Higher Non-rapid Eye Movement Research Articles

Abnormal Sleep Signals Vulnerability to Chronic Social Defeat Stress.

There is a tight association between mood and sleep as disrupted sleep is a core feature of many mood disorders. The paucity in available animal models for investigating the role of sleep in the etiopathogenesis of depression-like behaviors led us to investigate whether prior sleep disturbances can predict susceptibility to future stress. Hence, we assessed sleep before and after chronic social defeat (CSD) stress. The social behavior of the mice post stress was classified in two main phenotypes: mice susceptible to stress that displayed social avoidance and mice resilient to stress. Pre-CSD, mice susceptible to stress displayed increased fragmentation of Non-Rapid Eye Movement (NREM) sleep, due to increased switching between NREM and wake and shorter average duration of NREM bouts, relative to mice resilient to stress. Logistic regression analysis showed that the pre-CSD sleep features from both phenotypes were separable enough to allow prediction of susceptibility to stress with >80% accuracy. Post-CSD, susceptible mice maintained high NREM fragmentation while resilient mice exhibited high NREM fragmentation, only in the dark. Our findings emphasize the putative role of fragmented NREM sleep in signaling vulnerability to stress.

Electroencephalographic abnormalities are correlated with cognitive deficits in children with benign childhood epilepsy with centrotemporal spikes: A clinical study of 61 cases

ObjectiveThe objective of this study was to explore the effect of spikes on cognition in patients with benign childhood epilepsy with centrotemporal spikes (BECTS) and to identify electroencephalography (EEG) markers enabling early detection of cognitive impairment. MethodsSixty-one children with BECTS diagnoses and 60 age- and education-matched healthy controls were enrolled. Four-hour EEG recordings were analyzed for each patient to check for interictal spikes, high-frequency oscillations (HFOs), nondipole spikes, and other atypical EEG features and to examine the spike–wave index of nonrapid eye movement (NREM) sleep. All 121 children underwent a series of neuropsychological tests to assess cognitive function. ResultsPatients with a high NREM sleep discharge index (≥55%) in the first sleep cycle exhibited significantly lower scores for arithmetic calculation, executive function, and attention and memory tests than patients with a low discharge index (<55%). Eight patients with HFOs exhibited even poorer performance than HFO-negative patients for arithmetic calculation, executive function, vocabulary comprehension, visual perception, vocal perception, spatial memory ability, and response ability. Children with bilateral discharge exhibited poorer ability in three-dimensional spatial imaging test, poorer memory, and slower response than did those with unilateral discharge (P < .05). Nondipole spikes, multiple asynchronous discharges, and generalized spike–wave discharges respectively had an impact on calculation ability, memory, and reaction ability respectively (P < .05). ConclusionsSpike frequencies in stage 3 and 4 sleep varied from those observed in stage 1 and 2 sleep; the highest spike frequency was in stage 2 sleep. High NREM sleep discharge index (i.e., ≥55%) and HFOs were linked to the highest risk for cognitive deficit, while bilateral discharges, nondipole spikes, multiple asynchronous discharges, and generalized spike–wave discharges were less indicative of cognitive impairment.

Abnormal Sleep Signals Vulnerability to Chronic Social Defeat Stress

There is a tight association between mood and sleep as disrupted sleep is a core feature of many mood disorders. There is a paucity in available animal models for investigating the role of sleep in the etiopathogenesis of depression. Therefore, we aimed to assess whether prior sleep disturbances can predict susceptibility to future stress using the chronic social defeat (CSD) stress paradigm.Pre-CSD, mice susceptible to stress displayed increased fragmentation of Non-Rapid Eye Movement (NREM) sleep, due to increased switching between NREM and wake and a higher percentage of NREM bouts with short duration, relative to resilient mice. The pre-CSD sleep features from both phenotypes were separable enough to allow prediction of susceptibility to stress with >80% accuracy. Post-CSD, susceptible mice maintained the enhanced NREM fragmentation while resilient mice exhibited high NREM fragmentation, only in the dark.Our findings emphasized the putative role sleep plays in signaling vulnerability to stress.

Visually detected NREM Stage 2 sleep spindles in kindergarten children are associated with current and future emotional and behavioural characteristics

Sleep electroencephalogram spindles are associated with efficient cortical-subcortical connectivity, and intellectual and learning abilities. In the present study, we assessed healthy preschoolers with a twofold aim: (i) to explore associations of non-rapid eye movement S2 spindles with emotional/behavioural characteristics cross-sectionally; and (ii) longitudinally. A total of 43 children who were 5years old underwent objective sleep electroencephalogram monitoring in their homes. Emotional and behavioural dimensions were assessed by parents and teachers with the Strengths & Difficulties Questionnaire at baseline and at follow-up 1year later. Non-rapid eye movement S2 spindles were visually scored and compared with Strengths & Difficulties Questionnaire dimensions. High non-rapid eye movement S2 spindle density was associated with less internalizing behaviour, more prosocial behaviour and a low total problem score. In girls, high non-rapid eye movement S2 spindle density was related to low hyperactivity, while in boys it was associated with less internalizing behaviour, more externalizing behaviour and more hyperactivity. Longitudinally, a higher number of non-rapid eye movement S2 spindles at 5years old predicted fewer peer problems 12months later. In kindergarten children, high non-rapid eye movement S2 spindle density is associated with observable current and future favourable emotional/behavioural patterns. However, gender differences were also found, as should be taken into account in future studies.

NREM-AHI greater than REM-AHI versus REM-AHI greater than NREM-AHI in patients with obstructive sleep apnea: clinical and polysomnographic features

Previous studies show a high prevalence of obstructive sleep apnea (OSA) patients with a higher non-rapid eye movement (NREM) apnea-hypopnea index (AHI) (NREM-AHI) than rapid eye movement (REM) AHI (REM-AHI). However, the clinical significance of this phenomenon in patients with OSA is unknown. This study aimed to investigate whether there were significant differences in clinical and polysomnographic features between the NREM-AHI > REM-AHI group and the REM-AHI > NREM-AHI group and to determine whether NREM-AHI > REM-AHI or REM-AHI > NREM-AHI is a specific clinical entity. One hundred forty-two patients with OSA, including 114 males and 28 females, were assessed for specific sleep-related complaints using a semistructured clinical questionnaire, for daytime sleepiness using the Epworth Sleepiness Scale (ESS), for depression using the Beck Depression Inventory (BDI), and for health-related quality of life using the Medical Outcomes Study Short-Form 36 Health Survey questionnaire (SF-36). Anthropometric, clinical, and polysomnographic characteristics were examined between patients with NREM-AHI > REM-AHI and those with REM-AHI > NREM-AHI. A higher NREM-AHI than REM-AHI was found in 54.9% of the 142 patients with OSA. Overall, males predominated in each group, and there were no significant differences in age, body mass index, medical history, and drug intake between the NREM-AHI > REM-AHI group and the REM-AHI > NREM-AHI group. A high occurrence of NREM-AHI > REM-AHI (94.9%) or REM-AHI > NREM-AHI (90.6%) was found in moderate-to-severe cases each group. Although several indexes of OSA were worse in the NREM-AHI > REM-AHI group than in the REM-AHI > NREM-AHI group, no significant differences in specific sleep-related complaints, ESS score, BDI score, the incidence of daytime sleepiness or depression, and scores of sub-dimensions and the total score on SF-36 were present between the two groups. As compared separately, no significant differences in clinical features were observed in the clinical data for males and females between the two groups. Our results show that either NREM-AHI > REM-AHI or REM-AHI > NREM-AHI is more common in moderate-to-severe OSA cases, and there are no significant differences in clinical features between the NREM-AHI > REM-AHI group and the REM-AHI > NREM-AHI group. These findings may suggest that either NREM-AHI > REM-AHI or REM-AHI > NREM-AHI should be considered as a part of the spectrum of OSA, rather than a specific clinical entity.

Half of patients with obstructive sleep apnea have a higher NREM AHI than REM AHI

Background and purposeTo determine the percentage of sequential patients with obstructive sleep apnea with a higher non-rapid eye movement (NREM) apnea–hypopnea index (AHI) than rapid eye movement (REM) AHI and those with a higher REM AHI than NREM AHI, and to look for factors that might influence the AHI to be higher in one of these two groups versus the other and thus ascertain the factors that cause an AHI to be higher in NREM than REM. A high body mass index (BMI) and a supine body position are well known as exacerbating factors for obstructive sleep apnea (OSA). Males, as well as older individuals, are generally more predominantly affected with OSA than females. Usually OSA is worse in REM sleep than in NREM sleep, although this is not always true. MethodsA retrospective study of sequential patients from one month's admission to a single sleep laboratory was conducted. We determined the age, sex, BMI, body position, duration of apnea, amount of time spent in REM and oxygen desaturation in patients who had a higher NREM AHI than REM AHI versus those who had a higher REM AHI than NREM AHI. To minimize variability, the sleep studies were scored by a single individual. ResultsA higher NREM AHI than REM AHI was found in 50% of the 66 patients with OSA. Males predominated in each group and there was no age difference between the groups. Although AHI for both groups tended to become higher with an increase in BMI, the BMI was not statistically different between the two experimental groups. OSA was worse in the supine position in both experimental groups consistent with previous literature. Percentage of time spent in REM or the duration of the apnea did not determine whether a patient fell into the NREM AHI>REM AHI group versus the REM AHI>NREM AHI. The severity of oxygen desaturation was not significantly different between the NREM AHI>REM AHI versus the REM AHI>NREM AHI group. However, when we combined and analyzed the two groups as a whole, the apneas were longer in REM, consistent with previous literature. ConclusionsAlthough it is well known that OSA is generally worse in REM sleep because of the degree of desaturation and duration of apnea, a higher NREM AHI than REM AHI is found in up to one half of individuals. Most of the usual predictors for severity of OSA as a whole did not discriminate these groups. Further work needs to be done to determine the factors that discriminate these two groups and thus make AHI higher in NREM than REM.