSD on later life sleep, compared to sleep in normally developing prairie voles. First, we conducted tethered electroencephalogram/electromyogram (EEG/EMG) recordings in juvenile prairie voles undergoing ELSD, compared to Control conditions. Second, we conducted 24 h of home cage tethered EEG/EMG recordings in either adolescent or adult male and female prairie voles that had previously undergone ELSD or Control conditions as juveniles. We found that, as adults, male ELSD prairie voles showed persistently lower REM sleep duration and female ELSD prairie voles showed persistently higher NREM sleep duration compared to Controls, but no other sleep parameters differed. We concluded that 1) persistent effects of ELSD on sleep into adulthood may contribute to the social and cognitive deficits observed in adult voles, and 2) sleep disruption early in life can influence later sleep patterns in adulthood.

0192 Effects of emerging alcohol use on developmental trajectories of functional sleep measures in adolescents

Abstract Introduction Adolescence is characterized by developmental changes in sleep timing and architecture as well as alcohol use initiation. While the effects of acute and chronic alcohol use on sleep in adults are well-documented, much less is known in adolescents. We used longitudinal data from the National Consortium on Alcohol and Neurodevelopment in Adolescence (NCANDA) to examine how emerging alcohol use affected sleep architecture in adolescents. Methods Overnight polysomnographic recordings were made each year, for 4 years, in 94 adolescents (12–21 years at baseline, 43% female) from the NCANDA cohort. All participants were no or low (youth adjusted Cahalan score of zero) alcohol users at baseline. These data were used to examine developmental trajectories of sleep macro-architecture and sleep electroencephalographic (EEG) measures using linear mixed effect models (LMMs), considering age, sex, family history of alcohol use, body mass index, ethnicity, and alcohol use class (i.e., no-to-low, moderate or heavy) at each annual assessment. Results There were strong developmental changes in sleep macro-structure and EEG, most notably, a decrease in slow wave sleep percentage and slow wave (delta) EEG activity with advancing age (p=0.02)​. Compared to those who remained no-to-low drinkers, participants who became moderate/heavy drinkers during the follow-up period, had different sleep trajectories, especially those older at baseline at baseline, including higher slow wave activity (p = 0.04), higher REM sleep percentage (p = 0.03), poorer sleep efficiency​ (p=0.003), and longer latency to sustained sleep (p = 0.03). The effects of alcohol use depended on sex, with male heavy drinkers having more REM sleep than female heavy drinkers (p = 0.04). Overall, a positive family history of alcohol use was associated with less NREM sleep and shorter sleep duration. Conclusion Our results present novel findings showing that emerging alcohol use during adolescence exerts complex effects on sleep macro- and micro-structure, over and above normal developmental changes in sleep. These effects could, in part, be alcohol effects on brain maturation processes underlying sleep regulation. Support (If Any) AA021696, AA021690

Role of medullary cardiorespiratory neurons on the maintenance of altered sleep function in heart failure

Sleep‐disordered breathing (SDB) and sleep fragmentation (SF) (i.e. repetitive short interruptions of sleep) are frequently reported in heart failure (HF) patients. Interestingly, SDB and SF has been both closely associated with the generation of breathing disorders. Importantly, our previous work showed that partial ablation of pre‐sympathetic catecholaminergic neurons (C1) located at the rostral ventrolateral medulla (RVLM) results in marked improvements in breathing disorders in rats with HF. However, the contribution of RVLM‐C1 neurons on sleep‐related disorders in the setting of cardiac failure has not been previously studied. Therefore, we aimed to determine the contribution of RVLM‐C1 neurons on sleep architecture in HF. Adult male Sprague‐Dawley rats (250 g) underwent volume overload to induce HF. After four weeks, anti‐dopamine β‐hydroxylase‐saporin (DβH–SAP: 2.5ng/150nl; or saline) was used to selectively destroy RVLM‐C1 neurons (‐12.36 mm AP from bregma; ± 2.2 mm ML; 8.5 mm DV). Breathing function was determined by unrestrained whole‐body plethysmograph and sleep function/sleep stages were assessed in electroencephalogram and electromyogram recordings obtained for chronic implanted leads. Compared to Sham rats, HF animals displayed no differences in the total time spent in rapid eye movement (REM) and non‐rapid eye movement (nREM) sleep stages. However, duration of each nREM epoch was significantly (p<0.05) lower in HF rats (3.4 ± 0.3 vs. 2.2 ± 0.2 min, Sham vs. HF, respectively). Accordingly, HF rats showed an increased number of nREM epochs compared to Sham animals (12.0 ± 2 vs. 17 ± 2 events/h, Sham vs. HF, respectively). Interestingly, HF rats displayed loss of ventilatory stability compared to Sham rats only at nREM sleep (Irregularity score, nREM: 12.1 ± 2.0 vs. 15.9 ± 1.8%; REM: 22.9 ± 2.0 vs 24.1 ± 3.2%; Sham vs. HF, respectively). Furthermore, the incidence of sigh‐triggered arousal events during nREM sleep was increased in HF rats. Conversely, sleep probability was decreased by ~35% in HF animals compared to Sham animals. Remarkably, ablation of RVLM‐C1 neurons with DβH–SAP in HF improved nREM breathing regularity and restores normal nREM sleep duration (3.4 ± 0.3 vs. 3.1 ± 0.3 min, Sham vs. HF+DβH–SAP, respectively). In addition, DβH–SAP treatment in HF decreased sigh‐triggered arousals by ~45% being the outcome a reduction in SF in HF rats that underwent C1 ablation. Our data shows that irregular breathing is closely linked to altered sleep in HF rats and support a role for RVLM‐C1 neurons on sleep regulation in the setting of HF.

Microglia modulate hippocampal synaptic transmission and sleep duration along the light/dark cycle.

Microglia, the brain's resident macrophages, actively contribute to the homeostasis of cerebral parenchyma by sensing neuronal activity and supporting synaptic remodeling and plasticity. While several studies demonstrated different roles for astrocytes in sleep, the contribution of microglia in the regulation of sleep/wake cycle and in the modulation of synaptic activity in the different day phases has not been deeply investigated. Using light as a zeitgeber cue, we studied the effects of microglial depletion with the colony stimulating factor‐1 receptor antagonist PLX5622 on the sleep/wake cycle and on hippocampal synaptic transmission in male mice. Our data demonstrate that almost complete microglial depletion increases the duration of NREM sleep and reduces the hippocampal excitatory neurotransmission. The fractalkine receptor CX3CR1 plays a relevant role in these effects, because cx3cr1 GFP/GFP mice recapitulate what found in PLX5622‐treated mice. Furthermore, during the light phase, microglia express lower levels of cx3cr1 and a reduction of cx3cr1 expression is also observed when cultured microglial cells are stimulated by ATP, a purinergic molecule released during sleep. Our findings suggest that microglia participate in the regulation of sleep, adapting their cx3cr1 expression in response to the light/dark phase, and modulating synaptic activity in a phase‐dependent manner.

Optogenetic sleep enhancement improves fear-associated memory processing following trauma exposure in rats

Sleep disturbances are commonly found in trauma-exposed populations. Additionally, trauma exposure results in fear-associated memory impairments. Given the interactions of sleep with learning and memory, we hypothesized that increasing sleep duration following trauma exposure would restore overall function and improve trauma-induced fear-associated memory dysfunction. Here, we utilized single prolonged stress, a validated rodent model of post-traumatic stress disorder, in combination with optogenetic activation of hypothalamic melanin-concentrating hormone containing cells to increase sleep duration. The goal of this work was to ascertain if post-trauma sleep increases are sufficient to improve fear-associated memory function. In our laboratory, optogenetic stimulation after trauma exposure was sufficient to increase REM sleep duration during both the Light and Dark Phase, whereas NREM sleep duration was only increased during the Dark Phase of the circadian day. Interestingly though, animals that received optogenetic stimulation showed significantly improved fear-associated memory processing compared to non-stimulated controls. These results suggest that sleep therapeutics immediately following trauma exposure may be beneficial and that post-trauma sleep needs to be further examined in the context of the development of post-traumatic stress disorder.

Determinants of the changes in positive airway pressure for the retitration in patients with obstructive sleep apnea syndrome

During long-term follow-up of the patients with obstructive sleep apnea syndrome (OSAS) under the positive airway pressure (PAP) therapy, it waits to be explored whether or when routine retitrations are indicated. We prospectively followed up 133 patients for 10 years to define which demographical or polysomnographic factors should be taken into account to determine the need for retitration. Patients were retitrated at 1st, 2nd, 5th, and 10th follow-up years. A change in pressures ≥ 2cmH2O was present in more than half of the patients at 2nd and 5th years. Changes in weight for at least 10 kg showed a significant correlation with the changes in pressures ≥ 2cmH2O (p = 0.023) and ≥ 3cmH2O (p = 0.047) at 2nd year. OSAS-related complaints, nasal or upper airway surgery, or emergence of cardiovascular diseases were not correlated with the changes in pressures. Apnea–hypopnea index (AHI) at diagnostic night was positively correlated with the changes in pressures ≥ 3cmH2O at 1st and 5th years. The percentage of N3 sleep at first titration night showed positive correlation with changes in pressures ≥ 3cmH2O at 2nd and 5th years. The index of periodic leg movements in sleep (PLMS) and PLMS-arousal index at first titration night was positively correlated with any change in pressures at 2nd and 5th years. Our findings showed that vast changes in weight, high AHI at diagnostic night, increased duration of deep NREM sleep and high PLMS and PLMS-arousal indices at first titration night should be noted as important indicators for retitration within the first 5 years of follow-up.

0327 NREM Sleep EEG in Typically Developing and Drug-Naïve ADHD Adolescents: Data from a Longitudinal Study

Abstract Introduction Structural MRI studies suggest delayed brain maturation in children with attention deficit hyperactivity disorder (ADHD). The steep adolescent decline in sleep slow wave EEG activity provides an opportunity to investigate brain electrophysiological evidence for this maturational delay. Most ADHD sleep EEG studies have been cross-sectional. Here we present data from an ongoing longitudinal study of the maturational trajectories of sleep EEG in drug-naïve ADHD and typically developing adolescents. Methods Nine children diagnosed with ADHD (combined subtype, DSM-V criteria, mean age 12.39±0.61 years), and nine typically developing controls (12.07±0.35 years) were recruited. Subjects underwent an adaptation night and all night polysomnography twice yearly at the Laboratory. Sleep EEG was analyzed using fast Fourier transform. NREM delta and theta EEG activity were compared across first two recordings. Results Group effects (ADHD vs. control) on all night delta and theta energy, and delta power were not significant (p>0.2 for all). All night theta power was lower (p=0.035) for the ADHD group, and all night NREM sleep duration trended (p=0.060) toward being lower for the ADHD group. Controlling for sleep duration differences by examining only the first 5 h of NREM sleep showed no group effect on delta power (p=0.77) and a trend toward lower theta power (p=0.057) for the ADHD group. Conclusion At age 12 to 13 years, NREM sleep delta EEG did not differ between ADHD and control subjects. Theta power, which declines at a younger age than delta, was lower in control subjects. The two recordings thus far differ only by 6 months. The entire study will provide 5 semiannual recordings and allow us to determine if the higher theta power in the ADHD group will hold and if delta power will be greater as well, and thus provide electrophysiological support for the delayed brain maturation suggested by MRI findings. Support Shota Rustaveli National Science Foundation Grant FR17_94; Subjects Recruitment Support - Mental Health Service in Tbilisi “Kamara”.

Differential modulation of NREM sleep regulation and EEG topography by chronic sleep restriction in mice

Compensatory elevation in NREM sleep EEG delta power has been typically observed following prolonged wakefulness and widely used as a sleep homeostasis indicator. However, recent evidence in human and rodent chronic sleep restriction (CSR) studies suggests that NREM delta power is not progressively increased despite of accumulated sleep loss over days. In addition, there has been little progress in understanding how sleep EEG in different brain regions responds to CSR. Using novel high-density EEG electrode arrays in the mouse model of CSR where mice underwent 18-h sleep deprivation per day for 5 consecutive days, we performed an extensive analysis of topographical NREM sleep EEG responses to the CSR condition, including period-amplitude analysis of individual slow waves. As previously reported in our analysis of REM sleep responses, we found different patterns of changes: (i) progressive decrease in NREM sleep duration and consolidation, (ii) persistent enhancement in NREM delta power especially in the frontal and parietal regions, and (iii) progressive increases in individual slow wave slope and frontal fast oscillation power. These results suggest that multiple sleep-wake regulatory systems exist in a brain region-specific manner, which can be modulated independently, especially in the CSR condition.

Oral Delivered Dexmedetomidine Promotes and Consolidates Non-rapid Eye Movement Sleep via Sleep-Wake Regulation Systems in Mice.

Dexmedetomidine, a highly selective α2-adrenergic agonist, is widely used in clinical anesthesia and ICU sedation. Recent studies have found that dexmedetomidine-induced sedation resembles the recovery sleep that follows sleep deprivation, but whether orally delivered dexmedetomidine can be a candidate for the treatment of insomnia remains unclear. In this study, we estimated the sedative effects of orally delivered dexmedetomidine by spontaneous locomotor activity (LMA), and then evaluated the hypnotic effects of dexmedetomidine on sleep–wake profiles during the dark and light phase using electroencephalography/electromyogram (EEG/EMG), respectively. Using c-Fos staining, we explored the effects of dexmedetomidine on the cerebral cortex and the sub-cortical sleep–wake regulation systems. The results showed that orally delivered dexmedetomidine at 2 h into the dark cycle reduced LMA and wakefulness in a dose-dependent manner, which was consistent with the increase in non-rapid eye movement sleep (NREM sleep). However, dexmedetomidine also induced a rebound in LMA, wake and rapid eye movement sleep (REM sleep) in the later stage. In addition, orally delivered dexmedetomidine 100 μg/kg at 2 h into the light cycle shortened the latency to NREM sleep and increased the duration of NREM sleep for 6 h, while decreased REM sleep for 6 h. Sleep architecture analysis showed that dexmedetomidine stabilized the sleep structure during the light phase by decreasing sleep–wake transition and increasing long-term NREM sleep (durations of 1024–2024 s and >2024 s) while reducing short-term wakefulness (duration of 4–16 s). Unlike the classic hypnotic diazepam, dexmedetomidine also increased the delta power in the EEG spectra of NREM sleep, especially at the frequency of 1.75–3.25 Hz, while ranges of 0.5–1.0 Hz were decreased. Immunohistochemical analysis showed that orally delivered dexmedetomidine 100 μg/kg at 2 h into the dark cycle decreased c-Fos expression in the cerebral cortex and sub-cortical arousal systems, while it increased c-Fos expression in the neurons of the ventrolateral preoptic nucleus. These results indicate that orally delivered dexmedetomidine can induce sedative and hypnotic effects by exciting the sleep-promoting nucleus and inhibiting the wake-promoting areas.

The Impairments of Ca2+-dependent Hyperpolarization Pathway Altered NREM Sleep Duration in Mice

The Impairments of Ca2+-dependent Hyperpolarization Pathway Altered NREM Sleep Duration in Mice

0129 LOCAL THALAMIC RETICULAR NUCLEUS INHIBITION OF T-TYPE CALCIUM CHANNELS REDUCES SLEEP SPINDLES IN MICE

Parvalbumin (PV)-containing GABAergic thalamic reticular neurons (TRN) express Cav3.3 T-type calcium channels that are thought to generate burst firing necessary for spindle generation. Cav3.3 is a risk gene for schizophrenia, where spindle abnormalities are present. The role of Cav3.3 in the control of sleep and spindles has been examined using global Cav3.3 knockout mice but not with acute, local pharmacological blockade. Therefore, here we examined the inhibitory effect of a selective T-type inhibitor, TTA-P2, in TRN on sleep and spindles. In vitro recordings were made from identified TRN PV neurons in slices from mice (13-22d) expressing a red fluorescent protein in PV neurons. In vivo, mice (N=8) were implanted with bilateral microdialysis cannulae targeting TRN (AP -0.7, ML ±1.3, DV -4.0) and electrodes (EEG/EMG) for sleep-wake recordings. A custom Matlab script detected individual spindles (10-15Hz) in the EEG, allowing analysis of drug effects on spindle density (spindles/min) during NREM sleep. Data was compared with the ACSF-day values and related to the histological location of the probe. TRN-PV neurons exhibited low-threshold spikes/inward currents after removal of hyperpolarizing currents/voltage steps respectively, which were blocked by TTA-P2 (3 µM, n=4), confirming the expression of low threshold T-type Ca channels in TRN PV neurons. In 6/8 mice with probe locations in TRN (uni- or bi-lateral), TTA-P2 infusion at ZT2-6 significantly decreased (-27.0 ± 11.6%, p=0.008) spindle density (ACSF: 4.25 ± 0.19; TTA-P2: 3.13 ± 0.37) without any significant effect on amplitude or duration. There was no effect on NREM sleep duration, delta (0.5-4Hz) or slow-wave activity (0.5–1.5Hz). Localized pharmacological inhibition of T-type calcium channels within TRN selectively decreased NREM spindle density without an effect on NREM sleep. These results contrast with those observed with a constitutive, global knockout of Cav3.3, where sleep fragmentation was observed in addition to reduced spindles (Astori et al., 2011). Veterans Affairs Medical Research Service Awards, 5I01BX001356, I01BX001404, 1IK2BX002130, R21-NS079866, RO1-MH039683, PO1-HL095491, R21 NS093000, R03 MH107650, JTM received partial salary compensation and funding from Merck MISP, but has no conflict of interest with this work.