Sleep Regularity Research Articles

Sleep regularity in a Brazilian population-based sample: findings from the EPISONO study

Sleep regularity in a Brazilian population-based sample: findings from the EPISONO study

Association of the Sleep Regularity Index With Incident Dementia and Brain Volume.

Irregular sleep may increase the risk of cardiometabolic conditions, but its association with incident dementia is unclear. The aim of this study was to assess the association between sleep regularity, that is, the day-to-day consistency in sleep-wake patterns and the risk of incident dementia and related brain MRI endophenotypes. We used Cox proportional hazard models to investigate the relationships between sleep regularity and incident dementia in 88,094 UK Biobank participants. The sleep regularity index (SRI) was calculated as the probability of being in the same state (asleep/awake) at any 2 time points 24 hours apart, averaged over 7 days of accelerometry. The mean age of the sample was 62 years (SD = 8), 56% were women, and the median SRI was 60 (SD = 10). There were 480 cases of incident dementia over a median 7.2 years of follow-up. Following adjustments for demographic, clinical, and genetic confounders (APOE ε4), there was a nonlinear association between the SRI and dementia hazard (p [global test of spline term] < 0.001) with hazard ratios (HRs) following a U-shape pattern. HRs, relative to the median SRI, were 1.53 (95% CI 1.24-1.89) for participants with SRI at the 5th percentile (SRI = 41) and 1.16 (95% CI 0.89-1.50) for those with SRI at the 95th percentile (SRI = 71). In a subset with brain MRI (n = 15,263), gray matter and hippocampal volume tended to be lowest at the extremes of the SRI. Sleep regularity displayed a U-shaped association with risk of incident dementia. Irregular sleep may represent a novel dementia risk factor.

The interrelationships between sleep regularity, obstructive sleep apnea, and hypertension in a middle-aged community population.

Little is known about the interrelationships between sleep regularity, obstructive sleep apnea (OSA) and important health markers. This study examined whether irregular sleep is associated with OSA and hypertension, and if this modifies the known association between OSA and hypertension. Six hundred and two adults (age mean(SD) = 56.96(5.51) years, female = 60%) from the Raine Study who were not evening or night shift workers were assessed for OSA (in-laboratory polysomnography; apnea-hypopnea index ≥ 15 events/hour), hypertension (doctor diagnosed, or systolic blood pressure ≥140 mmHg and/or diastolic ≥90 mmHg) and sleep (wrist actigraphy for ≥5 days). A sleep regularity index (SRI) was determined from actigraphy. Participants were categorized by tertiles as severely irregular, mildly irregular, or regular sleepers. Logistic regression models examined the interrelationships between SRI, OSA and hypertension. Covariates included age, sex, body mass index, actigraphy sleep duration, insomnia, depression, activity, alcohol, smoking, and antihypertensive medication. Compared to regular sleepers, participants with mildly irregular (OR 1.97, 95% confidence intervals [CI] 1.20 to 3.27) and severely irregular (OR 2.06, 95% CI: 1.25 to 3.42) sleep had greater odds of OSA. Compared to those with no OSA and regular sleep, OSA and severely irregular sleep combined had the highest odds of hypertension (OR 2.34 95% CI: 1.07 to 5.12; p for interaction = 0.02) while those with OSA and regular/mildly irregular sleep were not at increased risk (p for interaction = 0.20). Sleep irregularity may be an important modifiable target for hypertension among those with OSA.

Regularity of bedtime, wake-up time, and time in bed in mid-life: associations with cardiometabolic health markers with adjustment for physical activity and sedentary time

BackgroundInsufficient sleep has been linked to the accumulation of cardiometabolic risks while physical activity acts as a protective factor. Also, sleep regularity may play a critical role in maintaining optimal cardiometabolic health. This cross-sectional study examined the association between device-based sleep regularity, waking activity behaviors, and cardiometabolic health markers, including blood pressure level; abdominal adiposity level; and blood glucose, insulin, and cholesterol.MethodsWe included 3698 members of the Northern Finland Birth cohort 1966 who participated in the follow-up study at the age of 46 years between 2012 and 2014 (women 61%). We used seven-day standard deviations of device-based bedtime, wake-up time, and time in bed to reflect sleep regularities. As covariates in linear regression models, we used commonly known potential risk factors in (gender, education, marital status, work schedule, smoking status, alcohol risk use, seven-day time in bed mean, chronotype). In addition to the previous, we used either sedentary time or total physical activity as a covariate (B coefficients with 95% confidence intervals CI).ResultsWhen we considered sedentary time with other covariates, irregularities in bedtime, wake-up time, and time in bed were associated with unfavorable cardiometabolic health markers, such as higher body mass index (bedtime regularity: 0.194, 95% CI [0.072, 0.316], p = 0.002); higher diastolic blood pressure levels (time in bed regularity: 0.175, 95% CI [0.044, 0.306], p = 0.009); and higher 2-h glucose levels (wake-up time regularity: 0.107, 95% CI [0.030, 0.184], p = 0.006). When we considered total physical activity with other covariates, only irregular bedtime was associated with higher waist circumference (B 0.199, 95% CI [0.042, 0.356], p = 0.013). Irregularities in bedtime and wake-up time were not associated with higher diastolic blood pressure, higher visceral fat area or higher fasting insulin level after considering sedentary time or total physical activity with other covariates (in all, p > 0.05).ConclusionsIn middle-aged, physical activity appears to weaken the adverse relationship between irregular sleep and cardiometabolic health markers, although the interpretation of the impact of sedentary time remains less conclusive. The clinical significance and extent of the observed associations warrant further investigation.

Does sleep link child maltreatment to depressive symptoms among incoming first-year college students?

We examined whether sleep (i.e. quality, regularity, and duration) mediated associations between child maltreatment (CM) and depressive symptoms among emerging adults undergoing the major life transition of starting college. Students (N = 1400; 44% male; 48% non-Hispanic white, 20% non-Hispanic Asian, 15% Hispanic all races, 7% non-Hispanic black, and 10% non-Hispanic other races) completed daily sleep diaries for 9 weeks, followed by the Childhood Trauma Questionnaire-Short Form, Pittsburgh Sleep Quality Index, and the Center for Epidemiologic Studies Depression Scale (CES-D). DSD data were used to compute participants' Sleep Regularity Index and average 24-hour total sleep time. We used a nonparametric structural equation modeling bootstrap approach and full information maximum likelihood to account for missing data. In model 1, we controlled for sex and race and ethnicity. In model 2, we further adjusted for baseline CES-D scores. The prevalence of self-reported moderate-to-severe CM was 22%. Small but significant indirect effects of CM on greater depressive symptoms through worse sleep quality (β = 0.06, 95% CI = 0.04, 0.09) and lower sleep regularity (β = 0.02, 95% CI = 0.005, 0.03) were observed in model 1. In model 2, only the indirect effect of sleep quality remained significant (β = 0.03, 95% CI = 0.01, 0.06). Poorer sleep quality may partially account for associations between CM and depressive symptoms during the first semester of college. Including sleep as a target in student health interventions on college campuses may not only help buffer against poor mental health outcomes for students with CM, but also poor academic and socioeconomic outcomes long-term.

Observational study to understand the effect of timing and regularity on sleep metrics and cardiorespiratory parameters using data from a smart bed

ABSTRACT Sleep regularity and chronotype can affect health, performance, and overall well-being. This observational study examines how sleep regularity and chronotype affect sleep quality and cardiorespiratory metrics. Data was collected from 1 January 2019 through 30 December 2019 from over 330 000 Sleep Number smart bed users across the United States who opted into this at-home study. A pressure signal from the smart bed reflected bed presence, movements, heart rate (HR), and breathing rate (BR). Participants (mean age: 55.69 years [SD: 14.0]; 51.2% female) were categorized by chronotype (16.8% early; 62.2% intermediate, 20.9% late) and regularity of sleep timing. Participants who were regular sleepers (66.1%) experienced higher percent restful sleep and lower mean HR and BR compared to the 4.8% categorized as irregular sleepers. Regular early-chronotype participants displayed better sleep and cardiorespiratory parameters compared to those with regular late-chronotypes. Significant variations were noted in sleep duration (Cohen’s d = 1.54 and 0.88, respectively) and restful sleep (Cohen’s d = 1.46 and 0.82, respectively) between early and late chronotypes, particularly within regular and irregular sleep patterns. This study highlights how sleep regularity and chronotype influence sleep quality and cardiorespiratory metrics. Irrespective of chronotype, sleep regularity demonstrated a substantial effect. Further research is necessary to confirm these findings.

Light exposure during sleep is bidirectionally associated with irregular sleep timing: The multi-ethnic study of atherosclerosis (MESA)

Exposure to light at night (LAN) may influence sleep timing and regularity. Here, we test whether greater light exposure during sleep (LEDS) is bidirectionally associated with greater irregularity in sleep onset timing in a large cohort of older adults in cross-sectional and short-term longitudinal (days) analyses. Light exposure and activity patterns, measured via wrist-worn actigraphy (ActiWatch Spectrum), were analyzed in 1933 participants with 6+ valid days of data in the Multi-Ethnic Study of Atherosclerosis (MESA) Exam 5 Sleep Study. Summary measures of LEDS averaged across nights were evaluated in linear and logistic regression analyses to test the association with standard deviation (SD) in sleep onset timing (continuous variable) and irregular sleep onset timing (SD > 90 min, binary). Night-to-night associations between LEDS and absolute differences in nightly sleep onset timing were also evaluated with distributed lag non-linear models and mixed models. In between-individual linear and logistic models adjusted for demographic, health, and seasonal factors, every 5-lux unit increase in LEDS was associated with a 7.8-min increase in sleep onset SD (β = 0.13 h, 95%CI:0.09–0.17) and 32% greater odds (OR = 1.32, 95%CI:1.17–1.50) of irregular sleep onset. In within-individual night-to-night mixed model analyses, every 5-lux unit increase in LEDS the night prior was associated with a 2.2-min greater deviation of sleep onset the next night (β = 0.036 h, p < 0.05). Conversely, every 1-h increase in sleep deviation was associated with a 0.35-lux increase in future LEDS (β = 0.348 lux, p < 0.05). LEDS was associated with greater irregularity in sleep onset in between-individual analyses and subsequent deviation in sleep timing in within-individual analyses, supporting a role for LEDS in irregular sleep onset timing. Greater deviation in sleep onset was also associated with greater future LEDS, suggesting a bidirectional relationship. Maintaining a dark sleeping environment and preventing LEDS may promote sleep regularity and following a regular sleep schedule may limit LEDS.

Validation of the Chinese version of the Sleep Regularity Questionnaire (SRQ) and analysis of influencing factors

BackgroundCurrently, there is no instrument to measure sleep regularity in China. In this study, the Sleep Regularity Questionnaire（SRQ） was translated into Chinese, tested for reliability and validity, and analyzed for factors affecting sleep regularity. MethodsThe English version of the SRQ was translated into Chinese, and a total of 3642 individuals were included in this research. Exploratory factor analysis (EFA) and confirmatory factor analysis (CFA) were used to examine the underlying factor structure of the Chinese version of the SRQ and to measure its reliability and validity. In addition, the correlations between sleep regularity and general information, personal habits, self-control, stress, anxiety, and depression were explored. ResultsThe Cronbach's α of the Chinese SRQ was 0.858, supporting the two-factor structure. Sleep regularity was statistically different between gender and ethnicity (p < 0.05), and personal habits (exercise, continued eating after dinner, smoking and drinking) had an effect on sleep regularity. Sleep regularity was positively associated with individual self-control and negatively associated with stress, anxiety, and depression. ConclusionsThe Chinese version of the SRQ has excellent reliability and validity. There are two dimensions, namely circadian regularity and sleep continuity regularity, which can be used to assess the sleep regularity of Chinese adults. The results of this study showed that males and Han Chinese having better sleep regularity. And people with good lifestyle habits and greater self-control sleep more regularly, while stress, anxiety and depression can affect individuals' sleep regularity.

Psychosocial determinants of healthy sleep habits in adults with type 1 and type 2 diabetes

ABSTRACT Background: Many adults with type 1 (T1D) and type 2 diabetes (T2D) have inadequate sleep increasing their risk of hyperglycemia and developing complications. The objective was to identify psychosocial determinants of healthy sleep habits (HSH) among adults with T1D and T2D. Methods: The two HSH were: avoiding screen use in bed and having sleep regularity. Adults (≥18 years) with T1D and T2D were invited to complete an anonymous online survey. The questionnaires were based on the Reasoned Action Approach and formative qualitative research previously conducted in 56 adults with T1D and T2D. Habit was included as an additional variable for screen use in bed. Results: In total, 320 adults with diabetes (T1D: 39%; T2D: 61%) completed the questionnaires (screen use in bed: 174; sleep timing: 146). Close to 75% of participants reported screen use in bed and close to 90% reported sleep timing variability in the last month. Perceived behavioral control (PBC) to avoid screen use in bed (β = −0.4486, p < 0.0001), habit of using screens in bed (β = 0.4002; p < 0.0001), and age (β = −0.0202; p = 0.0086) were determinants of screen use in bed, and this model explained 71% of the variance. PBC for sleep regularity (β = −0.2909; p = 0.0004) and being female (β = 0.5057; p = 0.0069) were determinants of sleep timing variability, and this model explained 28% of the variance. The most important beliefs associated with each HSH were identified to obtain information to design targeted interventions. Conclusions: Few adults with diabetes have HSH. Screen use in bed was strongly influenced by habit and the results suggest that both HSH are not easy to adopt among adults with diabetes. Younger adults with diabetes should be prioritized for screen use in bed, while females with diabetes should be prioritized for sleep timing variability. Adults with diabetes should have access to behavior change interventions to encourage them to adopt HSH.

HEALTH AND FUNCTION FROM MID LIFE TO LATE ADULTHOOD: FINDINGS FROM THE STUDY OF WOMEN’S HEALTH ACROSS THE NATION (SWAN)

Abstract Midlife (age 40-64) is characterized by physiologic, psychosocial and situational change, and a time when women experience the seminal endocrinological event of menopause. From a lifecourse perspective, understanding the relationship between midlife and older adult health is critical, particularly for identifying modifiable factors in midlife that impact later life health and functioning. Previous research has demonstrated that midlife health and functioning is dynamic and thus potentially amenable to intervention, though there remain crucial gaps in our understanding of this period. The Study of Women’s Health Across the Nation (SWAN) is an observational multi-racial/ethnic (White, Black, Chinese, Japanese, Hispanic) longitudinal study of 3,302 women recruited in 1996 from 7 sites in the United States (Boston, MA; Newark, NJ; Pittsburgh, PA; Detroit-area, MI; Chicago, IL; Oakland, CA; Los Angeles, CA). Over the past 27 years, women have participated in up to 17 near-annual study visits, spanning from midlife (age 42-52 years at baseline) to later life (age 69-79 years). This symposium features new science from SWAN including: an examination of rate of change in depressive symptoms across the menopausal transition (Avis); the impact of impaired glucose levels in midlife on muscle quality and power (Leis); the importance of sleep regularity for cognitive function (Derby); and the association of urinary incontinence with disability (Dugan). The symposium provides information regarding data and biospecimen access for investigators interested in using SWAN resources (Brooks). The Discussant will consider the implications of studying midlife health and function in relation to health and well-being in late adulthood.

Associations Between Physical Activity and Inactivity Levels on Physical Function and Sleep Parameters of Older Adults With Frailty Phenotype.

This study investigated the relationship between physical activity, inactivity, physical function, and sleep in older adults with a frailty phenotype. A total of 184 pre-frail/frail older adults were included. Physical activity, inactive behavior, and sleep parameters were assessed using a wrist-worn accelerometer. Participants were categorized into four groups based on their levels of inactivity and physical activity. The results showed that individuals with lower levels of inactivity had better lower body mean velocity and sleep regularity than those with higher levels of inactivity. Physically active older adults exhibited faster gait speed and performed better in lower body strength tests than physically inactive participants. Further analysis revealed that specific combinations of inactivity and physical activity were associated with varying levels of physical function. The findings highlight the importance of physical activity and the negative impact of inactivity on physical function and sleep in older adults with a frailty phenotype.

Sleep regularity and mortality: a prospective analysis in the UK Biobank.

Irregular sleep-wake timing may cause circadian disruption leading to several chronic age-related diseases. We examined the relationship between sleep regularity and risk of all-cause, cardiovascular disease (CVD), and cancer mortality in 88,975 participants from the prospective UK Biobank cohort. The sleep regularity index (SRI) was calculated as the probability of an individual being in the same state (asleep or awake) at any two time points 24 hr apart, averaged over 7 days of accelerometry (range 0-100, with 100 being perfectly regular). The SRI was related to the risk of mortality in time-to-event models. The mean sample age was 62 years (standard deviation [SD], 8), 56% were women, and the median SRI was 60 (SD, 10). There were 3010 deaths during a mean follow-up of 7.1 years. Following adjustments for demographic and clinical variables, we identified a non-linear relationship between the SRI and all-cause mortality hazard (p [global test of spline term]<0.001). Hazard ratios, relative to the median SRI, were 1.53 (95% confidence interval [CI]: 1.41, 1.66) for participants with SRI at the 5th percentile (SRI = 41) and 0.90 (95% CI: 0.81, 1.00) for those with SRI at the 95th percentile (SRI = 75), respectively. Findings for CVD mortality and cancer mortality followed a similar pattern. Irregular sleep-wake patterns are associated with higher mortality risk. National Health and Medical Research Council of Australia (GTN2009264; GTN1158384), National Institute on Aging (AG062531), Alzheimer's Association (2018-AARG-591358), and the Banting Fellowship Program (#454104).

Sleep regularity and mortality: a prospective analysis in the UK Biobank

Background:Irregular sleep-wake timing may cause circadian disruption leading to several chronic age-related diseases. We examined the relationship between sleep regularity and risk of all-cause, cardiovascular disease (CVD), and cancer mortality in 88,975 participants from the prospective UK Biobank cohort.Methods:The sleep regularity index (SRI) was calculated as the probability of an individual being in the same state (asleep or awake) at any two time points 24 hr apart, averaged over 7 days of accelerometry (range 0–100, with 100 being perfectly regular). The SRI was related to the risk of mortality in time-to-event models.Results:The mean sample age was 62 years (standard deviation [SD], 8), 56% were women, and the median SRI was 60 (SD, 10). There were 3010 deaths during a mean follow-up of 7.1 years. Following adjustments for demographic and clinical variables, we identified a non-linear relationship between the SRI and all-cause mortality hazard (p [global test of spline term]&lt;0.001). Hazard ratios, relative to the median SRI, were 1.53 (95% confidence interval [CI]: 1.41, 1.66) for participants with SRI at the 5th percentile (SRI = 41) and 0.90 (95% CI: 0.81, 1.00) for those with SRI at the 95th percentile (SRI = 75), respectively. Findings for CVD mortality and cancer mortality followed a similar pattern.Conclusions:Irregular sleep-wake patterns are associated with higher mortality risk.Funding:National Health and Medical Research Council of Australia (GTN2009264; GTN1158384), National Institute on Aging (AG062531), Alzheimer’s Association (2018-AARG-591358), and the Banting Fellowship Program (#454104).

Sleep/Wake Regularity and Cognition in College Students using Antidepressants

The current project examined sleep, sleep/wake regularity, and cognition in college students diagnosed with depression and using serotonergic antidepressants and in those without a depression diagnosis. Forty participants either using antidepressants (n = 20, 24.75 ± 6.82 years) or without a depression diagnosis (n = 20, 21.70 ± 2.74 years) wore actigraphs for two consecutive weeks (14 days). Cognitive tasks were completed on day 1 (along with demographic surveys) and day 14. Effect sizes indicated that compared to non-clinically depressed peers, participants using antidepressants exhibited slightly greater wake after sleep onset (d = .36) and lower sleep efficiency (d = .40); however, these differences were likely not noticed by the sleeper. No sleep regularity or cognitive differences were present between groups. Within the antidepressant group, higher dosage predicted greater time in bed (R2 = .77), but less total sleep time (R2 = .86). The time of day that participants took their antidepressant exhibited differential effects on certain cognitive parameters, such as procedural reaction time and spatial processing, and interactions with years of antidepressant use were found. Self-reported wake episodes also predicted better reaction time and inhibition in the antidepressant group. This study is the first to demonstrate that sleep/wake regularity is comparable between people using antidepressants and non-clinically depressed human samples. For individuals using antidepressants, years of use, dosage, and time of day of use have predictive qualities for reaction times, spatial processing, and inhibition.

Evaluation of sleep strategies between night shifts in actual shift workers

ObjectivesThe aim of this observational study was to examine sleep obtained between consecutive night shifts from shift workers in their natural environment. The goal was to identify the various sleep strategies and the timing, duration, regularity, and quality of sleep associated with the strategies. MethodsParticipants (N = 33, 23 women, aged 40 ± 15years) reported their sleep information in daily diaries over 2weeks while working at least one series of consecutive night shifts. Sleep timing, duration, quality, and regularity were calculated for each sleep episode between consecutive night shifts. ResultsBased on the reported sleep behavior, shift workers were categorized as either morning, delayed, split- or mixed sleepers. We found significant differences between the groups in timing of sleep, feeling refreshed, and regularity of sleep between consecutive night shifts, whereas duration and subjective soundness of sleep did not show significant differences. ConclusionsIn this sample, four sleep strategies were observed between consecutive night shifts in actual shift workers. These observations may help design future interventions to improve sleep that are individualized to the worker.

The association between cortical gyrification and sleep in adolescents and young adults.

Healthy sleep is important for adolescent neurodevelopment, and relationships between brain structure and sleep can vary in strength over this maturational window. Although cortical gyrification is increasingly considered a useful index for understanding cognitive and emotional outcomes in adolescence, and sleep is also a strong predictor of such outcomes, we know relatively little about associations between cortical gyrification and sleep. We aimed to identify developmentally invariant (stable across age) or developmentally specific (observed only during discrete age intervals) gyrification-sleep relationships in young people. A total of 252 Neuroimaging and Pediatric Sleep Databank participants (9-26 years; 58.3% female) completed wrist actigraphy and a structural MRI scan. Local gyrification index (lGI) was estimated for 34 bilateral brain regions. Naturalistic sleep characteristics (duration, timing, continuity, and regularity) were estimated from wrist actigraphy. Regularized regression for feature selection was used to examine gyrification-sleep relationships. For most brain regions, greater lGI was associated with longer sleep duration, earlier sleep timing, lower variability in sleep regularity, and shorter time awake after sleep onset. lGI in frontoparietal network regions showed associations with sleep patterns that were stable across age. However, in default mode network regions, lGI was only associated with sleep patterns from late childhood through early-to-mid adolescence, a period of vulnerability for mental health disorders. We detected both developmentally invariant and developmentally specific ties between local gyrification and naturalistic sleep patterns. Default mode network regions may be particularly susceptible to interventions promoting more optimal sleep during childhood and adolescence.

The Social Structures of Sleep: Effects of Work-Related and Family Constraints on Sleep Duration and Regularity Among French Workers

Previous research shows that sleep time is shaped by family constraints and paid work organisation. However, the impact of both work and family on sleep routines is relatively unknown. Using the 2009–2010 French Time Use Survey, this article examines how workers’ sleep routines are affected by paid work and family situation, and emphasises the social significance of sleep patterns. Paid work and family situation both structure the duration and regularity of sleep. Paid work reduces sleep time and has a disruptive effect on sleep routines, but to different degrees depending on socio-occupational category and work schedule. Having a small child has a negative effect on sleep on any given day, but works in favour of a regular sleep routine, as well as the tendency for spouses to synchronise. However, the regulating effect of family life accentuates the disruptive effect of paid work for the most atypical work schedules.

P077 Associations of sex, sleep, and circadian rhythms with performance in elite Australian Rules footballers

Abstract Introduction Poor sleep and circadian misalignment are associated with poorer performance. In elite Australian Rules football (ARF), both sex and professionalism could alter or exacerbate these associations. This study provides preliminary insights on how the relationships of sleep and circadian alignment with cognitive performance differ between male full-professional and female semi-professional elite ARF athletes. Methods Participants were 72 elite ARF athletes (42% female; M-age = 24.1±4.4 years). During pre-season, participants completed two weeks of sleep/wake monitoring via actigraphy, and a circadian phase assessment (dim light melatonin onset; DLMO) after one week. Cognitive performance testing (psychomotor vigilance task, PVT; and the balloon analogue risk task; BART) was conducted five times throughout this period. Results Preliminary findings suggest average total sleep time and sleep efficiency, sleep regularity, DLMO, and phase angle (interval between average sleep onset and DLMO) did not predict reaction time on the PVT, nor did sex moderate these relationships. After controlling for sex, longer sleepers demonstrated greater risk taking on the BART. Only among male athletes did larger angles predict greater risk taking. Discussion Elite ARF athletes, regardless of sex, sleep, or circadian alignment, have similar reaction times. Risk taking is greater among longer sleepers and in male athletes experiencing relatively delayed circadian phases. Where risk-taking has negative implications (e.g., injury and sporting errors), these findings identify at-risk groups. Few sex-specific findings may suggest that the semi-professional status of female ARF (and associated lifestyle factors such as scheduling and income) is not altering elite performance in controlled settings.

THU303 The Associations Between Rest-Activity Parameters, Sleep-Disordered Breathing Severity And Glucose Metabolism In Patients With Prediabetes

Abstract Disclosure: J. Paewponsong: None. B.S. Gerber: None. N. Chirakalwasan: None. S. Saetung: None. T. Anothaisintawee: None. S. Reutrakul: None. Background: Circadian rhythm abnormalities and sleep-disordered breathing (SDB) can have an adverse effect on glucose metabolism. In addition, studies have suggested that SDB itself could be associated with circadian disruption. This study aimed to determine if circadian characteristics, as measured by rest-activity rhythm parameters, were connected with SDB severity in individuals with prediabetes, and whether rest-activity rhythm parameters were related with glycemia. Methods: A total of 79 patients with prediabetes were enrolled. Actigraphy recordings (Actiwatch 2, Phillips Respironics) spanning 7 days yielded non-parametric rest-activity rhythm parameters and sleep duration. The parameters included M10 (mean activity of the most active 10-h period), L5 (mean activity of the least active 5-h period), intradaily variability (reflecting rhythm fragmentation), interdaily stability (reflecting sleep regularity across days), and relative amplitude (reflecting the activity between M10 and L5 activity). SDB was assessed using an overnight sleep monitor (WatchPAT200). Fasting blood glucose (FBG) and hemoglobin A1c (HbA1c) were obtained via phlebotomy. Independent predictors of rest-activity rhythm parameters, FBG, and HbA1c were determined using multiple stepwise regression analyses. Model covariates included age, sex, body mass index (BMI), and SDB severity. Results: Increasing SDB severity was associated with lower M10 and greater intradaily variability, but not with FBG, HbA1c or other rest-activity rhythm parameters. After adjusting for age, sex and BMI, increasing SDB severity was independently related with lower M10 (B= -0.102, p=0.001). Further, bivariate analyses showed that a higher HbA1c was associated with a shorter sleep duration, lower relative amplitude, and higher L5. FBG was not related to any rest-activity rhythm parameters. After adjusting for age, sex, BMI and sleep duration, lower relative amplitude, but not L5, was independently related with higher HbA1c (B= −0.027, p=0.031). Conclusion: In prediabetes, a lower relative amplitude, indicating a less robust 24 hour rest-activity rhythm, was associated with a higher HbA1c. These findings suggest that circadian rhythmicity contributes to glycemic control. Greater SDB severity was correlated with decreased activity, but relationships with other rest-activity rhythm parameters were not observed. Presentation: Thursday, June 15, 2023

Late evening electric light exposure is associated with low sleep regularity in adolescents living in rural areas

In this study, we tested the prediction that sleep regularity would be lower in adolescents exposed to late evening electric light (LEEL) than in those without exposure to it. The Sleep Regularity Index was calculated based on actigraph recordings from adolescents living in rural communities in Argentina and Brazil that were either exposed to LEEL or not. The effect of the LEEL on sleep variables was tested using linear models considering sex and age, as well as accounting for the differences between countries. Sleep onset was delayed, sleep duration shortened, and Sleep Regularity Index was 4 [1-8] points lower in the group exposed to LEEL (p = .0176, eta2 =0.13). Our results show that beyond sleep phase and duration, which are known to be affected by LEEL in this age group, sleep irregularity should also be considered as an important outcome variable when assessing the adverse effects of evening light on adolescents.