bluuebunny/crossref_metadata_2025 huggingface dataset:
119 Behavioral Attention and Sleepiness Display Robust Stable Relationships Across Sleep Loss but not Across Recovery
Authors: Goel Namni , Casale Courtney , Brieva Tess , Antler Caroline , Yamazaki Erika
Published: May 2021

Introduction

The 10-minute and 3-minute versions of the Psychomotor Vigilance Test (PVT10 and PVT3) and the Karolinska Sleepiness Scale (KSS) are commonly used to assess objective behavioral attention deficits and subjective sleepiness in response to sleep loss, respectively. However, the precise time course of relationships between behavioral attention and subjective sleepiness across sleep loss and recovery remains unknown but is critical for determining whether objective and subjective measures track each other. Repeated measures correlation (rmcorr) examined within-individual association between these measures throughout a highly controlled sleep deprivation study.

Methods

Forty-one healthy adults (ages 21-49;mean±SD, 33.9±8.9y;18 females) participated in a 13-night experiment consisting of two baseline nights (10h-12h time-in-bed, TIB) followed by 5 sleep restriction (SR) nights (4h TIB), 4 recovery nights (12h TIB), and 36h total sleep deprivation (TSD). A neurobehavioral test battery, including the PVT10, PVT3, and KSS, was administered every 2h during wakefulness. Rmcorr compared PVT10 [lapses (reaction time [RT] >500ms) and 1/RT (response speed)], PVT3 (lapses [RT>355ms], 1/RT), and KSS scores by examining correlations by day (e.g., Baseline day 2) and time point (e.g., 1000h-2000h). Rmcorr ranges: r=0.1:small; r=0.3:moderate; r=0.5:large.

Results

Generally, the correlations between the PVT10 and KSS and the PVT3 and KSS showed a similar pattern for lapses and 1/RT. PVT lapses and KSS scores showed small or non-significant correlations during baseline and recovery, whereas SR and TSD showed moderate correlations. PVT 1/RT and KSS scores showed moderate correlations during baseline, moderate to large correlations during SR and TSD, but small correlations during recovery. PVT10 and PVT3 1/RT showed stronger correlations with KSS scores than lapses. Additionally, all relationships showed moderate to large correlations by time point across the study.

Conclusion

Overall, the relationship between behavioral attention and sleepiness was stronger across sleep loss (SR or TSD) relative to fully rested states while it was consistently relatively strong at specific times of day throughout the study. In contrast to published literature, there is a remarkably stable relationship between an individual’s objective behavioral attention performance and perceptions of sleepiness during sleep loss, which is not evident during recovery or at baseline.

Support (if any)

ONR Award No. N00014-11-1-0361;NIH UL1TR000003;NASA NNX14AN49G and 80NSSC20K0243;NIH R01DK117488
151 Sex Differences in the Maturational Trajectories of Sleep Spindles in the Transition from Childhood to Adolescence
Authors: Ricci Anna , He Fan , Younes Magdy , Calhoun Susan , Fang Jidong , Houser Lyndsey , Vgontzas Alexandros , Liao Duanping , Bixler Edward , Fernandez-Mendoza Julio
Published: May 2021

Introduction

Sleep spindles occur as bursts of EEG activity in the sigma (11-16 Hz) frequency range and are purported biomarkers of cortical development. However, the few studies examining maturational changes in sleep spindles are limited by small samples and/or short follow-up periods. Thus, large longitudinal population-based studies are needed to determine their developmental trajectories as the child transitions to adolescence.

Methods

We analyzed the sleep EEG of 572 un-medicated subjects aged 6-21 (47.6% female, 25.9% racial/ethnic minority), of whom 332 were 5-12 years at baseline and followed-up at ages 12-22. Multivariable-adjusted models tested the cross-sectional and longitudinal trajectories of sleep spindle density, frequency, and power.

Results

From age 6 to 21, the trajectory of sleep spindle density was best fit by a quadratic model (p=0.02), particularly in males (p-quadratic=0.05). Females maintained more stable levels of sleep spindle density (p-linear=0.26), as shown by a longitudinal increase 37.6% lower than males by age 14 (p=0.01). Sleep spindle frequency increased (p-linear<0.01), while sleep spindle power decreased (p-linear<0.01), from age 6 to 21. The trajectory of sleep spindle frequency diverged between females (p-linear<0.01) and males (p-quadratic=0.02), in whom it plateaued by age 15 onwards. Females had experienced a longitudinal increase in sleep spindle frequency 2.4% higher than males by age 20-22 (p=0.05). Males had experienced a steeper decreasing slope in sleep spindle power (p-linear<0.01) than females (p-linear=0.12), as confirmed by a longitudinal decline 25.4% greater than females by age 19 (p=0.02).

Conclusion

Sleep spindle metrics follow distinct maturational trajectories from each other and from other EEG oscillations (e.g., slow wave activity). The increase in sleep spindle density from childhood to early adolescence coupled with the linear increase in sleep spindle frequency from childhood to young adulthood may represent the emergence of fast sleep spindles, which appears to occur earlier in females. Overall, males experience greater maturational changes in all sleep spindle metrics and sex differences become prominent in young adulthood, when males show lower sleep spindle density and sleep spindle frequency, indicative of less fast sleep spindles.

Support (if any)

NIH Awards Number R01MH118308, R01HL136587, R01HL97165, R01HL63772, UL1TR000127
163 Actigraphy-measured circadian factors and mortality in US adults: Results from the NHANES
Authors: Lin Zhuozhi , Rojo-Wissar Darlynn , Nestadt Paul , Urbanek Jacek , Di Junrui , Zipunnikov Vadim , Spira Adam
Published: May 2021

Introduction

Chronotype is a potentially modifiable contributor to human well-being and longevity, with eveningness commonly linked to poorer outcomes. We examined the relationship between actigraphy-measured chronotype and all-cause mortality in a nationally representative sample of US adults. We also examined the association between social jetlag, a measure of circadian misalignment, and all-cause mortality.

Methods

Data were from 2,256 participants ≥50 from the National Health and Nutrition Examination Survey 2003-2006 cohorts. Participants were asked to wear a hip-worn Actigraph 7164 uni-axial activity monitor for 7 days, and to remove the device for sleep. Objectively-measured bedtime (OBT) was computed as the start of the non-wear period with the longest duration within each 24h period. Duration of the in-bed period (OBT-D) was computed as the hours from OBT to the end of the in-bed period. Midpoint of OBT (OBT-M) was computed as the midpoint between OBT and the end of the in-bed period. Chronotype was estimated using the average OBT-M separately for weekdays, weekends (Friday and Saturday nights), and all days combined. A weekend OBT-M corrected for sleep debt for participants with weekend OBT-D>weekday OBT-D was also computed. The following formula was applied to correct for sleep debt: weekend OBT-M minus ((weekend OBT-D minus weekday OBT-D)/2). Consistent with previous research, OBT-Ms were categorized into intermediate (≥3:30am & ≤4:30am), morningness (<3:30am), and eveningness (>4:30am) chronotypes. Social jetlag was defined as the difference between weekend and weekday OBT-Ms and expressed in hours. Survey-weighted Cox proportional hazard models were used to examine the relationship between circadian factors and all-cause mortality. There were 642 deaths, excluding accidental deaths.

Results

Adjusted for age, sex, race, SES, BMI, smoking and drinking status, comorbidities, and average OBT-D, an eveningness chronotype (i.e., weekend OBT-M corrected for sleep debt) was associated with a greater hazard of death compared to an intermediate chronotype (HR=1.68, 95% CI=1.25, 2.26). There were no other significant associations.

Conclusion

Evening-oriented chronotype is associated with greater mortality risk in adults aged ≥50. To our knowledge, this is the first study to report the link between chronotype, estimated objectively via actigraphy, and all-cause mortality in a nationally representative sample.

Support (if any)

NIH grant 5T32MH014592-39.
173 The Bidirectional Relationships Between Sleep, Psychological Stress, and Negative Mood in Daily Life among Healthy Latinx Adults
Authors: Alcantara Carmela , Giorgio Luciana , Diaz Sarah , Morris Melanie , He Yun , Li Gen , Schwartz Joseph , Basner Robert , Redline Susan , Davidson Karina
Published: May 2021

Introduction

While psychological stress is adversely linked to sleep, the bidirectional and temporal relationships between sleep and psychological stress in the context of daily life are largely understudied, particularly among Latinxs. We examined the bidirectional relationships between daily sleep duration, sleep quality, perceived stress, and negative mood in Latinx adults.

Methods

Between 2016-2019, healthy Latinxs (N=42), defined as those without any major physical or psychiatric morbidities, and free from polysomnography-assessed sleep disorders, were recruited from a community sample in New York. Participants naïve to study hypotheses completed 40 consecutive days of actigraphy and ecological momentary assessment of psychological stress and negative mood (depressed, anxious mood) using a 0 (not at all) to 10 (extremely) scale, contributing 1713 observations. Daily sleep duration was measured via wrist-actigraphy, and perceived daily sleep quality (1[very bad] to 4[very good]) was assessed via morning self-report. Sources of daily stress, including sociocultural stress, were collected once each evening. Multi-level modeling was used to examine within-person effects and temporal associations with adjustment for day of the week.

Results

Mean age=37.2 (SD=11.8), 69.1% women, 36.6% unemployed, 64.3% immigrant, and 38.1% Spanish-speaking. Non-specific stress (43%), work (28%), and family/relationship (21%) stress were the most common sources of daily stress. Discrimination and immigration stress were rarely reported as daily sources of stress (1.2%). Mean nightly sleep duration was 403.9 minutes (±81.3). Preliminary lagged linear mixed models indicated that a 60-minute increase in sleep duration during the night predicted a -.12 change in stress ratings (SE=.001,p<.0001) the next day, as well as -.06 change in anxious mood (SE=.001,p=.003). Better perceived sleep quality on a 4-point scale during the night predicted lower stress ratings (ß=-.11,SE=.05,p=.04) and less anxious mood (ß=-.13,SE=.05,p=.01) the next day. A one-point higher rating of depressed mood during the day predicted a -.03 decrease in perceived sleep quality that night (SE=.01,p<.05).

Conclusion

Overall, these results imply distinct associations of sleep with both anxiety and depressed mood. Longer sleep duration and improved perceived sleep quality were associated with subsequent decreased stress and anxiety. Increased depressed mood predicted worse sleep quality that night. Future research should identify the mechanisms of action for these differential associations.

Support (if any):
190 Changing national trends in sleep and related features among Korean adults between 2009 and 2018
Authors: Yoon Jee-Eun , Kim Daeyoung , Yang Kwang Ik , Chu Min Kyung , Yun Chang-Ho
Published: May 2021

Introduction

Sleep patterns have been linked to various heath disease. Evaluating population-level trend of sleep could provide a comprehensive population health-forecasting model that has the potential to inform targeted interventions. Therefore, we aimed to examine the cross-sectional differences in sleep characteristics among Korean adults during a 9-year period of 2009-2018.

Methods

The data in this study were derived from two nationwide survey regarding sleep and headache in the representative sample of Korean adult population, namely the Korean Sleep Headache Study phase I (2009) and II (2018). The survey was conducted through door-to-door visit and face-to-face interview by using structured questionnaires. Total of 2,836 participants from Phase I (47.9±16.4 years old; female, 50.2%) and 2,501 participants (47.9±16.4 years old; female, 50.3%) from Phase II gave informed consents and completed the survey. For this study, we excluded those who worked as shift workers and missing data. From the MCTQ, we collected participants’ sleep schedule during workdays and free days over the past four weeks. Average sleep duration was a weighted mean of sleep duration on workdays and free days. Poor sleep quality was defined as PSQI >5. Excessive daytime sleepiness and Depression are performed with ESS and PHQ-9, respectively.

Results

During the 9 years, average sleep duration decreased by 21 minutes, especially more reduction on free days (workday: 7:17±1:58 vs. 7:06±1:06, p <0.001; free days 8:04±2:32 vs. 7:49±1:23, p <0.001). People go to sleep and wake up earlier on workday (workday 23:39±1:50 vs. 23:25±1:30, p <0.001; free days 23:51±2:11 vs. 23:25±2:11, p <0.001), whereas they go to bed earlier and wake up later on free days compared to past (workday 6:52±1:36 vs. 6:37±1:11, p <0.001; 7:42±2:04 vs. 7:49±1:42 p =0.023). Social jetlag was increased by 5 minutes (0:46±1:35 vs. 0:51±0:52, p =0.028). There was the difference of age on the habitual sleep-wake rhythm and sleep related symptoms. Also, short or long sleep duration was associated with a significant increase in each health outcomes.

Conclusion

Decreased sleep duration seems to be on the rise in the general adult population, which lead to a poor health status. Interventions to promote adequate sleep is urgently needed.

Support (if any):
206 Changes in Sleep Due to the COVID Pandemic Associated with Sleep Environment
Authors: Holbert Cameron , Kennedy Kathryn , Killgore William , Wills Chloe , Grandner Michael
Published: May 2021

Introduction

The COVID-19 pandemic has resulted in adverse impacts on sleep for many people. The physical environment has been a focus for health-related behaviors during the pandemic since movement restrictions have led to a heightened awareness of the living environment. This study examined whether those whose physical environment was more disruptive to sleep systematically experienced more pandemic-related sleep problems.

Methods

A sample of N=419 US adults completed online surveys (mostly during the summer months) about sleep and COVID-19 experiences. Participants were asked the degree to which they endorsed statements that due to the pandemic, (1) they were able to keep a regular schedule, (2) they had more problems falling asleep, (3) they had more problems with nighttime awakenings, (4) they experienced more daytime sleepiness, and (5) they napped more. Sleep environment was assessed using the Assessment of Sleep Environment (ASE), a 13-item questionnaire that quantifies the degree to which sleep is disrupted environmental influences (scores range from 0-39). Ordinal logistic regression analyses, with degree of agreement with statements about changing sleep due to the pandemic as outcome, ASE score as independent variable, and age and sex as covariates.

Results

Worse sleep environment was associated with a decreased likelihood of being able to keep a regular schedule (oOR=0.96, p<0.04) and an increased likelihood of more problems falling asleep (oOR=1.04, p<0.02), problems with nighttime awakenings (oOR=1.03, p<0.02), daytime sleepiness (oOR=1.03, p<0.03), and napping (oOR=1.03, p<0.04). Post-hoc analyses examine contributions of individual items, and the one that was independently most associated with changes in sleep was sleeping environment being too warm.

Conclusion

Those with a more disruptive sleep environment experienced a greater degree of problematic sleep problems as a result of the COVID-19 pandemic. The fact that these assessments largely took place in warmer months may explain why sleeping environments being “too warm” was especially salient.

Support (if any)

R01MD011600, R01DA051321
210 Changes in Dream Recall During the COVID-19 Pandemic: Associations with Sleep, Stress and Dream Content
Authors: Wills Chloe , Kennedy Kathryn , Bastien Célyne , Ruby Perrine , Killgore William D S , Grandner Michael
Published: May 2021

Introduction

During the COVID-19 pandemic, individuals have faced unprecedented events, which are often stressful. Stress has an important impact on dreams, and stress-induced sleep difficulties may also impact dream recall. The present study evaluated associations between sleep, stress and dream content on dream recall during the pandemic.

Methods

A sample of N=419 US adults completed online surveys about sleep and COVID-19 experiences. Participants were asked if they remember more, fewer or about the same amount of dreams as before the pandemic. They were also asked whether the pandemic was associated with more stress, a more regular schedule, improved sleep, worse sleep, more early insomnia, more middle-of-the-night insomnia, more sleepiness, and more naps. They also completed the Insomnia Severity Index, Fatigue Severity Scale, Epworth Sleepiness Scale, Brief Index of Sleep Control, Assessment of Sleep Environment, GAD-7 anxiety scale, and PHQ9 depression scale. Multinomial logistic regressions examined correlates of increased or decreased recall (versus same), adjusted for age, sex, and race/ethnicity.

Results

Those who experienced greater schedule regularity were less likely to report decreased recall (RRR=0.50,p<0.0005), as were those who reported sleep improvement (RRR=0.48,p=0.006). Those whose sleep worsened were more likely to report both increased (RRR=1.64,p=0.003) and decreased (RRR=2.16,p<0.0005) recall. Those suffering maintenance insomnia were more likely to report both increased (RRR=1.70,p=0.001) and decreased (RRR=2.68,p<0.0005) recall, as did those who reported more daytime sleepiness (Increased RRR=1.57,p=0.006; Decreased RRR=1.94,p=0.001). Those whose dream content was more negative were more likely to report both increased (RRR=4.05,p<0.005) and decreased (RRR=3.35,p<0.0005) recall, as did those who reported less negative content (Increased RRR=4.20,p<0.0005; Decreased RRR=5.05,p<0.0005). Similarly, those who reported more positive dream content reported both increased (RRR=17.37,p<0.0005) and decreased (RRR=7.14,p=0.02) recall, as did those who reported less positive content (Increased RRR=4.49,p<0.0005; Decreased RRR=5.59,p<0.0005). Less recall was associated with greater insomnia severity (RRR=1.08,p=0.001), fatigue (RRR=1.04,p=0.001), sleepiness (RRR=1.09,p=0.01), COVID stress (RRR=1.67,p=0.03), anxiety (RRR=1.08,p=0.01), and depression (RRR=1.06,p=0.007), worse sleep environment (RRR=1.06,p=0.005), and less sleep control (RRR=0.56,p=0.001).

Conclusion

The results of this survey suggest that a sudden decrease in dream recall in reaction to a new stress could be considered as a pejorative indicator regarding sleep quality and mental health.

Support (if any)

R01MD011600, R01DA051321
214 Longitudinal Changes in Sleep Duration, Timing, Variability, and Stages during the COVID-19 Pandemic: Large-Scale Fitbit Data
Authors: Grandner Michael , Rezaei Naghmeh
Published: May 2021

Introduction

The COVID-19 pandemic has resulted in societal-level changes to sleep and other behavioral patterns. Objective, longitudinal data would allow for a greater understanding of sleep-related changes at the population level.

Methods

N= 163,524 deidentified active Fitbit users from 6 major US cities contributed data, representing areas particularly hard-hit by the pandemic (Chicago, Houston, Los Angeles, New York, San Francisco, and Miami). Sleep variables extracted include nightly and weekly mean sleep duration and bedtime, variability (standard deviation) of sleep duration and bedtime, and estimated arousals and sleep stages. Deviation from similar timeframes in 2019 were examined. All analyses were performed in Python.

Results

These data detail how sleep duration and timing changed longitudinally, stratified by age group and gender, relative to previous years’ data. Overall, 2020 represented a significant departure for all age groups and both men and women (P<0.00001). Mean sleep duration increased in nearly all groups (P<0.00001) by 5-11 minutes, compared to a mean decrease of 5-8 minutes seen over the same period in 2019. Categorically, sleep duration increased for some and decreased for others, but more extended than restricted. Sleep phase shifted later for nearly all groups (p<0.00001). Categorically, bedtime was delayed for some and advanced for others, though more delayed than advanced. Duration and bedtime variability decreased, owing largely to decreased weekday-weekend differences. WASO increased, REM% increased, and Deep% decreased. Additional analyses show stratified, longitudinal changes to sleep duration and timing mean and variability distributions by month, as well as effect sizes and correlations to other outcomes.

Conclusion

The pandemic was associated with increased sleep duration on average, in contrast to 2019 when sleep decreased. The increase was most profound among younger adults, especially women. The youngest adults also experienced the greatest bedtime delay, in line with extensive school-start-times and chronotype data. When given the opportunity, the difference between weekdays and weekends became smaller, with occupational implications. Sleep staging data showed that slightly extending sleep minimally impacted deep sleep but resulted in a proportional increase in REM. Wakefulness during the night also increased, suggesting increased arousal despite greater sleep duration.

Support (if any)

This research was supported by Fitbit, Inc.
225 Sleep Timing and Chronotype in Mothers: Longitudinal Changes and Associations with Wellbeing from Pregnancy to 2 Years Postpartum
Authors: Verma Sumedha , Pinnington Donna , Manber Rachel , Bei Bei
Published: May 2021

Introduction

Women experience significant changes to sleep during perinatal periods. Existing research focuses on sleep duration and quality, but not sleep timing or chronotype (i.e., preferred timing for activity and sleep). This study investigated change trajectories of sleep timing and chronotype from late pregnancy to two years postpartum, and examined longitudinal associations between chronotype and insomnia, sleep-related daytime impairment, and mood.

Methods

Data were from a 2-arm randomized controlled trial testing behavioral sleep and diet interventions. A community sample of nulliparous women without severe sleep/mental health conditions participated. Women self-reported bedtime, risetime, chronotype (reduced Morningness-Eveningness Questionnaire), Insomnia Severity Index, and PROMIS Depression, Anxiety, and Sleep-Related Impairment over 7 time points: 30 and 35 weeks’ gestation, and postpartum months 1.5, 3, 6, 12 and 24.

Results

163 women (mean age 33.35 ± 3.42 years) took part. Mixed effects models controlling for age and group allocation showed that both bed- and risetimes became progressively earlier over time by approximately 20-30 minutes on average (p < .001); chronotype also shifted progressively towards morningness (p < .01). After controlling for covariates (sleep duration and efficiency, mental health history, social support, age, group allocation), greater morningness was significantly associated with lower symptoms of insomnia and sleep-related impairment over time (p-values < .001); longitudinal associations between chronotype and symptoms of depression and anxiety were non-significant (p-values > .65).

Conclusion

This is one of the first studies to examine longitudinal changes in sleep timing and chronotype from pregnancy to two years postpartum. Sleep timing and chronotype became progressively earlier over the first two postpartum years. The magnitude of changes is beyond what is expected with increasing age. Greater morningness was associated with lower sleep complaints and sleep-related daytime impairment during the postpartum period. The mechanisms underlying these associations require further research.

Support (if any)

Australasian Sleep Association, Monash University, Australian Government RTP Scholarship and National Health and Medical Research Council.
237 Sleep disturbances, online instruction, and learning during COVID-19: evidence from 4148 adolescents in the NESTED study
Authors: Saletin Jared , Owens Judith , Wahlstrom Kyla , Honaker Sarah , Wolfson Amy , Seixas Azizi , Wong Patricia , Carskadon Mary , Meltzer Lisa
Published: May 2021

Introduction

COVID-19 fundamentally altered education in the United States. A variety of in-person, hybrid, and online instruction formats took hold in Fall 2020 as schools reopened. The Nationwide Education and School in TEens During COVID (NESTED) study assessed how these changes impacted sleep. Here we examined how instruction format was associated with sleep disruption and learning outcomes.

Methods

Data from 4148 grade 6-12 students were included in the current analyses (61% non-male; 34% non-white; 13% middle-school). Each student’s instructional format was categorized as: (i) in-person; (ii) hybrid [≥1 day/week in-person]; (iii) online/synchronous (scheduled classes); (iv) online/asynchronous (unscheduled classes); (v) online-mixed; or (vi) no-school. Sleep disturbances (i.e., difficulty falling/staying asleep) were measured with validated PROMIS t-scores. A bootstrapped structural equation model examined how instructional format and sleep disturbances predict school/learning success (SLS), a latent variable loading onto 3 outcomes: (i) school engagement (ii) likert-rated school stress; and (iii) cognitive function (PROMIS t-scores). The model covaried for gender, race-ethnicity, and school-level

Results

Our model fit well (RMSEA=.041). Examining total effects (direct + indirect), online and hybrid instruction were associated with lower SLS (b’s:-.06 to -.26; p’s<.01). The three online groups had the strongest effects (synchronous: b=-.15; 95%CI: [-.20, -.11]; asynchronous: b=-.17; [-.23, -.11]; mixed: b=-.14; [-.19, -.098]; p’s<.001). Sleep disturbance was also negatively associated with SLS (b=-.02; [-.02, -.02], p<.001). Monte-carlo simulations confirmed sleep disturbance mediated online instruction’s influence on SLS. The strongest effect was found for asynchronous instruction, with sleep disturbance mediating 24% of its effect (b = -.042; [-0.065, -.019]; p<.001). This sleep-mediated influence of asynchronous instruction propagated down to each SLS measure (p’s<.001), including a near 3-point difference on PROMIS cognitive scores (b = -2.86; [-3.73, -2.00]).

Conclusion

These analyses from the NESTED study indicate that sleep disruption may be one mechanism through which online instruction impacted learning during the pandemic. Sleep disturbances were unexpectedly influential for unscheduled instruction (i.e., asynchronous). Future analyses will examine specific sleep parameters (e.g., timing) and whether sleep’s influence differs in teens who self-report learning/behavior problems (e.g., ADHD). These nationwide data further underscore the importance of considering sleep as educators and policy makers determine school schedules.

Support (if any):
252 Non-Invasive Quantification of Human Brain Lactate Concentrations Across Sleep-Wake Cycles
Authors: Yildiz Selda , Lim Miranda , Sammi Manoj , Powers Katherine , Murchison Charles , Iliff Jeffrey , Rooney William
Published: May 2021

Introduction

Cellular mechanisms underlying changes in small animal brain lactate concentrations have been investigated for more than 70 years and report sharp reductions in lactate (12-35%) during sleep or anesthesia relative to wakefulness. The goal of this study was to investigate alterations in human cerebral lactate concentrations across sleep-wake cycles. Toward this goal, we developed a novel non-invasive methodology, quantified changes in human cerebral lactate during sleep stages, and investigated potential mechanisms associated with changes in lactate.

Methods

Nine subjects (four females, five males; 21-27 y-o, mean age 24.2 ±2) were sleep deprived overnight, and underwent (5:45~11:00 am) experiments combining simultaneous MR-spectroscopy (MRS) and polysomnography (PSG) in a 3 T MR instrument using a 64-channel head/neck coil. A single voxel MRS (1H-MRS) acquired signals from a volume of interest (12~24 cm3) for every 7.5-s for 88~180-min. Lactate signal intensity was determined from each 7.5-s spectrum, normalized to corresponding water signal, and averaged over 30-s for each PSG epochs. Artifact corrected PSG data were scored for each 30-s epoch using the standard criteria and classified into one of four stages: W, N1, N2 and N3. Group mean lactate levels were quantified using LCModel. Three subjects returned for lactate diffusivity measurements using diffusion-sensitized PRESS MRS sequence.

Results

Compared to W, group mean lactate levels within each sleep stage showed a reduction of [4.9 ± 4.9] % in N1, [10.4 ± 5.2] % in N2, and [24.0 ± 5.8] % in N3. We observed a significant decrease in lactate apparent diffusion coefficient (ADC) accompanied by reduced brain lactate in sleep compared to wake (P<0.002). There were no differences in ADC values between wake and sleep for H2O, NAA, tCr, or Cho.

Conclusion

This is the first in-vivo report of alterations in human brain lactate concentrations across sleep-wake cycles. Observed decline in lactate levels during sleep compared to wakefulness is consistent with, and extends results from invasive small animal brain studies first reported more than 70 years ago, and support the notion of altered lactate metabolism and/or increased glymphatic activity in sleeping human brain.

Support (if any)

The Paul. G. Allen Family Foundation funded the study.
260 Beyond Validation Testing: A Sleep Tracker for Longitudinal Data Collection in Operational Environments
Authors: Devine Jaime , Chinoy Evan , Markwald Rachel , Devine Jaime , Hursh Steven
Published: May 2021

Introduction

Sleep tracking wearables are increasingly being validation tested against polysomnography (PSG) and actigraphy, but they may not be ideal for long-term epidemiological sleep studies, or for use in operational environments. A given device’s short battery life, limited data storage capacity, inability to detect naps or estimate sleep architecture, or privacy concerns may discourage researchers from using wearables to collect objective sleep data in real-world settings. The Zulu watch (Institutes for Behavior Resources) is designed to collect longitudinal sleep data in operational populations with irregular sleep patterns, such as long-haul pilots or shift workers. It is capable of on-wrist sleep-wake determination, nap detection, on-wrist sleep depth scoring (i.e., interrupted sleep, light sleep, or deep sleep), on-wrist data storage up to 80 sleep intervals, and year-long battery life. Laboratory testing is an important initial step toward establishing the performance of a device for longitudinal real-world sleep evaluation; therefore, the Zulu watch sleep tracking was subjected to testing against gold-standard PSG and actigraphy.

Methods

Eight healthy young adult participants (30.4±3.2 years; mean±SD) wore a Zulu watch and Philips Respironics Actiwatch 2 simultaneously over a 3-day laboratory PSG sleep study, with 8 hours time-in-bed each night. Overall epoch-by-epoch agreement of sensitivity (for sleep), specificity (for wake), and accuracy of Zulu watch data were tested against PSG and Actiwatch 2.

Results

Compared with either PSG or actigraphy, both accuracy and sensitivity for Zulu watch sleep-wake determination were >90% while specificity was low (~26% vs. PSG, ~33% vs. actigraphy). Accuracy for sleep scoring vs. PSG was ~87% for interrupted sleep, ~52% for light sleep, and ~49% for deep sleep.

Conclusion

The Zulu watch showed mixed results but may be a viable candidate for sleep evaluation based on initial laboratory performance testing in healthy adults. The next steps will be to compare the Zulu watch against self-report of sleep in operational and substance use disorder populations. Longitudinal epidemiological sleep studies can become more feasible if technology is tailored to the specific needs of the real-world environment.

Support (if any)

Medical Technology Enterprise Consortium award MTEC-17-08-Multi-Topic-0104; Office of Naval Research, Code 34.
280 Is blue-enriched light more effective than red light to enhance vigilance and cognitive performance in Parkinson’s Disease?
Authors: Rosinvil Thaïna , Daneault Veronique , Vanderwalle Gilles , Desaultels Alex , Forcier Pierre , Gaudet-Fex Benjamin , Apinis-Deshaies Amélie , Aumont Tomy , Constantin Ioana Medeleine , Matute Andrea , Gagnon Jean-Francois , Gosselin Nadia , Lina Jean-Marc , Carrier Julie
Published: May 2021

Introduction

Approximately 50% (between 16–74%) of adults with Parkinson’s disease (PD) show excessive daytime sleepiness. Besides its important role for vision, light conveys a powerful stimulating signal for alertness and cognition. Recent research has demonstrated that the blue part of light spectrum is the most efficient in enhancing vigilance and cognitive performance in young and older healthy individuals, thanks to a specific photoreception system within the eye which is particularly sensitive to blue wavelength. The aim of this pilot study was to compare the effects of blue-enriched light exposure (BL) and red-light placebo exposure (RL) on psychomotor vigilance and cognitive performance in adults with PD.

Methods

Sixteen participants with idiopathic PD (64.0±5.5 yrs, 6 women, Hoehn and Yahr status: 2) completed a brief neuropsychological assessment to exclude dementia, self-reported questionnaires and a complete eye examination in screening visits. The one-day experimental procedure included 1.25 h period of baseline dim-light exposition, followed by two light conditions presented in a counterbalanced design and separated by 15 minutes in dim-light: 1.25 h of BL at 959lux and 1.25 h of placebo RL condition at 472lux. Both light conditions were delivered by Luminette®. Data were normalized according to baseline dim-light evaluation. Mixed analyses of variance (2 light conditions X 2 orders) were performed to compare performance on an auditory psychomotor vigilance task (A-PVT) and an auditory 2-back cognitive tasks (A-2-back) during light exposure.

Results

We observed no significant effect of light conditions, orders and no interaction on reaction time (RT) and number of correct answers for the A-2-Back task. Furthermore, there was no significant difference between BL and RL on A-PVT performance including median RT, shift in optimum RT (i.e.,mean RT from fastest 10% RT), and duration of response in the lapse domain (i.e.,mean RT from slowest 10% RT).

Conclusion

These preliminary results do not support the notion that blue-enriched white light exposure is more efficient than red light exposure to stimulate psychomotor vigilance and cognitive performance in adults with PD. Next steps of analyses will compare the effects of BL and RL on subjective sleepiness and EEG cortical activation in the same population.

Support (if any)

CIHC & QPN
284 Cognitive Deficits due to Insufficient Sleep are Mitigated Following Strenuous Physical Exertion in Firefighters
Authors: Stepan Michelle , Wilckens Kristine , Hostler Dave , Franzen Peter
Published: May 2021

Introduction

Insufficient sleep impairs cognitive function which results in costly errors. Firefighter shifts regularly exceed 24-hrs with little to no sleep. Nevertheless, firefighters must maintain and flexibly shift attention in high-pressure scenarios. Firefighters also engage in strenuous physical exertion during fire suppression activities. However, it is unclear whether physical exertion acts as another stressor, exasperating cognitive deficits due to insufficient sleep, or whether physical exertion enhances arousal to reduce cognitive deficits. Moreover, the effects of physical exertion may depend on the type of cognitive process and extent of sleep loss. We examined the effect of physical exertion on vigilant attention and task-switching in firefighters who underwent sleep-deprivation or sleep-disruption.

Methods

Participants were 17 healthy young adult males who participated in a within-subjects crossover design with three experimental lab visits: sleep-deprivation, sleep-disruption (woken 3 times for 60-min each), and normal sleep. The next day, participants completed a 50-min treadmill exercise task in a heated room in firefighter protective clothing. Participants completed a vigilant attention task (Psychomotor Vigilance Task, PVT) and a task-switching task five to nine times each visit. The five timepoints of interest–before and after the sleep manipulation night, before and after the treadmill exercise task, and recovery (approximately 180-min following exercise)–were examined using linear mixed effects models.

Results

We analyzed lapses (reaction times [RT]>500ms) on the PVT and switch-trial RT and accuracy on the task-switching task for sleep-deprivation and sleep-disruption conditions relative to normal sleep. Sleep-disruption, p=.001, and sleep-deprivation, p<.001, increased lapses. Sleep-disruption increased switch-trial RT, p=.01, and sleep-deprivation reduced switch-trial accuracy, p=.01. Only switch-trial accuracy improved immediately after the treadmill exercise task and only for the sleep-deprivation condition, p=.01. During recovery, lapses lessened for the sleep-deprivation condition, p=.049, and switch-trial accuracy improved for both sleep-deprivation, p=.01, and sleep-disruption conditions, p=.049.

Conclusion

Physical exertion reduced task-switching and attentional deficits caused by insufficient sleep, with more benefits observed during recovery. We found no evidence for performance decrements due to physical exertion. Physical exertion may interact with the extent of sleep loss–primarily benefitting performance under conditions of total sleep-deprivation.

Support (if any)

DSF Charitable Foundation and University of Pittsburgh Clinical and Translational Science Institute UL1TR001857.
286 Pilot Sleep During Brazil-to-China COVID-19 Humanitarian Mission Flights Compared to Biomathematical Predictions of Sleep
Authors: Devine Jaime , Garcia Caio , Simoes Audrey , Choynowski Jake , Guelere Marina , de Godoy Bruno , Pacheco Philipe , Hursh Steven
Published: May 2021

Introduction

n response to the COVID-19 pandemic, Azul Airlines organized and conducted five separate humanitarian missions to China between May and July, 2020. Each mission consisted of 4 flight legs between 11-15 hours long crewed by a team of 8 pilots. Each pilot was given a 9-hour sleep opportunity during the flight period. Prior to conducting the missions, a sleep-prediction algorithm (AutoSleep) within the Sleep, Activity, Fatigue, and Task Effectiveness (SAFTE) model Fatigue Avoidance Scheduling Tool (FAST) was used to predict in-flight time in bed (TIB) and total sleep time (TST). During missions, pilots wore a wrist actigraph and completed a sleep diary. These analyses compare the accuracy of SAFTE-FAST AutoSleep predictions against pilots’ sleep diary and actigraphy from Azul’s COVID-19 humanitarian missions.

Methods

Pilots wore a sleep-tracking actigraphy device (Zulu Watch, Institutes for Behavior Resources), and reported the TIB and sleep quality of their in-flight rest periods using a sleep diary. Diary TST was estimated from TIB and sleep quality. AutoSleep, diary, and actigraphy measures were compared using paired samples t-tests. Agreement was compared using intraclass correlation coefficients (ICC).

Results

Twenty (n=20) pilots flying across 5 humanitarian missions provided sleep diary and actigraphy data. AutoSleep predictions of TIB (235±20 minutes) and TST (193±16 minutes) were significantly lower than diary (TIB: 330±123, t=6.80, p≤0.001; TST: 262±108, t=5.60, p≤0.001) and comparable to actigraphy (TIB: 246±127, t=0.78, p=0.43; TST: 212±113, t=1.59, p=0.12). ICC values were >0.90, indicating excellent agreement, for TIB (0.94) and TST (0.91).

Conclusion

Biomathematical predictions of in-flight sleep during unprecedented humanitarian missions were in agreement with actual sleep patterns during flights. These findings indicate that biomathematical models may retain accuracy even under extreme circumstances like the COVID-19 pandemic. Pilots may overestimate the amount of sleep that they receive during extreme flights-duty periods, which could constitute a fatigue risk.

Support (if any)

NA
304 The relationship between basic personality, subjective sleep duration, and psychological distress during a military deployment
Authors: Sowden Walter , Bessey Alexxa , Merrill Julie , Mckeon Ashlee , Choynowski Jake , Mantua Janna
Published: May 2021

Introduction

Extended, overseas operations (deployments) increase the likelihood that military personnel will experience psychological distress. Reduced sleep during deployments is a key correlate of psychological distress. Thus, it is imperative to identify mechanisms that adaptively modulate the relationship between insufficient sleep and psychological distress. Research has recently connected basic personality traits (i.e., the Big Five: extraversion, agreeableness, conscientiousness, neuroticism, and openness) to more sleep. The current project aimed to examine the relationship between basic personality traits, subjective sleep duration (SSD), and psychological distress during an operational deployment.

Methods

488 soldiers took surveys both prior to and half-way through a nine-month deployment. The pre-deployment survey included the Big Five Index, and three standardized measures of psychological distress commonly used to screen military personnel for anxiety (Generalized Anxiety Disorder; GAD-7), depression (Patient Health Questionnaire; PHQ-8), and post-traumatic stress (Posttraumatic Symptom Disorder Checklist; PCL-4). The mid-deployment survey included an item from the Pittsburgh Sleep Quality Index measuring SSD and the same psychological distress measures from the pre-deployment survey. General linear models were used to test the interaction between SSD and each basic personality trait on each measure of psychological distress at mid-deployment while accounting for psychological distress at pre-deployment.

Results

Of the Big Five, conscientiousness was the only trait to significantly moderate the relationship between SSD and anxiety, t = 2.11, p = .035, where higher conscientiousness weakened the relationship. Further only agreeableness attenuated the relationship between depression and SSD, t = 2.10, p = .036. Interestingly, the only Big Five trait that moderated the relationship between SSD and PTS was openness, insomuch that openness strengthened the relationship, t = -1.92, p = .055.

Conclusion

The relationship between SSD and psychological distress was uniquely impacted by different personality traits. These results reinforce the age-old concept that behavior is the product of a complex, nuanced, and puzzling interaction between the individual and the environment. The current research motivates further research into personality as an adaptive mechanism for optimizing military wellbeing.

Support (if any)

Support for this study came from the Military Operational Medicine Research Program (MOMRP) of the United States Army Medical Research and Development Command (USAMRDC).
309 Food consumption and meal timing in hospital nurses with shift work: A preliminary study
Authors: Kim Jee Hyun
Published: May 2021

Introduction

One of the important nonphotic zeitgebers is food consumption. The timing of food consumption in relation to melatonin onset has been reported to be associated with fat proportion and BMI. Irregular meal timing along with irregular sleep schedules due to shift work would increase the metabolism problem as well as influencing sleep problems. The aim of the study is to evaluate the meal timing and food consumption in shift workers.

Methods

The nurses with 3-rapid rotating shifts were enrolled to keep food diaries for two weeks including all three shift schedules. They filled out a morningness-eveningness questionnaire. They wore actigraphy to monitor sleep-wake patterns with a daily sleep diary. The timing and the frequencies of meal/snack and caffeine consumption during each shift and day-off were reviewed. The calorie from each food was calculated depending on the nutritional information on the internet.

Results

13 female nurses were screened and 6 finished the study. The mean age is 29.4±7.69 years and the mean body mass index was 20.2±1.1kg/m2. Average frequencies of meals are 2.59±0.49, 1.66±0.75, 1.93±0.41, 2.09±0.96 times per day, and average frequencies of snack consumption are 1.37±0.9, 1.07±0.74, 0.75±0.82, 0.96±0.79 times per day for the morning, evening, night, and the day off, respectively. Total calorie consumed are 1662.5±564.8, 1380.8 ± 940.3, 1596.8±838.1, 1505.8±706.9 kcals in the same order. Caffeine consumption was 0.29±0.46, 0.4±0.48, 0.72±0.65, 0.46±0.54 cups per day in the same order. One subject with morning type showed a relatively regular meal schedule throughout the shifts. The timing for main calorie consumption seemed to show delayed on evening and night shifts than morning shift although total calorie consumption was similar between each shift.

Conclusion

Although this is a preliminary study with a small number of subjects, it showed shift worker nurses have an inconsistent number of meals and calorie intake depending on their shifts. Caffeine consumption is very lower than expected. The subject with morning chronotype seemed to keep relatively regular meal timing throughout the shifts, suggesting chronotype influences meal timing in shift workers.

Support (if any)

This study was supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIT) (No.2019R1A2C1090643).
310 Outcomes of a Sleep and Stress-Focused Employee Wellness Program
Authors: Carter Patricia , Eyer Josh , Horton Abby , MacVicar Carolyn
Published: May 2021

Introduction

The Sleep More, Stress Less Program (SMSL) is a University of Alabama (UA) employee wellness program designed to help participants implement health behavior changes to improve sleep quality and stress management. Workplace wellness programs offer a win-win for the employee and employer through improved health and reduced absenteeism. However, many programs fail to show effectiveness on health and workplace metrics, even with an increase in targeted health behaviors. This may be due—at least in part—to employee self-selection and data collection limitations. The SMSL program addresses these challenges by recruiting employees experiencing sleep and stress issues and using a rigorous assessment approach that records data on behavior changes, process goals, intermediate mechanisms, and health outcomes. We present findings from the SMSL program evaluation conducted Fall 2020.

Methods

The SMSL program is delivered online with both synchronous and asynchronous content (videos and exercises). The content combines evidence-based interventions for sleep and stress with the science of behavioral motivation. All adult (19–99 years) UA employees were eligible and recruitment occurred through the WellBama website and employee emails. Employees are encouraged to select programs that match their health issues. Participants complete an online pre-program assessment and track their sleep and stress for one week. Next, participants complete the SMSL educational program over the next three weeks. In the fifth week, participants track their sleep and stress and complete the online post-program assessment.

Results

60 of the initial 85 participants completed all assessments (70.5%). Participants were primarily Female (79%) and Caucasian (77%) or Black (15%), and aged 24–68 (m=44) years. Moderate improvements were reported in total sleep time, sleep maintenance, and time to return to sleep after awakening. Similar improvements were observed in stress scores. Qualitative evaluation of participant behavior goals revealed a focus on sleep scheduling, stimulus reduction, and relaxation.

Conclusion

Employee wellness program evaluation is often affected by selection and measurement bias. The SMSL program targeted individuals experiencing stress and/or sleep problems and measured multiple outcomes to identify benefits over the 5-week program. Other wellness programs would benefit from this approach in order to capture true program outcomes.

Support (if any)

N/A