Sleep and the gut microbiota in preschool aged children

Sleep plays a significant role in the mental and physical development of children. Emerging evidence in animals and human adults indicates a relationship between sleep and the gut microbiota; however, it is unclear whether the sleep of preschoolers during a key developmental period, associates with features of their gut microbiota. The objective of this study was to assess the relationship between sleep and gut microbiota in preschool aged children (4.37 ±0.48 years, n=143). Sleep measures included total nighttime sleep (TST), sleep efficiency (SE), and wake-time after sleep onset (WASO) assessed using actigraphy. Beta-diversity differences between children with low and high TST (p =0.048) suggest gut microbiota community differences. Particularly, relative abundance of Bifidobacterium was higher in the high TST group and Bacteroides, was higher in children who had higher SE and low WASO (LDA score >2). In contrast, some Lachnospiraceae members including Blautia and Coprococcus 1 were associated with shorter nighttime sleep duration and less efficiency, respectively. We also found a group of faecal metabolites, including specific neuroactive compounds and immunomodulating metabolites were associated with greater sleep efficiency and less time awake at night. Notably, tryptophan and its metabolizing products were higher in children who had higher SE or lower WASO (LDA score >2); concentration of propionate was higher in children with lower WASO (p =0.036). Overall, our results reveal a novel association between sleep and gut microbiota in preschool aged children. Longer nighttime sleep and greater sleep efficiency were associated with specific commensal bacteria that may regulate sleep through modulating neurotransmitter metabolism and the immune system.

Association of Allergic Symptoms in the First 2 Years of Life With Sleep Outcomes Among Chinese Toddlers

Background: Previous studies have linked allergic symptoms to sleep in children, but the associations might be different when considering different types of allergic symptoms or sleep outcomes. Moreover, the combined effects of multiple allergic symptoms remain unclear in early life. This study aimed to investigate the associations between multiple allergic symptoms and sleep outcomes in early life.Methods: We included 673 toddlers aged 2 years from a birth cohort in Guangzhou, China. We identified allergic symptoms (skin, eyes and nose, gastrointestinal tract, mouth and lips, and wheeze) within 2 years via standard questionnaires. Sleep outcomes including sleep duration and quality over the past month were assessed based on the Chinese version of the Brief Infant Sleep Questionnaire. Associations between allergic symptoms and sleep outcomes were examined using multivariable linear regression and logistic regression.Results: Compared to children without allergic symptoms, children with allergic nasal and ocular symptoms had higher odds of frequent nighttime awakenings (OR = 1.41; 95% CI: 1.03, 1.93) and irregular sleep (OR = 1.45, 95% CI: 1.05, 2.00); children with allergic gastrointestinal symptoms slept 0.28 h less during nighttime (95% CI: −0.48, −0.07) and 0.25 h less per day (95% CI: −0.43, −0.08), and had 59% higher odds of irregular sleep (95% CI: 1.24, 2.04). We also found significant association of multiple allergic symptoms with shortened nighttime sleep duration and increased irregular sleep. Whereas, allergic skin, mouth and lips, and wheeze symptoms were not significantly associated with sleep outcomes.Conclusion: Allergic symptoms within 2 years of age were adversely associated with sleep outcomes, which highlight the importance of early screening of allergic symptoms in toddlers in order to improve their sleep outcomes.

Early Daytime Sleepiness and Nighttime Slow-wave Sleep Disorganization in Progressive Macaque Model of Parkinson’s Disease

Parkinsonian patients often experience wake/sleep behavior disturbances, which can appear at an early stage of the disease in a way that is still not fully described. We aimed here at reproducing and characterizing these clinical signs in a progressive non-human primate model of the Parkinson’s disease to better understand the underlying physiopathology and to identify biomarkers of the disease. Three adult non-human primates (macaca fascicularis) were equipped with a polysomnographic telemetry system allowing the characterization of the wake/sleep behavior by long-term neurophysiological recordings and a modified multiple sleep latency test. Experiments were first performed in healthy animals and then during the progressive induction of a parkinsonian syndrome by chronic intramuscular injections of low doses of MPTP. We observed a significant early onset of wake/sleep behavior disturbances, before any motor symptoms, resulting in (i) a disorganization of nighttime sleep with more deep sleep and (ii) a disorganization of daytime naps with an excessive daytime sleepiness characterized by longer duration of naps, which occurred faster. These observations persisted and worsened in stable symptomatic state. In that latter state, we observed persistent excessive daytime sleepiness and more disorganized nighttime sleep architecture and continuity. Interpolating to the human condition, the present study suggests that nighttime and daytime sleep disorders may appear in early stage of the disease. They could thus be used as biomarkers of the disease for early stratification of patients who are at risk of developing Parkinson’s disease.

Nighttime Sleep Awakening Frequency and Its Consistency Predict Future Academic Performance in College Students

Although the relations between sleep and academic performance have been extensively examined, how sleep predicts future academic performance (e.g., 2 -3 years) remains to be further investigated. Using wearable smartwatches and a self-report questionnaire, we tracked sleep activities of 45 college students over a period of approximate half a month to see whether their sleep activities predicted their academic performance, which was estimated by grade point average (GPA). Results showed that both nighttime sleep awakening frequency and its consistency in the tracking period were not significantly correlated with the GPA for the courses taken in the semester during sleep tracking (current GPA). However, both nighttime sleep awakening frequency and its consistency inversely predicted the GPA for the rest of the courses taken after that semester (future GPA). Moreover, students with more difficulty staying awake throughout the day obtained lower current and future GPAs, and students with lower inconsistency of sleep quality obtained lower future GPA. Together, these findings highlight the importance of nighttime sleep awakening frequency and consistency in predicting future academic performance and emphasize the necessity of assessing the consistency of sleep measures in future studies.

Habitual Sleep, Sleep Duration Differential, and Weight Change Among Adults

We assessed longitudinal associations between diary-measured sleep duration and clinically assessed body mass index (BMI) among 784 men and women enrolled in the Wisconsin Sleep Cohort Study (mean [SD] age = 51.1 [8.0] years at baseline). The outcome was BMI (kg/m2). Key predictors were habitual sleep duration (defined as average weekday nighttime sleep duration) and sleep duration differential (defined as the difference between average weekday and average weekend nighttime sleep duration) at each data collection wave. Men with shorter habitual sleep duration on weekdays had higher BMI than men with longer habitual sleep duration on weekdays. Participants with larger differentials between weekday and weekend sleep duration experienced more rapid BMI gain over time for both men and women. Inadequate sleep, characterized as shorter habitual sleep during weekdays and larger weekday-weekend sleep differential, is positively associated with BMI levels and trajectories among men and women in mid-to-late life.

Daily Sleep, Well-Being, and Adult Day Services Use Among Dementia Care Dyads

Sleep is critical for health and well-being among both persons with dementia (PwD) and their family caregivers (CG). This study described sleep characteristics for dementia family care dyads, then examined the associations with sleep quality, daytime functioning, and mood in the context of Adult Day Services (ADS) use. Caregivers (n = 173) reported daily bedtime, wake time, and sleep quality for themselves and the persons with dementia across 8 consecutive days (N = 1,359), where PwD attended ADS at least 2 days of the week. They also reported their own fatigue and affect and PwD’s daytime and nighttime sleep and behavior problems on each day. Findings from multilevel models suggested that bedtime was earlier and total time in bed was shorter before an ADS day for the dyad, and also on an ADS day for PwD; wake time was earlier for the dyad on and following an ADS day. Using ADS related to better prior night sleep quality for PwD; it also weakened the association between nighttime sleep problems and higher daytime negative affect for CG. Yesterday’s ADS use buffered the negative impact of shorter total time in bed on CG daytime fatigue; it also buffered the association between nighttime sleep problems and lowered CG daytime positive affect. Regular ADS use may protect against the adverse impact of sleep disturbances on daytime functioning and well-being for dementia care dyads.

Association Between Evening Light Exposure and Subjective Sleep Measures Among People Living With Dementia

Excessive light exposure before bedtime can disrupt one’s circadian rhythm and can lead to poor sleep. The purpose of this study was to describe the relationship between evening light exposure and subjective sleep measures in people living with dementia (PLWD). We conducted secondary data analysis using the baseline data from Healthy Patterns Clinical Trial (N=137). We used Actiwatch Spectrum Plus to collect light data over three consecutive days. We defined evening light exposure as the average white light intensity for 4 hours before sleep. Sleep measures included Epworth Sleepiness Scale and PROMIS Sleep-Related Impairment. We used univariate regression analysis. We found that that greater evening intensity of light exposure was associated with higher daytime sleepiness (𝛽=0.209, p=0.015) and more sleep impairment (𝛽=0.228, p=0.014). The results of our study suggest that exposure to bright light during evening can disturb nighttime sleep and increase daytime sleepiness in PLWD.

Bedtime to the brain: How infants sleep habits intertwine with sleep neurophysiology

Adequate sleep is critical for development and facilitates the maturation of the neurophysiological circuitries at the basis of cognitive and behavioral function. Observational research has associated sleep problems in early life with worse later cognitive, psychosocial, and somatic health outcomes. Yet, the extent to which day-to-day sleep habits in early life relate to neurophysiology - acutely and long-term - remains to be explored. Here, we report that sleep habits in 32 healthy 6-month-olds assessed with actimetry are linked to fundamental aspects of their neurophysiology measured with high-density electroencephalography (hdEEG). Our study reveals four key findings: First, daytime sleep habits are linked to EEG slow wave activity (SWA). Second, habits of nighttime movement and awakenings from sleep are connected with spindle density. Third, habitual sleep timing is linked to neurophysiological connectivity quantified as Delta-coherence. And lastly, Delta-coherence at age 6 months predicts nighttime sleep duration at age 12 months. These novel findings widen our understanding that infants' sleep habits are closely intertwined with three particular levels of neurophysiology: sleep pressure (determined by SWA), the maturation of the thalamocortical system (spindles), and the maturation of cortical connectivity (coherence). Our companion paper complements this insight in the perspective of later developmental outcomes: early thalamocortical connectivity (spindle density) at age 6 months predicts later behavioural status at 12 and 24 months. The crucial next step is to extend this concept to clinical groups to objectively characterize infants' sleep habits "at risk" that foster later neurodevelopmental problems.

Is It Time We Stop Discouraging Evening Physical Activity? New Real-World Evidence From 150,000 Nights

Professional and colloquial sleep hygiene guidelines advise against evening physical activity, despite meta-analyses of laboratory studies concluding that evening exercise does not impair sleep. This study is the first to investigate the association between objectively measured evening physical activity and sleep within a real-world big-data sample. A total of 153,154 nights from 12,638 individuals aged 18–60 years (M = 40.1 SD = 10.1; 44.5% female) were analyzed. Nighttime sleep and minutes of physical activity were assessed using Polar wearable devices for 14 consecutive days. Thirty minutes or more of moderate-to-near maximal physical activity during the 3 h before sleep onset were recorded in 12.4% of evenings, and were more frequent on weekdays than weekends (13.3 vs. 10.2% respectively, p < 0.001). Linear mixed modeling revealed that sleep efficiency was not significantly associated with evening physical activity, and that sleep duration was 3.4 min longer on average on nights following evenings in which participants engaged in 30 min or more of moderate-intense physical activity. Effects were found for sleep timing metrics, as evening physical activity was linked with earlier sleep onset and offset times (−13.7 and −9.3 min, respectively). Overall, these effects were greater– but still very small– on weekdays compared to weekends. The present study provides further evidence for the lack of meaningful links between sleep duration or quality and physical activity in the hours preceding sleep. Taken together with recent meta-analytic findings, these findings suggest that changes in public health recommendations are warranted regarding evening physical activity and its relation to sleep.