Stage N2 Sleep Research Articles

Neural oscillations after acute large artery atherosclerotic cerebral infarction during resting state and sleep spindles.

Electroencephalogram-microstate analysis was conducted using low-resolution electromagnetic tomography (LORETA)-KEY to evaluate dynamic brain network changes in patients with acute large artery atherosclerotic cerebral infarction (LAACI) during the rest and sleep stages. This study included 35 age- and sex-matched healthy controls and 34 patients with acute LAACI. Each participant performed a 3-h, 19-channel video electroencephalogram test. Subsequently, 20 epochs of 2-s sleep spindles during stage N2 sleep and five epochs of 10-s electroencephalogram data in the resting state for each participant were obtained. In both the resting state and sleep spindles, patients with LAACI displayed altered neural oscillations. The parameters of microstate A (coverage, occurrence, and duration) increased during the resting state in the patients with LAACI compared with healthy controls. The coverage and occurrence of microstate B and D were reduced in the LAACI group compared with the healthy controls (p < 0.05). Moreover, during sleep spindles, the duration of microstate A and the transition probability from microstate A and B to C decreased, but the coverage of microstate B and the transition rate from microstate B to D increased (p < 0.05) in the LAACI group compared with the healthy controls. These results enable better understanding of how neural oscillations are modified in patients with LAACI during the resting state and sleep spindles. Following LAACI, the dynamic brain network undergoes changes during sleep spindles and the resting state. Continued long-term investigations are required to determine how well these changes in brain dynamics reflect the clinical characteristics of patients with LAACI.

Effects of dexmedetomidine on postoperative sleep quality: a systematic review and meta-analysis of randomized controlled trials

Study objectivesTo assess the effect of dexmedetomidine (DEX) on postoperative sleep quality using polysomnography (PSG) to identify possible interventions for postoperative sleep disturbances.MethodsAn electronic search of PubMed/MEDLINE, EMBASE, Cochrane Library and Web of Science was conducted from database inception to November 20, 2022. Randomized controlled trials (RCTs) on the effect of DEX administration on postoperative sleep quality using PSG or its derivatives were included. No language restrictions were applied. The sleep efficiency index (SEI), arousal index (AI), percentages of stage N1, N2 and N3 of non-rapid eye movement (NREM) sleep, and rapid eye movement (REM) sleep were measured in our meta-analysis.ResultsFive studies, involving 381 participants were included. Administration of DEX significantly improved SEI, lowered AI, decreased the duration of stage N1 sleep and increased the duration of stage N2 sleep compared to placebo groups. There were no significant differences in the duration of stage N3 sleep and REM sleep. DEX administration lowered the postoperative Visual Analogue Scale (VAS) score and improved the Ramsay sedation score with no adverse effect on postoperative delirium (POD). However, high heterogeneity was observed in most of the primary and secondary outcomes.ConclusionsOur study provides support for the perioperative administration of DEX to improve postoperative sleep quality. The optimal dosage and overall effect of DEX on postoperative sleep quality require further investigation using large-scale randomized controlled trials.

Cardiorespiratory changes associated with micro-arousals during naps

The autonomic nervous system (ANS) and the central nervous system (CNS) interplay during sleep, particularly during phasic events such as micro-arousals, has been the subject of several studies. The underlying mechanisms of such relationship which remain unclear, specifically during daytime sleep, were partly investigated in this study. Napping polysomnography was performed on two occasions at least one week apart in 15 healthy subjects. The following cardiorespiratory variables were extracted from the recordings: tachogram, pulse transit time (PTT), pulse wave amplitude, respiratory cycle amplitude, and frequency. Two experts first detected micro-arousal events, then, cardiorespiratory variables were averaged by 30-s epochs over 2 min centered on the onset of the micro-arousals. We found that in the 30 s preceding the arousal events as detected on the electroencephalogram (EEG) recordings, there was a decrease in tachogram, pulse wave amplitude, and PTT values while the respiratory amplitude increased. These changes were more prominent in stage N2 and N3 sleep than in stage N1. The present findings provide new insights into the autonomic changes during the pre-arousal period in daytime naps, as all the variables investigated suggest a sympathetic physiological origin for the changes.

Motor neuron involvement threatens survival in spinocerebellar ataxia type 1.

Motor neuron involvement threatens survival in spinocerebellar ataxia type 1.

Effect of occlusal equilibration on masticatory muscle activity in females with sleep bruxism: a double-blind randomised controlled trial.

Masticatory muscle activity during sleep has been considered independent of variations in the structural characteristics of the dental occlusion. However, scientific evidence contradicting an occlusal causal role is missing. The purpose of this study was to test the null hypothesis that sleep bruxism (SB) is independent of the presence of occlusal interferences. A total of 17 healthy female subjects (mean [SD] age 24.9[4.1]years) presenting with SB, and randomly divided into two groups, were evaluated after receiving either elimination of occlusal interferences (Test group) or elimination of sharp margins without change in occlusal contacts (Control group). Audio-video polysomnography (PSG) recordings were undertaken before and after treatment (mean [SD] duration 14.4[3.8]months). Two subjects in each group (< 2 rhythmic masticatory muscle activity [RMMA]/h) were excluded for statistical analysis. During the total sleep time (TST), the Test group exhibited a higher reduction in frequency of episodes per hour than the Control group (p < 0.05). The reduction in duration of episodes was also higher in the Test group during the TST. The Test group presented an increase in sleep stage N3 (p < 0.05) at the final PSG when compared with the initial PSG, and a higher percentage of N3 (p < 0.05) at the final PSG when compared to the Control group. Elimination of occlusal interferences resulted in a significant reduction of masseter and temporal muscle activity during sleep in females presenting with SB. Based on these results, the null hypothesis is rejected. The hypothesis of occlusal interferences as a risk factor for SB is still patent.

Insomnia Severity is Associated with Morning Cortisol and Psychological Health.

Studies suggest associations between cortisol and sleep, and cortisol shows a profound diurnal rhythm. The evidence about the relationship between chronic insomnia and cortisol is mixed. Chronic insomnia is associated with the risk of mental health disorders. The aim of this study was to evaluate the association of insomnia severity and objective sleep pattern with morning cortisol level and psychological health. The instruments used were the Insomnia Severity Index (ISI), polysomnography, Beck Depression Inventory (BDI), and Profile of Mood States (POMS). Serum cortisol was analyzed by chemiluminescence. The data revealed significant positive correlations of ISI with morning cortisol level (r = 0.37, p = 0.03), BDI score (r = 0.44, p < 0.01), and POMS-tension anxiety (r = 0.39, p = 0.02). Sleep stages N2 and N3 were correlated with POMS-fatigue (r = 0.46, p < 0.01; r = -0.37, p = 0.04). Sleep stage N3 was also negatively correlated with POMS-tension-anxiety (r = -0.36, p = 0.04). Higher insomnia severity was associated with higher morning cortisol, depression, and tension-anxiety. Sleep stage N2 was associated with higher fatigue and N3 was associated with lower tension-anxiety and fatigue.

Maxillomandibular Advancement for OSA: A 25-year perspective

The aim of this study was to evaluate the result of maxillomandibular advancement (MMA) for the treatment of obstructive sleep apnea (OSA) by a single surgeon. Patients that underwent MMA for the treatment of OSA over a 25-year period were included in the study. Patients who initially presented for revision MMA surgery were excluded. Demographics (e.g., age, gender, pre- and post-MMA body mass index [BMI]), pre- and post-MMA cephalometrics (e.g., sella-nasion-point A angle [SNA], sella-nasion-point B angle [SNB], posterior airway space base of tongue [PAS]) and pre- and post-MMA sleep study metrics (e.g., respiratory disturbance index [RDI], lowest desaturation [SpO2-nadir], oxygen desaturation index [ODI], total sleep time [TST],% TST Stage N3 sleep,% TST rapid eye movement [REM] sleep) were abstracted. MMA surgical success was defined as a ≥ 50% reduction in RDI (or ODI) and post-MMA RDI (or ODI) < 20 events/hour. MMA surgical cure was defined as a post-MMA RDI (or ODI) < 5 events/hour. A total of 1010 patients underwent MMA for the treatment of OSA. The mean age was 39.6 ± 14.3 years, and the majority were male (77%). Nine hundred forty-one patients with complete pre- and postoperative PSG data were analyzed. The mean ODI and RDI improved from 32.6 ± 27.4 to 7.7 ± 15.5 and 39.1 ± 24.2 to 13.6 ± 14.6 events per hour, respectively. The overall surgical success and surgical cure based on ODI was 79.4% and 71.9%, respectively. The overall surgical success and surgical cure based on RDI was 73.1% and 20.7%, respectively. Stratified by preoperative RDI showed older age, greater BMI were associated with greater preoperative RDI. Bivariate predictors of greater RDI reduction include younger age, female gender, lower preoperative BMI, higher preoperative RDI, greater BMI reduction postoperatively and greater change in SNA and PAS. Bivariate predictors of surgical cure based on RDI (RDI < 5) include younger age, female gender, lower preoperative RDI, and greater change in SNA and PAS. Bivariate predictor of RDI success (RDI < 20) include younger age, female gender, lower preoperative BMI, lower preoperative RDI, greater BMI reduction, greater increase in SNA, SNB and PAS postoperatively. Comparison of the first 500 patients and the later 510 patients demonstrate patients undergoing MMA have become younger, having lower RDI while achieving a better surgical outcome. Linear multivariate associations of greater percentage RDI reduction include younger age, greater percent change of SNA, greater preoperative SNA, lower preoperative BMI and higher preoperative RDI. MMA is an effective treatment to improve OSA, but the result can vary. Patient selection based on favorable prognostic factors and maximizing the advancement distance can improve outcomes.

Abstract MP48: Cross-Sectional and Prospective Associations Between Slow-Wave Sleep and Type 2 Diabetes: The Multi-Ethnic Study of Atherosclerosis

Introduction: Slow-wave sleep (also known as stage N3 sleep), a marker of deep restorative sleep, is implicated in the regulation of insulin resistance and glucose homeostasis and may impact cardiometabolic health. Hypothesis: We conducted both cross-sectional and prospective analyses to test the hypothesis that higher proportion and longer duration of N3 sleep are associated with reduced diabetes risk in older adults. Methods: A sub-sample of participants from the Multi-Ethnic Study of Atherosclerosis completed one-night polysomnography at Exam 5 (2010-2013) and were prospectively followed until Exam 6 (2016-2018). Continuous measures of N3 proportion (%) and duration (minutes) and their corresponding quartiles were used as primary exposures. Diabetes status was assessed in both Exams and was defined as fasting blood glucose≥126 mg/dl, HbA1c≥6.5%, antidiabetic medications use, or self-reported doctor diagnosis of diabetes. We used Modified Poisson regression to examine the cross-sectional associations of N3 proportion and duration with prevalent diabetes in Exam 5. Cox proportional hazards models were used to estimate risk of incident diabetes according to N3 measures. We sequentially adjusted for sociodemographic factors, lifestyles, adiposity measures, and multiple sleep-related factors, such as average sleep duration, apnea-hypopnea index, and insomnia symptoms. Results: In cross-sectional analyses (N=2,026, mean age: 69 years), diabetes prevalence was 28% (n=572). Compared to participants in the first quartile of N3 proportion (&lt;2.0%), participants in the fourth quartile (≥15.4%) were 29% less likely to have prevalent diabetes (Prevalence ratio: 0.71; 95% CI: 0.58,0.87; P -trend: 0.0016]. The association was attenuated and not significant after adjusting for confounders, particularly BMI. In prospective analyses (N=1,251), there were 129 incident diabetes cases over 6,346 person-years of follow-up (mean follow-up time: 5.1 years). A curvilinear relationship was observed between N3 proportion and incident diabetes risk. The hazard ratio (95% CI) of developing diabetes versus the lowest quartile was 0.45 (0.25,0.81) for quartile 2, 0.31 (0.14,0.70) for quartile 3, and 0.30 (0.10,0.90) for quartile 4 ( P -nonlinearity=0.0169, based on restricted cubic spline model). The association remained significant in the fully adjusted model ( P -nonlinearity=0.0319). The results were similar for N3 duration. Conclusions: Higher N3 proportion and longer N3 duration were prospectively associated with lower diabetes risk in a nonlinear fashion among older American adults.

Clinical phenotype of obstructive sleep apnea in older adults: a hospital-based retrospective study in China.

The prevalence of obstructive sleep apnea (OSA) in older people (aged over 65years) is high. However, OSA in older populations has not received sufficient attention. This study examined the clinical phenotypic characteristics of older patients with newly diagnosed OSA. A total of 110 older patients (≥ 65years) and 220 younger patients (< 65years), matched by gender, body mass index (BMI), and apnea-hypopnea index (AHI), were enrolled in this retrospective study. Clinical manifestations, comorbidities, and polysomnographic results were compared between the two groups, and correlations between age ≥ 65years and OSA comorbidities were explored. Nocturia was more common in older patients with OSA, as with lower sleep efficiency, longer wake after sleep onset, increased stage N1 sleep, and decreased stage N3 sleep and average SpO2. The proportions of older OSA patients who had comorbid hypertension, coronary artery disease (CAD), chronic obstructive pulmonary disease, and ischemic stroke were significantly higher than those of younger patients. The incidence of tonsillar enlargement and pharyngeal narrowing was lower in older patients. Age ≥ 65years was an independent risk factor for patients with OSA to have hypertension (OR: 1.89, 95% CI: 1.11-3.21), CAD (OR: 4.83, 95% CI: 2.29-10.21), and ischemic stroke (OR: 2.92, 95% CI: 1.02 to 8.38). The presence of OSA in older adults was associated with significant abnormalities of sleep architecture, aggravated nocturnal hypoxia and increased risks of hypertension, CAD, and stroke, which can be distinguished as a unique clinical phenotype.

Childhood absence epilepsy patients with cognitive impairment have decreased sleep spindle density

ObjectiveTo explore the differences in sleep spindle (SS) characteristics during stage N2 sleep between children with childhood absence epilepsy and healthy controls, and between children with childhood absence epilepsy with or without cognitive impairment. MethodsWe recruited 29 children (14 females, 15 males, mean age: 8 (2.5) years) with childhood absence epilepsy who did not undergone antiseizure treatments previously and 30 age-matched controls (14 females, 16 males, mean age: 9 (3.0) years). For all patients, data on medical history were collected. Each child was monitored overnight by long-term video electroencephalography and was evaluated by the Wechsler Intelligence Scale for Children-Fourth Edition. Next, we compared anterior SS characteristics, including density, frequency, cycle length, duration, amplitude, and percentage of sleep stages. ResultsThe childhood absence epilepsy group exhibited lower spindle density and duration in the first 37.5 min of stage N2 sleep than the control group (P < 0.01). A decrease in spindle density could be observed in the childhood absence epilepsy group with aggravated cognition impairment. The spindle density was substantially lower in the cognitively impaired group than in the cognitively unimpaired group (P < 0.01). No significant differences were observed in SS amplitude, SS frequency, SS cycle length, and the distribution of sleep stages. ConclusionsReduction in spindle density and duration is associated with the mechanisms underlying childhood absence epilepsy. The deficit in SS density is related with impaired cognition. This deficiency in SSs may be a useful predictive indicator of cognitive impairment in children with absence epilepsy, indicating that SSs may become a useful biomarker and potential adjuvant anti-seizure target for cognitive impairment caused by childhood absence epilepsy.

Analysis of the effect of brexpiprazole on sleep architecture in patients with schizophrenia: A preliminary study.

Brexpiprazole is an atypical antipsychotic drug widely used in Japan for the treatment of schizophrenia. Previous studies have investigated the therapeutic effects of some antipsychotics on sleep variables; however, to our knowledge, the effects of brexpiprazole on sleep architecture have not been examined in patients with schizophrenia. Therefore, we aimed to exploratorily investigate the effect of brexpiprazole on sleep variables measured by polysomnography in patients with schizophrenia. This study included 10 patients with schizophrenia who were originally treated with haloperidol alone. Sleep variables of the participants were measured using polysomnography. After excluding those who did not meet the study criteria, seven patients (five men and two women; mean age [SD], 59.0 [10.0] years) were eligible for further analysis. Polysomnography was repeated at 4 weeks after the participants were prescribed brexpiprazole in addition to haloperidol. We compared the sleep architecture of the participants, measured using polysomnography, before and after taking brexpiprazole. Add-on brexpiprazole significantly prolonged rapid eye movement latency, increased the duration and percentage of stage N2 and stage N3 sleep (min, %), and decreased the duration and percentage of stage rapid eye movement sleep (min, %) at a significance level of nominal p < 0.05. Although not significant after correcting for multiple comparisons, the present results showed that add-on brexpiprazole could alter the sleep architecture of patients with schizophrenia. Future studies are warranted to replicate these findings and to further investigate the beneficial influence of brexpiprazole on sleep.

Effects of using a snooze alarm on sleep inertia after morning awakening

BackgroundMany people use the snooze function of digital alarm clocks for morning awakening, but the effects of a snooze alarm on waking are unclear. We examined the effects of a snooze alarm on sleep inertia, which is a transitional state characterized by reduced arousal and impaired cognitive and behavioral performance immediately upon awakening.MethodsIn study 1, healthy Japanese university students responded to a sleep survey during a psychology class (study 1), and we collected 293 valid responses. In study 2, we compared a separate sample of university students (n = 10) for the effects of using or not using a snooze alarm on sleep inertia immediately after awakening from normal nocturnal sleep in a sleep laboratory.ResultsOf 293 valid respondents in study 1, 251 often used a tool to wake up in the morning (85.7%). Moreover, 70.5% reported often using the snooze function of their mobile phones, mainly to reduce anxiety about oversleeping. Study 2 indicated no differences in the sleep quality or quantity before awakening with or without the snooze alarm, except in the last 20 min. However, during the last 20 min of sleep with snooze alarm, the snooze alarm prolonged waking and stage N1 sleep. Stage N1 sleep is non-rapid eye movement sleep that is primarily defined as a drowsy state. Furthermore, Global Vigor values were enhanced after awakening compared to pre-sleep in the no-snooze condition.ConclusionsUsing a snooze alarm prolongs sleep inertia compared to a single alarm, possibly because snooze alarms induce repeated forced awakenings.

Association between sleep and problematic behaviours in gifted children: a polysomnographic study.

Neurological uniqueness, maladaptive behaviours, as well as atypical sleep patterns are reported to be defining characteristics of giftedness, but this has received little empirical support. We studied the polysomnography recorded sleep of gifted and typically-developing children together with features of maladaptive behaviours. The association of sleep macrostructure and sleep instability with maladaptive behaviours was also investigated in gifted children. In all, 19 gifted children (74% boys) and 17 typically-developing children (76% boys) aged 6-12 years were studied. Giftedness was identified using Renzulli's three-factor definition. The microarousal index, number of awakenings, and number of Stage shifts between sleep stages throughout the night were computed as sleep instability parameters. Maladaptive behaviours were assessed using the Child Behaviour Checklist. We found significantly more Stage N1 and less Stage N3 in gifted children compared to typically-developing children. More Stage N1 sleep was correlated with more externalising problems and less Stage N3 sleep was correlated with more internalising problems. Gifted children also displayed more rapid eye movement (REM) sleep, but this was not significantly correlated with behavioural scales. Gifted children displayed two opposing trends of sleep instability: more instability involving N1 sleep and less instability involving N2, N3 and REM sleep. More total Stage shifts were correlated with more internalising and externalising problems. The results of this study provide initial evidence of polysomnography-based characteristics of giftedness. Further studies are needed to explore common pathways linking sleep alterations and maladaptive behaviours in children with giftedness.

Sensorimotor Cortical Activity during Respiratory Arousals in Obstructive Sleep Apnea.

Intensity of respiratory cortical arousals (RCA) is a pathophysiologic trait in obstructive sleep apnea (OSA) patients. We investigated the brain oscillatory features related to respiratory arousals in moderate and severe OSA. Raw electroencephalography (EEG) data recorded during polysomnography (PSG) of 102 OSA patients (32 females, mean age 51.6 ± 12 years) were retrospectively analyzed. Among all patients, 47 had moderate (respiratory distress index, RDI = 15−30/h) and 55 had severe (RDI > 30/h) OSA. Twenty RCA per sleep stage in each patient were randomly selected and a total of 10131 RCAs were analyzed. EEG signals obtained during, five seconds before and after the occurrence of each arousal were analyzed. The entropy (approximate (ApEn) and spectral (SpEn)) during each sleep stage (N1, N2 and REM) and area under the curve (AUC) of the EEG signal during the RCA was computed. Severe OSA compared to moderate OSA patients showed a significant decrease (p < 0.0001) in the AUC of the EEG signal during the RCA. Similarly, a significant decrease in spectral entropy, both before and after the RCA was observed, was observed in severe OSA patients when compared to moderate OSA patients. Contrarily, the approximate entropy showed an inverse pattern. The highest increase in approximate entropy was found in sleep stage N1. In conclusion, the dynamic range of sensorimotor cortical activity during respiratory arousals is sleep-stage specific, dependent on the frequency of respiratory events and uncoupled from autonomic activation. These findings could be useful for differential diagnosis of severe OSA from moderate OSA.

Ultrasound-guided stellate ganglion block improves sleep quality in elderly patients early after thoracoscopic surgery for lung cancer: a randomized controlled study

To investigate the effects of ultrasound-guided stellate ganglion block (SGB) on sleep quality in elderly patients with lung cancer early after thoracoscopic surgery. A total of 86 patients with lung cancer (ASA class I-III, aged 60-80 years) undergoing elective thoracoscopic surgery were randomized into stellate ganglion block (SGB) group (n=43) and control group (n=43) to receive ultrasound-guided right SGB with 7 mL of 0.5% ropivacaine at the C6-7 level and injection of 7 mL saline at the same site 30 min before anesthesia induction, respectively. On the day before surgery and the first two days after the surgery, sleep duration, sleep efficiency index (SEI) and N3 sleep stage of the patients were monitored using a BIS-Vista monitor, and Athens Insomnia Scale (AIS) scores were recorded. The plasma levels of norepinephrine and cortisol of the patients were measured before SGB (T1), at 5 min after extubation (T2) and at 6:00 on the first morning after the surgery (T4). Urine levels of 6-hydroxysulfate melatonin (6-HMS) were measured at 6:00 in the morning for 3 consecutive days starting on the day of surgery (T3, T4 and T5, respectively). VAS score, incidences of postoperative delirium and depression, sufentanil consumption after surgery, and discharge time of the patients were recorded. Thirty-six patients in SGB group and 35 in the control group were analyzed. In both groups, most of the patients had insomnia after surgery, but compared with those in the control group, the patients in SGB group had significantly longer sleep duration (P < 0.05) with a higher sleep efficiency index (P < 0.05) and a longer sleep time in N3 stage (P < 0.05) on the first two nights after surgery. The mean postoperative AIS score and incidence of insomnia were significantly lower in SGB group than in the control group (P < 0.05). Compared with the control group, SGB group showed significantly lower plasma levels of norepinephrine and cortisol at T2 and T4 (P < 0.05), a higher urine level of 6-HMS at T5 (P < 0.05), and a shorter discharge time after the surgery (P < 0.05). The VAS scores, postoperative incidences of delirium and depression, or postoperative sufentanil consumption did not differ significantly between the two groups. Ultrasound-guided SGB improves objective and subjective sleep quality in elderly patients early after thoracoscopic surgery for lung cancer to alleviate stress responses and sleep disorders, reduce postoperative hospital stay, and accelerate postoperative recovery of the patients.

SleepXAI: An explainable deep learning approach for multi-class sleep stage identification

Extensive research has been conducted on the automatic classification of sleep stages utilizing deep neural networks and other neurophysiological markers. However, for sleep specialists to employ models as an assistive solution, it is necessary to comprehend how the models arrive at a particular outcome, necessitating the explainability of these models. This work proposes an explainable unified CNN-CRF approach (SleepXAI) for multi-class sleep stage classification designed explicitly for univariate time-series signals using modified gradient-weighted class activation mapping (Grad-CAM). The proposed approach significantly increases the overall accuracy of sleep stage classification while demonstrating the explainability of the multi-class labeling of univariate EEG signals, highlighting the parts of the signals emphasized most in predicting sleep stages. We extensively evaluated our approach to the sleep-EDF dataset, and it demonstrates the highest overall accuracy of 86.8% in identifying five sleep stage classes. More importantly, we achieved the highest accuracy when classifying the crucial sleep stage N1 with the lowest number of instances, outperforming the state-of-the-art machine learning approaches by 16.3%. These results motivate us to adopt the proposed approach in clinical practice as an aid to sleep experts.

Different Intensities of Evening Exercise on Sleep in Healthy Adults: A Systematic Review and Network Meta-Analysis.

The effects of different intensities of evening exercise on subsequent sleep remain contradictory. Thus, this systematic review and network meta-analysis aimed to compare and rank the effects of different intensities of acute evening exercise on sleep in healthy adults with good sleep. Articles were systematically searched journals indexed in the PubMed, Web of Science, Cochrane Library, Embase, and Scopus databases from inception to the 5th of May, 2022. The basic search terms included exercise, sleep and timing, which were combined with AND. Of the 12,203 retrieved, twenty-eight studies with 325 participants met the inclusion criteria. Results revealed that there were no significant differences in terms of impacts on sleep caused by different intensities of acute evening exercise, except that when compared to no exercise, acute evening high-intensity exercise decreased rapid eye movement sleep (mean difference [MD] = -1.95%, 95% credible interval [CI] = -3.58 to -0.35). Compared to no exercise, acute evening moderate-intensity exercise was ranked as the most potential method to improve sleep, displaying a trend to improve wake time after sleep onset (MD = -2.50 min, 95% CI = -8.17 to 1.62), sleep efficiency (MD = +0.41%, 95% CI = -0.71 to 1.66), the proportion of stage N1 (MD = -0.72%, 95% CI = -2.08 to 0.71) and N3 sleep (slow-wave sleep) (MD = +0.84%, 95% CI = -1.17 to 2.78). Acute evening low-intensity exercise displayed the greatest tendency to shorten sleep onset latency (MD = -1.02 min, 95% CI = -4.39 to 2.50) compared to no exercise. Overall, regardless of intensity, acute evening exercise completed before bedtime does not disrupt subsequent sleep in healthy young and middle-aged adults.

The circadian variation of sleep and alertness of postmenopausal women.

Several factors may contribute to the high prevalence of sleep disturbances occurring in postmenopausal women. However, the contribution of the circadian timing system to their sleep disturbances remains unclear. In the present study, we aim to understand the impact of circadian factors on changes of sleep and alertness occurring after menopause. Eight healthy postmenopausal women and 12 healthy young women in their mid-follicular phase participated in an ultradian sleep-wake cycle procedure (USW). This protocol consisted of alternating 60-min wake periods and nap opportunities for ≥ 48 h in controlled laboratory conditions. Core body temperature (CBT), salivary melatonin, self-reported alertness, and polysomnographically recorded sleep were measured across this procedure. In both groups, all measures displayed a circadian variation throughout the USW procedure. Compared to young women, postmenopausal women presented lower CBT values, more stage N1 and N2 sleep, and number of arousals. They also showed a reduced amplitude of the circadian variation of melatonin, total sleep time (TST), sleep onset latency (SOL), stage N3 sleep, and alertness levels. Postmenopausal women fell asleep faster and slept more during the biological day and presented higher alertness levels during the biological night than young women. These results support the hypothesis of a weakened circadian signal promoting sleep and wakefulness in older women. Aging processes including hormonal changes may be main contributors to the increased sleep-wake disturbances after menopause.

Effects of CPAP Treatment on Electroencephalographic Activity in Patients with Obstructive Sleep Apnea Syndrome During Deep Sleep with Consideration of Cyclic Alternating Pattern.

To investigate whether continuous positive airway pressure (CPAP) treatment would change EEG activities associated with cyclic alternating pattern (CAP subtype A1, A2, and A3) and non-CAP (NCAP) during non-rapid eye movement sleep stage 3 (N3) in patients with obstructive sleep apnea (OSA). The effects of CPAP treatment on the percentages of sleep stage N3 occupied by the CAP and NCAP, power of EEG waves in the CAP and NCAP were examined in 18 patients with moderate-to-severe OSA undergoing polysomnographic recordings. Apnea and hypopnea index during sleep stage N3 was positively correlated with ratios of phases A2 and A3 duration to total phase A duration [Phase (A2+A3) /Phase A] and negatively correlated with phase A1/phase A. With CPAP treatment, percentages of sleep stage N3 occupied by total CAPs and subtypes A2 and A3, as well as CAP A2 and CAP A3 indexes were significantly decreased while percentages of sleep stage N3 occupied by NCAP (NCAP/N3) and CAP A1 index were significantly increased. In addition, CPAP treatment significantly decreased percentage of respiratory events associated CAPs and increased percentage of non-respiratory related CAPs. Moreover, absolute and relative delta power was significantly increased during phase A1, unchanged during phase A2 and phase B2, and significantly decreased during phases B1, A3 and B3. The absolute power of faster frequency EEG waves in CAPs showed a general trend of decrease. The absolute and relative power of delta waves with amplitudes ≥75 μV, but not <75 μV, was significantly increased. CPAP treatment improves the sleep quality in OSA patients mainly by increasing delta power and decreasing power of higher frequency waves during phase A1, and decreasing CAP A2 and A3 indexes as well as increasing NCAP/N3 and power of delta waves with amplitudes ≥75 μV during NCAP.

Thalamocortical coherence and causality in different sleep stages using deep brain stimulation recordings

Previous research has shown an interplay between the thalamus and cerebral cortex during NREM sleep in humans, however the directionality of the thalamocortical synchronization is as yet unknown. In this study thalamocortical connectivity during different NREM sleep stages using sleep scalp electroencephalograms and local field potentials from the left and right anterior thalamus was measured in three epilepsy patients implanted with deep brain stimulation electrodes. Connectivity was assessed as debiased weighted phase lag index and granger causality between the thalamus and cortex for the NREM sleep stages N1, N2 and N3. Results showed connectivity was most prominently directed from cortex to thalamus. Moreover, connectivity varied in strength between the different sleep stages, but barely in direction or frequency. These results imply relatively stable thalamocortical connectivity during NREM sleep directed from the cortex to the thalamus.