bluuebunny/crossref_metadata_2025_split huggingface dataset:
012 Overnight light exposure acutely increases heart rate during sleep and decreases insulin sensitivity the following day
Authors: Grimaldi Daniela , Reid Kathryn , Mason Ivy , Warlick Chloe , Malkani Roneil , Abbott Sabra , Zee Phyllis 
Published: May 2021

Abstract

Introduction
Prior reports indicate that exposure to light at night negatively impacts sleep quality, autonomic and metabolic function, but the interaction between these physiologically interconnected systems is not fully elucidated. We examined the acute effects of nighttime light exposure on sleep macro and microarchitecture, heart rate (HR) and response to oral glucose tolerance test (OGTT), and the relationship between these measures.

Methods
Twenty healthy adults (18 - 40 years) were randomized into Light or Dark groups and run in parallel for a three-day and two-night laboratory stay. The Light group (n=10) slept in the dark (&lt; 3 lux) on Night 1 and slept with overhead room lights on (100 lux) on Night 2, while the Dark group (n=10) slept in the dark (&lt; 3 lux) on both Nights 1 and 2. Overnight polysomnography (PSG) was used to assess sleep macro and microstructure (slow wave activity: SWA: 0.5–4 Hz, and slow oscillatory (SO) activity: 0.5–1 Hz), and beat-to-beat measurement of HR. A two-hour OGTT was completed each morning. The between groups change in PSG-derived measures and metabolic parameters from Night/Day 2 to Night/Day 1, was calculated.

Results
While a greater percentage of time was spent in stage 2 (p= 0.003) and a smaller percentage of time was spent in stage 3 (p= 0.04), there were no between group differences in SWA and SO activity. Time series analysis of HR changes across the night from Night 1 to Night 2 showed higher HR in the Light vs the Dark group (p&lt; 0.001). The change from Day 1 to Day 2 of the initial insulin response (60-min. area under the curve, AUC) showed a higher insulin response in the Light vs the Dark group (p= 0.029). The change in HR was positively correlated with the change in the 60-min. AUC of insulin (R= 0.46, p= 0.049).

Conclusion
A single overnight light exposure acutely increases heart rate during sleep and decreases insulin sensitivity the following day and these responses appear to be associated, suggesting that elevated autonomic activity in response to light at night impacts next day metabolic responses.

Support (if any)
Center for Circadian and Sleep Medicine, UL1TR001422
013 Associations Between Rest-Activity Rhythms and Nocturnal Blood Pressure are Sex-Dependent in Apparently Healthy Emerging Adults
Authors: Hoopes Elissa , Patterson Freda , Berube Felicia , D’Agata Michele , Brewer Benjamin , Malone Susan , Farquhar William , Witman Melissa 
Published: May 2021

Abstract

Introduction
Misalignment between endogenous circadian rhythms and environmental signals – an emerging risk factor for cardiovascular disease (CVD) – can disrupt diurnal blood pressure (BP) rhythms, resulting in higher nocturnal BP and less-pronounced BP dipping (i.e., % decline in nighttime systolic BP [SBP] relative to daytime values). Daily patterns of rest and activity (‘rest-activity rhythms’ [RAR]) are a proxy for estimating circadian disruption in free-living settings and have been independently associated with elevated CVD risk. However, the relation between RAR and nocturnal BP is unclear. Thus, we aimed to quantify the associations between RAR and nocturnal BP characteristics in male and female emerging adults (18-25y).

Methods
Fifty healthy emerging adults (20±1y; 20M/30F) underwent 24-h ambulatory BP monitoring following 14 consecutive days of continuous wrist actigraphy. RAR variables of interdaily stability (IS; day-to-day consistency in RAR), intradaily variability (IV; within-day fragmentation of RAR), and relative amplitude (RA; difference between trough vs. peak activity) were computed. Bivariate correlations were used to quantify associations between RAR variables and nocturnal BP characteristics for all participants, and separately for males and females. Linear regression models of mean nocturnal SBP, nocturnal diastolic BP (DBP), and SBP dipping were also generated to test main and interactive effects of sex and RAR. Potential confounders (variables associated with outcomes at p&lt;0.10) of daytime BP, race, body mass index, physical activity, sleep duration, alcohol, caffeine, and sodium intake were also included as indicated.

Results
Overall, IS and RA positively correlated with % SBP dipping (IS: r=0.33, p=0.02; RA: r=0.35, p=0.01). Among females only, correlations strengthened (IS: r=0.50, p&lt;0.01; RA: r=0.52, p&lt;0.01) and an inverse association between RA and mean nocturnal SBP emerged (r=-0.46, p=0.01). Conversely, among males, no significant associations were apparent. Multivariate regressions revealed a significant sex*RAR interaction, such that in females, every 1-standard deviation increase in IS and RA were associated with an average decrease in nocturnal SBP of 5.4 mmHg (95% CI: -10.0, -0.73) and 4.8 mmHg (95% CI: -9.2, -0.34), respectively.

Conclusion
Findings suggest that consistent and high-amplitude RAR associate with more favorable nocturnal BP characteristics, particularly in emerging female adults.

Support (if any)
Supported in part by NIH P20-GM113125.
021 Poor sleep quality in traumatic brain injury patients is associated with elevated inflammatory biomarkers
Authors: Pucci Josephine , Mithani Sara , Leete Jacqueline , Lai Chen , Kenney Kimbra , Gill Jessica , Werner J Kent 
Published: May 2021

Abstract

Introduction
Mild traumatic brain injury (mTBI) and sleep disorders are independently associated with inflammation. Following mTBI, elevated levels of cytokines, such as interleukin-6 (IL-6), 10 (IL-10) and tumor necrosis factor alpha (TNFα), have been observed. These signals are also known to modulate sleep homeostasis. IL-6, IL-10 and TNFα concentrations are typically measured in plasma, but recent work has shown that their measurement in extracellular vesicles (EVs) may hold additional value, as they are shielded from degradation and may be more biologically relevant. We hypothesized that inflammatory biomarkers in chronic mTBI patients would be elevated in poor sleepers.

Methods
In a cross-sectional cohort of warfighters (n=137 mTBI, 44 controls), the Pittsburgh Sleep Quality Index (PSQI) was compared with EV and plasma IL-6, IL-10, TNFα. Protein quantification was performed with Simoa. Two-tailed tests were used with a type I error of p&lt;0.05. Linear models controlled for age, sex, and body mass index.

Results
In the mTBI cohort, poor sleepers (PSQI&gt;=10, a published military cutoff) had elevated IL-6 vs. good sleepers (mean [SD] pg/mL, EV: 0.47 [0.63] vs 1.01 [1.54], p=0.04, d=0.44; plasma: 5.00 [13.31] vs 6.88 [13.51], p=0.03, d=0.14). Poor sleepers with mTBI had less EV IL-10 (1.71 [8.18] vs 0.30 [0.54], p=0.017). Comparisons of plasma IL-10 were not significant. No differences in TNFα were observed in mTBI groups. In our model, PSQI was the strongest predictor of EV IL-6 (βstd=0.27, p=0.03) in mTBI patients, whereas only BMI predicted IL-6 in controls. EV IL-6, IL-10, and TNFα correlated with PSQI (R=0.21, p=0.019; R=0.21, p=0.014; R=0.22, p=0.013, respectively), but these relationships were not found with plasma. In controls, no correlations or differences in any biomarker were observed between groups.

Conclusion
Warfighters who report poor sleep had significantly elevated inflammatory biomarkers after chronic mTBI. Cytokine levels in EVs had greater effect sizes between groups compared to plasma levels suggesting EV measurements may have improved signal. Poor sleep and its association with inflammatory cytokines after mTBI may have therapeutic implications.

Support (if any)
DoD: Contract W91YTZ-13-C-0015/ HT0014-19-C-0004 with VHA Central Office VA TBI Model Systems Program of Research/DHA Contracting Office (CO-NCR) HT0014
037 Subjective sleep and objective cognition in middle-aged and older adults: Does sex matter?
Authors: Curtis Ashley , Schmiedeler Anthony , Jagannathan Sadhika , Connell Maggie , Atkinson Angela , Miller Mary Beth , McCrae Christina S 
Published: May 2021

Abstract

Introduction
Worse sleep has been linked to cognitive dysfunction in aging populations. There are known sex differences in the prevalence and presentation of both sleep disturbance and cognitive impairment, but research investigating sex differences in the associations between sleep and objective cognition is limited and inconclusive. We examined sex as a moderator of associations between self-reported sleep and objective cognitive performance in middle-aged/older adults.

Methods
Sixty-four adults aged 50+ (Mage= 63.8, SD=7.7; 33 men/31 women) who were cognitively healthy (no mild cognitive impairment, dementia or neurological disorders) completed an online survey (via Qualtrics) measuring self-reported sleep (Pittsburgh Sleep Quality Index; PSQI). Participants completed online cognitive tasks (via Inquisit) measuring inhibition (Stroop task; interference reaction time scores), attentional orienting (Posner Endogenous Cueing Task; reaction time difference between invalidly cued and validly cued trials), and working memory (Sternberg task; proportion correct). Multiple regressions examined whether PSQI subscores (sleep quality, sleep duration, sleep efficiency) were independently associated with or interacted with sex in their associations with cognition, controlling for age and education.

Results
Sex interacted with sleep quality in the association with endogenous attentional orienting (p=.01, R-squared=.10). Specifically, worse sleep quality was associated with worse attentional orienting in women (B=22.73, SE=9.53, p=.02) but not men (p=.24). Sex interacted with PSQI-sleep duration (p=.03, R-squared=.08) and PSQI-sleep efficiency (p=.03, R-squared=.08) in the association with inhibition performance. Specifically, worse sleep duration (B=235.28, SE=77.51, p=.004) and sleep efficiency (B=211.73, SE=68.70, p=.003) were associated with worse interference scores in men but not women (ps&gt;.05). No variables were associated with working memory.

Conclusion
In middle-aged and older adults, sex moderates associations between self-reported sleep and objective cognition, depending on the sleep parameter and cognitive ability assessed. Findings suggest that women are more vulnerable to the effects of poor sleep quality on spatial attention, whereas men are more vulnerable to the effects of shorter sleep duration and worse overall sleep fragmentation on ability to inhibit task-irrelevant stimuli. Future studies should investigate sex-specific associations between sleep and cognition over time in order to better understand the prospective trajectories of these processes during aging.
Support (if any):
048 Increased Cognitive Load Under Stress Modulates Sleep Spindles and Slow Oscillations in a Sleep-Stage Dependent Manner
Authors: Natraj Nikhilesh , Neylan Thomas , Yack Leslie , Mathalon Daniel , Richards Anne 
Published: May 2021

Abstract

Introduction
The effect of increased cognitive load especially under duress has been known to affect brain rhythms in humans. However, this effect has been shown primarily in the awake brain; the effect of stressful cognitive load on sleep rhythms is yet unclear. We leveraged a unique opportunity to understand the effect of cognitive load under laboratory stress on sleep spindles and slow oscillations that are hallmark rhythms of NREM sleep.

Methods
Cortical 6-channel EEG nap data were collected from 45 subjects over two separate days: after a control session without laboratory stressors and after an experimental session in which they underwent fear condiitoning and negative-emotional-image viewing sessions. We detected sleep spindles (11-13Hz over frontal regions and 13-16Hz over centroposterior regions) and slow oscillations (0.16–1.25Hz oscillations) as discrete events at each of the six electrodes, and staged them by the sleep hypnogram. We evaluated the spindle rate in N2 sleep and the proportion of slow oscillations nested with a spindle in N3 sleep.

Results
Over all 6 EEG electrodes, N2 spindle rates increased on average by 14% in the experimental session compared to the control session (mixed-effect models p&lt;0.001). In addition, over all 6 electrodes, the proportion of slow oscillations in N3 nested with a spindle increased by 2.3% in the experimental session compared to the control session (mixed effect model, p=0.005).

Conclusion
We show for the first time how increased cognitive load under stressful laboratory conditions affects sleep rhythms. Such an increased response in sleep might correspond to a continued emotional response due to the cognitive load under duress. Ongoing work seeks to tie these findings to possible emotional memory consolidation.

Support (if any)
VA Career Development Award to Dr. Richards (5IK2CX000871-05)
063 Differential Impact of Sleep Duration on Nocturnal Blood Pressure Dipping Between Men and Women
Authors: Bigalke Jeremy , Greenlund Ian , Nicevski Jennifer , John-Henderson Neha , Carter Jason 
Published: May 2021

Abstract

Introduction
There is growing evidence that poor sleep may have a greater impact on the development of cardiovascular complications in women compared to men. However, most studies that have evaluated the impact of sex on sleep insufficiencies and blood pressure (BP) have not utilized ambulatory BP, and often rely more heavily on subjective sleep diaries as opposed to objective sleep assessment. The purpose of this study was to examine the impact of sex on the relationship between objectively measured sleep and nocturnal BP dipping. We hypothesized that poor sleep would be associated with decreased nocturnal BP dipping, and that this association would be stronger in women.

Methods
Total sleep time (TST) and sleep efficiency (SE) were monitored in fifty adults (31 men, 19 women; 36±3 years; 26±1 kg/m2) utilizing wrist actigraphy monitoring over the course of 5–14 days (Avg: 10±0 days). On a separate occasion, participants underwent a 24-hour ambulatory BP recording session. Independent samples T-tests were used to compare characteristics between sexes. Partial correlations controlling for age and BMI were utilized to probe relationships between sleep and nocturnal BP dipping.

Results
TST and SE were not different between sexes. However, women exhibited reduced mean arterial pressure (MAP: 86±1 vs. 90±1 mmHg, P=0.026) compared to men. Partial correlation revealed a significant relationship between TST and the magnitude of nocturnal MAP dipping in the sample population (R = 0.460, P&lt;0.001). When stratified by sex, this significant relationship persisted in men (R = 0.610, P&lt;0.001), but not women (R = 0.108, P&gt;0.05). In contrast, no relationship was observed between SE and nocturnal MAP dipping (R = -0.052, P&gt;0.05) for the sample population. Similarly, SE did not correlate with nocturnal MAP dipping in men (R = -0.080, P&gt;0.05) or women (R = 0.045, P&gt;0.05).

Conclusion
Contrary to our initial hypothesis, our results demonstrate that actigraphy-based TST is associated with nocturnal BP dipping in healthy men, but not women. This suggests a relation between impaired nocturnal BP regulation and habitual sleep duration, potentially predisposing men to an increased overall risk for cardiovascular complications.

Support (if any)
National Institutes of Health (HL-098676 and HL-122919)
067 Causal Communication Across the Electrode Manifold During Slow Oscillations
Authors: Niknazar Hamid , Malerba Paola , Mednick Sara 
Published: May 2021

Abstract

Introduction
The slow oscillation (0.5-1Hz, SO) is the most studied sleep waveform and reflects sleep homeostasis and is crucial for memory consolidation. It is not clear how SO causally affects brain networks. We used the effective connectivity technique to investigate causal information flow across the electrode manifold during the SO.

Methods
Night sleep EEG signals of 59 adult participants were recorded and visually scored into five sleep stages. We used three EEG channels for each region including frontal, central, parietal, and occipital. SOs were detected automatically and signals from one second before to one second after the SO’s troughs were used for estimating effective connectivity in SO and non-SO windows. Windowing technique and generalized partial directed coherence were employed to estimate causal information flow (CIF) between selected brain regions. The Linear mixed-effect (LME) method was used to model the peaks of the CIF based on different predictors including SO channel, source and sink of CIF, and distance between each of SO channel, source and sink regions.

Results
The results of CIF estimation showed two peaks of CIF about 250ms before and after the SO’s trough, but no difference between CIF in SO’s trough and non-SO windows. We found no effect of source and sink regions, and their distance on CIF (p-value &gt; 0.05). However, distance between SO channel to source and sink region (p-value &lt; 0.05) significantly predicted CIF. The coefficients of the LME model showed a direct effect of distance between SO channel to sink region and opposite effect of distance between SO channel to source region on CIF peaks.

Conclusion
The results showed there were significant changes of brain regions causal communication during SOs and these changes were affected by the distance of SO channel to sink and source region of CIF. Channels that are closer to the SO send more information and regions farther from the SO channel receive more information. Based on the results, we hypothesize that the SO brain networks are optimized to facilitate communication between regions that are far apart.
Support (if any):
069 Chronic pain in Veterans with TBI is associated with decreased EEG slow wave coherence during NREM sleep
Authors: Balba Nadir , Reynolds Christina , Modarres Mo , McBride Alisha , Yildiz Selda , Heinricher Mary , Lim Miranda 
Published: May 2021

Abstract

Introduction
Chronic pain and sleep disturbances are intricately linked to one another, especially in individuals with a history of traumatic brain injury (TBI) who are at greater risk for both symptoms. Although prior studies have analyzed differences in sleep electroencephalogram (EEG) in these clinical populations, the association between sleep EEG slow wave coherence and pain complaints is not fully examined or known. Our novel slow wave coherence approach may provide new insights into the relationship between TBI, chronic pain, and sleep

Methods
Ninety-six veterans were recruited and enrolled under a VA IRB-approved protocol. Participants completed a semi-structured clinical interview to determine their history of TBI, Symptom Impact Questionnaire Revised (SIQR), a measure of chronic pain complaints, and underwent an attended overnight in-lab polysomnogram (PSG). We developed a novel computational signal processing algorithm to identify and quantify EEG slow waves within 100 ms bins across the 6 standard PSG EEG channels. When a slow wave was simultaneously observed in 4 or more of the 6 leads, slow wave coherence was inferred, and a percentage of slow wave coherence across each of the sleep stages was then calculated for each subject.

Results
In our sample, 65 participants (67.7%) endorsed experiencing chronic pain lasting 3 months or longer, and 54 had a history of TBI (56.3%). Participants endorsing chronic pain had a significantly lowered percent of EEG slow wave coherence during NREM sleep than subjects without chronic pain (p = 0.01). NREM EEG slow wave coherence did not correlate with SIQR scores in subjects without TBI (r = -0.03, p = 0.90), but was significantly negatively correlated in subjects with TBI (r = -0.32, p = 0.02).

Conclusion
EEG slow wave coherence during NREM sleep is correlated with chronic pain complaints in Veterans with a history of TBI, and could be indicative of neuronal dysfunction during sleep. Further research on slow wave coherence is warranted to understand the underlying mechanisms for the association between chronic pain and poor sleep following TBI.

Support (if any)
D01 W81XWH-17-1-0423
070 Respiratory, cardiac, EEG, BOLD signals and functional connectivity over multiple microsleep episodes
Authors: Soon Chun Siong , Vinogradova Ksenia , Ong Ju Lynn , Calhoun Vince , Liu Thomas , Zhou Juan Helen , Ng Kwun Kei , Chee Michael 
Published: May 2021

Abstract

Introduction
Brief intrusions of unintended sleep can occur in various contexts, for example during resting-state fMRI scans. In addition to changes in neural activity, such microsleep episodes are also associated with shifts in respiration and heartrate. Here we investigated how these concurrent changes alter the dynamics of the BOLD signal in the brain and estimates of functional connectivity.

Methods
Ten participants underwent 6 runs of 20 minute resting-state fMRI scans with concurrent respiration, PPG and EEG recording. Realtime eye-closure monitoring combined with post eye-opening self-reports were used to identify microsleep episodes of different durations.

Results
During microsleep, sustained reductions were observed in arousal as assessed by EEG (ratio of alpha to delta and theta bands), as expected. In comparison, cortical BOLD signal exhibited more complex, temporally multiphasic changes which were consistent across different microsleep durations from 4 to 44s: (i) an initial sleep-onset dip reaching a nadir after ~6s, followed by (ii) an increase above wake baseline that plateaued till awakening. On awakening, (iii) a transient positive bump occurred up to 6s, followed by (iv) an undershoot below baseline lasting ~30s. While seen across the whole brain, these changes showed regional variations, e.g., the signal plateau in the thalamus remained below wake baseline. Sleep onset and awakening were also associated with respective reductions and increases in respiration and heart rate, which affect blood oxygen levels. Brain functional connectivity estimates were altered by the frequency of falling asleep, and this was not resolved by global signal regression.

Conclusion
Falling asleep and awakening are shown here to be associated with large, widespread BOLD signal changes consistent across varied durations of microsleep. These signal changes are intimately intertwined with shifts in respiration and heart rate, which are influenced by common brainstem nuclei controlling sleep. These autonomic contributions to ‘brain signal’ changes at microsleep onset and awakening are integral to sleep, and urge the integration of autonomic and central nervous system contributions to BOLD signal into frameworks for understanding brain function using fMRI. In addition, the correlation between frequency of microsleep and extent of altered functional connectivity highlight the need to minimize sleep during resting state scans.

Support (if any)
NMRC/STaR/015/2013