A Protocol to Determine Circadian Phase by At-Home Salivary Dim Light Melatonin Onset Assessment.

Internal circadian phase assessment is increasingly acknowledged as a critical clinical tool for the diagnosis, monitoring, and treatment of circadian rhythm sleep-wake disorders and for investigating circadian timing in other medical disorders. The widespread use of in-laboratory circadian phase assessments in routine practice has been limited, most likely because circadian phase assessment is not required by formal diagnostic nosologies, and is not generally covered by insurance. At-home assessment of salivary dim light melatonin onset (DLMO, a validated circadian phase marker) is an increasingly accepted approach to assess circadian phase. This approach may help meet the increased demand for assessments and has the advantages of lower cost and greater patient convenience. We reviewed the literature describing at-home salivary DLMO assessment methods and identified factors deemed to be important to successful implementation. Here, we provide specific protocol recommendations for conducting at-home salivary DLMO assessments to facilitate a standardized approach for clinical and research purposes. Key factors include control of lighting, sampling rate, and timing, and measures of patient compliance. We include findings from implementation of an optimization algorithm to determine the most efficient number and timing of samples in patients with Delayed Sleep-Wake Phase Disorder. We also provide recommendations for assay methods and interpretation. Providing definitive criteria for each factor, along with detailed instructions for protocol implementation, will enable more widespread adoption of at-home circadian phase assessments as a standardized clinical diagnostic, monitoring, and treatment tool.

Bipolar disorder is characterized by chronotype instability: A longitudinal investigation of circadian typology and mood.

BACKGROUND: Chronotype is associated with circadian rhythmicity, a core etiological factor underlying bipolar disorder (BD). Given converging evidence linking late chronotype with poor mental health, the goal of the present study was to examine chronotype (in)stability and its relation to mood symptoms over time. METHODS: Participants with BD I (n = 271), BD II (n = 88), and healthy controls (n = 217) were included (follow-upM=10 years, Range=5-15) from the Prechter Longitudinal Study. Chronotype category and midpoint of sleep, corrected for weekend sleep-debt (MSFsc), were measured with the Munich Chronotype Questionnaire administered every 12 months alongside clinician-rated mood and medication usage. Self-reported mood was measured bi-monthly. Mixed effects models tested whether mood was associated with (in)stability of chronotype category and MSFsc covarying for age, sex, age, and medication. RESULTS: Compared to HC, individuals with BD self-reported having a later chronotype that significantly fluctuated over time. Individuals with BDI showed significantly less stability in MSFsc than HC. Anticonvulsant use was associated with more stability in MSFsc whereas antidepressant use was associated with less stability in MSFsc. CONCLUSIONS: In a large longitudinal cohort, individuals with BD displayed significant instability in circadian typology. Psychopharmacology in BD may have differential impacts on circadian timing that is important to monitor.

Morning light treatment for inflammatory bowel disease: a clinical trial.

BACKGROUND: Inflammatory bowel disease (IBD) affects over 3 million Americans and has a relapsing and remitting course with up to 30% of patients experiencing exacerbations each year despite the availability of immune targeted therapies. An urgent need exists to develop adjunctive treatment approaches to better manage IBD symptoms and disease activity. Circadian disruption is associated with increased disease activity and may be an important modifiable treatment target for IBD. Morning light treatment, which advances and stabilizes circadian timing, may have the potential to improve IBD symptoms and disease activity, but no studies have explored these potential therapeutic benefits in IBD. Therefore, in this study, we aim to test the effectiveness of morning light treatment for patients with IBD. METHODS: We will recruit sixty-eight individuals with biopsy-proven IBD and clinical symptoms and randomize them to 4-weeks of morning light treatment or 4-weeks of treatment as usual (TAU), with equivalent study contact. Patient-reported outcomes (IBD-related quality of life, mood, sleep), clinician-rated disease severity, and a biomarker of gastrointestinal inflammation (fecal calprotectin) will be assessed before and after treatment. Our primary objective will be to test the effect of morning light treatment versus TAU on IBD-related quality of life and our secondary objectives will be to test the effects on clinician-rated disease activity, depression, and sleep quality. We will also explore the effect of morning light treatment versus TAU on a biomarker of gastrointestinal inflammation (fecal calprotectin), and the potential moderating effects of steroid use, restless leg syndrome, and biological sex. DISCUSSION: Morning light treatment may be an acceptable, feasible, and effective adjunctive treatment for individuals with active IBD suffering from impaired health-related quality of life. TRIAL REGISTRATION: The study protocol was registered on ClinicalTrials.gov as NCT06094608 on October 23, 2023, before recruitment began on February 1, 2024.

Do sleep and circadian characteristics predict alcohol use in adult drinkers?

BACKGROUND: While sleep and circadian rhythms are recognized contributors to the risk for alcohol use and related problems, few studies have examined whether objective sleep and circadian measures can predict future alcohol use in humans, and no such studies have been conducted in adults. This study examined whether any baseline sleep and/or circadian characteristics of otherwise healthy adults predicted their alcohol use over the subsequent 12 months. METHODS: Participants (21-42 years) included 28 light and 50 heavy drinkers. At baseline, a comprehensive range of self-reported and objective sleep/circadian measures was assessed via questionnaires, wrist actigraphy, and measurement of dim light melatonin onset and circadian photoreceptor responsivity. Following this, the number of alcoholic drinks per week and binge drinking episodes per month were assessed quarterly over the subsequent 12 months. Anticipated effects of alcohol (stimulation, sedation, and rewarding aspects) were also assessed quarterly over the 12 months. Analyses included generalized linear mixed-effects models and causal mediation analysis. RESULTS: Across the range of measures, only self-reported insomnia symptoms and a longer total sleep time at baseline predicted more drinks per week and binges per month (ps <0.02). There was a trend for the anticipated alcohol effect of wanting more alcohol at the 6-month timepoint to mediate the relationship between insomnia symptoms at baseline and drinks per week at 12 months (p = 0.069). CONCLUSIONS: These results suggest that in otherwise healthy adults, insomnia symptoms, even if subclinical, are a significant predictor of future drinking, and appear to outweigh the influence of circadian factors on future drinking, at least in otherwise healthy adults. Insomnia symptoms may be a modifiable target for reducing the risk of alcohol misuse.

Sleep Disorders, Sleep Medication Use, and Predictors of Sleep Disturbance in Children with Persistent Tic Disorders.

The present study examined rates of sleep disorders and sleep medication use, and predictors of sleep disturbance in children with persistent tic disorders (PTD). Sixty-three parents of children aged 10 to 17 years with PTDs completed an internet survey evaluating sleep patterns and clinical symptoms. Insomnia (19.4%), nightmares (16.1%), and bruxism (13.1%) were the most commonly reported lifetime sleep disorders. Fifty-two percent endorsed current sleep medication use. Higher ADHD severity, overall life impairment, and female sex predicted greater sleep disturbance. Findings suggest the utility of clinical management of co-occurring ADHD and impairment to mitigate sleep disturbance in children with PTDs.

Low-dose exogenous melatonin plus evening dim light and time in bed scheduling advances circadian phase irrespective of measured or estimated dim light melatonin onset time: preliminary findings.

STUDY OBJECTIVES: The purpose of the present study was to preliminarily evaluate whether knowing the dim light melatonin onset (DLMO) time is advantageous when treating delayed sleep-wake phase disorder with low-dose melatonin treatment plus behavioral interventions (ie, evening dim light and time in bed scheduling). METHODS: In this randomized, controlled, double-blind trial, 40 adults with delayed sleep-wake phase disorder were randomly assigned to 4 weeks of 0.5 mg timed to be administered either 3 hours before the DLMO (measured DLMO group, n = 20) or 5 hours before sleep-onset time per actigraphy (estimated DLMO group, n = 20), in conjunction with behavioral interventions. The primary outcome was change in the DLMO (measured in-home). Secondary outcomes included sleep parameters per diary and actigraphy (sleep-onset and -offset times and total sleep time), Morningness-Eveningness Questionnaire, Multidimensional Fatigue Inventory, PROMIS-Sleep Disturbance, PROMIS-Sleep Related Impairment, and Pittsburgh Sleep Quality Index. Mixed-effects models tested for group differences in these outcome. RESULTS: After applying the Bonferroni correction for multiple comparisons (significant P value set at < .004), there were significant main effects for visit on all outcomes except for the Pittsburgh Sleep Quality Index and total sleep time per wrist actigraphy and diary. There were no group-by-visit interactions for any of the outcomes (P > .004). CONCLUSIONS: Scheduled low-dose melatonin plus behavioral interventions may improve many circadian and sleep parameters regardless of whether melatonin administration is scheduled based on estimated or measured DLMO. A larger-scale trial is needed to confirm these preliminary findings. CLINICAL TRIAL REGISTRATION: Registry: ClinicalTrials.gov; Name: The Clinical Utility of Measuring the Circadian Clock in Treatment of Delayed Sleep-Wake Phase Disorder; URL: https://clinicaltrials.gov/study/NCT03715465; Identifier: NCT03715465. CITATION: Swanson LM, de Sibour T, DuBuc K, et al. Low-dose exogenous melatonin plus evening dim light and time in bed scheduling advances circadian phase irrespective of measured or estimated dim light melatonin onset time: preliminary findings. J Clin Sleep Med. 2024;20(7):1131-1140.

Tryptophan-kynurenine metabolic pathway and daytime dysfunction in women with HIV.

Sleep disturbances are prevalent in women with HIV (WWH). Tryptophan-kynurenine (T-K) pathway metabolites are associated with alterations in actigraphy derived sleep measures in WWH, although may not always correlate with functional impairment. We investigated the relationship between T-K pathway metabolites and self-reported daytime dysfunction in WWH and women without HIV (WWoH). 141 WWH on stable antiretroviral therapy and 140 demographically similar WWoH enrolled in the IDOze Study had targeted plasma T-K metabolites measured using liquid chromatography-tandem mass spectrometry. We utilized the daytime dysfunction component of the Pittsburgh Sleep Quality Index (PSQI) to assess functional impairment across HIV-serostatus. Lower levels of 5-hydroxytryptophan and serotonin were associated with greater daytime dysfunction in all women. In WWH, daytime dysfunction was associated with increased kynurenic acid (R = 0.26, p < 0.05), and kynurenic acid-tryptophan (KA-T) ratio (R = 0.28, p < 0.01). WWH with daytime dysfunction had a 0.7 log fold increase in kynurenic acid compared to WWH without daytime dysfunction. Kynurenic acid levels and the KA-T ratio were associated with daytime dysfunction in WWH but not in WWoH. Longitudinal studies are needed to establish a causal relationship and directionality between T-K metabolic changes and sleep impairment in WWH.

Loneliness and Depressive Symptoms Are High Among Older Adults With Digestive Disease and Associated With Lower Perceived Health.

BACKGROUND & AIMS: Current approaches to managing digestive disease in older adults fail to consider the psychosocial factors contributing to a person's health. We aimed to compare the frequency of loneliness, depression, and social isolation in older adults with and without a digestive disease and to quantify their association with poor health. METHODS: We conducted an analysis of Health and Retirement Study data from 2008 to 2016, a nationally representative panel study of participants 50 years and older and their spouses. Bivariate analyses examined differences in loneliness, depression, and social isolation among patients with and without a digestive disease. We also examined the relationship between these factors and health. RESULTS: We identified 3979 (56.0%) respondents with and 3131 (44.0%) without a digestive disease. Overall, 60.4% and 55.6% of respondents with and without a digestive disease reported loneliness (P < .001), 12.7% and 7.5% reported severe depression (P < .001), and 8.9% and 8.7% reported social isolation (P = NS), respectively. After adjusting for covariates, those with a digestive disease were more likely to report poor or fair health than those without a digestive disease (odds ratio [OR], 1.25; 95% CI, 1.11-1.41). Among patients with a digestive disease, loneliness (OR, 1.43; 95% CI, 1.22-1.69) and moderate and severe depression (OR, 2.93; 95% CI, 2.48-3.47; and OR, 8.96; 95% CI, 6.91-11.63, respectively) were associated with greater odds of poor or fair health. CONCLUSIONS: Older adults with a digestive disease were more likely than those without a digestive disease to endorse loneliness and moderate to severe depression and these conditions are associated with poor or fair health. Gastroenterologists should feel empowered to screen patients for depression and loneliness symptoms and establish care pathways for mental health treatment.

An independent comparison of the Novolytix salivary melatonin radioimmunoassay with the new Novolytix salivary melatonin enzyme-linked immunosorbent assay.

The dim light melatonin onset (DLMO) is the current gold standard biomarker of the timing of the central circadian clock in humans and is often assessed from saliva samples. To date, only one commercially available salivary melatonin assay is considered accurate at the low daytime levels required to accurately detect the DLMO (Novolytix RIA RK-DSM2). The aim of this study was to conduct the first independent evaluation of a newly improved enzyme-linked immunosorbent assay (ELISA; Novolytix MLTN-96) and compare it with the recommended radioimmunoassay (RIA)-both in terms of melatonin concentrations and derived DLMOs. Twenty participants (15 females, 18-59 years old) provided saliva samples every 30 min in dim light starting 6 h before their habitual bedtime, yielding a total of 260 saliva samples. Both the RIA and ELISA yielded daytime melatonin concentrations <2 pg/mL, indicating adequate accuracy to detect the DLMO. The melatonin concentrations from the two assays were highly correlated (r = .94, p < .001), although the RIA yielded lower levels of melatonin concentration than the ELISA, on average by 0.70 pg/mL (p = .006). Seventeen DLMOs were calculated from the melatonin profiles and the DLMOs from both assays were not statistically different (p = .36) and were highly correlated (r = .97, p < .001). Two DLMOs derived from the RIA occurred more than 30 min earlier than the DLMO derived from the ELISA. These results indicate that the new Novolytix ELISA is an appropriate assay to use if the Novolytix RIA is not feasible or available.

Circadian timing, melatonin and hippocampal volume in later-life adults.

Hippocampal atrophy is a prominent neurodegenerative feature of Alzheimer's disease and related dementias. Alterations in circadian rhythms can exacerbate cognitive aging and neurodegeneration. This study aimed to examine how dim light melatonin onset and melatonin levels are associated with hippocampal volume in cognitively healthy individuals. We studied data from 52 later-life adults (mean age ± SD = 70.0 ± 6.3 years). T1-weighted anatomical images from 3.0 T magnetic resonance imaging data were collected and processed using the BRAINSTools toolbox. Dim light melatonin onset was used to assess circadian timing. The area under the curve was calculated to quantify melatonin concentration levels 6 hr before bedtime, and 14-day wrist actigraphy data were used to assess habitual bedtime. Multiple linear regression modelling with hippocampal volume as the dependent variable was used to analyse the data adjusting for age and sex. The average dim light melatonin onset was 19:45 hours (SD = 84 min), and area under the curve of melatonin levels 6 hr before habitual bedtime was 38.4 pg ml-1 × hr (SD = 29.3). We found that later dim light melatonin onset time (b = 0.16, p = 0.005) and greater area under the curve of melatonin levels 6 hr before habitual bedtime (b = 0.05, p = 0.046) were associated with greater adjusted hippocampal volume. The time between dim light melatonin onset and the midpoint of sleep timing was not associated with hippocampal volume. The findings suggest that earlier circadian timing (dim light melatonin onset) and reduced melatonin may be associated with reduced hippocampal volume in older adults. Future research will help researchers utilize circadian rhythm information to delay brain aging.

Early-to-mid pregnancy sleep and circadian markers in relation to birth outcomes: An epigenetics pilot study.

Maternal sleep and circadian health during pregnancy are emerging as important predictors of pregnancy outcomes, but examination of potential epigenetic mechanisms is rare. We investigated links between maternal leukocyte DNA methylation of circadian genes and birth outcomes within a pregnancy cohort. Women (n = 96) completed a questionnaire and provided a blood sample at least once during early-to-mid pregnancy (average gestation weeks = 14.2). Leukocyte DNA was isolated and DNA methylation (average percent of methylation) at multiple CpG sites within BMAL1, PER1, and MTNR1B genes were quantified by pyrosequencing. Birth outcomes including gestational age at delivery, birthweight, and head circumference were abstracted from medical charts. Linear regression analyses were run between each CpG site with birth outcomes, adjusting for important confounders. Sleep duration and timing were assessed as secondary exposures. Higher methylation of a CpG site in PER1 was associated with smaller log-transformed head circumference (ß=-0.02 with 95% CI -0.02 to 0.01; P, trend = 0.04). Higher methylation of MTNR1B (averaged across sites) was associated with lower log-transformed birthweight (-0.08 with 95% CI -0.16 to -0.01; P, trend = 0.0495). In addition, longer sleep duration was associated with higher birthweight (0.10 with 95% CI 0.02 to 0.18 comparing > 9 h to < 8 h; P, trend = 0.04). This pilot investigation revealed that higher methylation of PER1 and MTNR1B genes, and sleep duration measured in early-to-mid pregnancy were related to birth outcomes.

Association of Gut Microbiota With Objective Sleep Measures in Women With and Without Human Immunodeficiency Virus Infection: The IDOze Study.

BACKGROUND: Poor sleep health is an underrecognized health challenge, especially for people with human immunodeficiency virus (HIV). Gut microbiota related to sleep are underinvestigated. METHODS: The IDOze microbiota substudy included 190 women (114 with HIV and 76 without HIV). Wrist actigraphy measured total sleep duration, sleep efficiency, number of wake bouts, wake after sleep onset, fragmentation index, and sleep timing. 16S rRNA gene sequencing identified gut microbial genera. Analysis of compositions of microbiomes with bias correction was used to investigate cross-sectional associations between gut microbiota and sleep. Abundances of sleep-related gut microbial genera were compared between women with and without HIV. RESULTS: Enrichment of 7 short-chain fatty acid-producing genera (eg, Butyricimonas, Roseburia, and Blautia) was associated with lower fragmentation index. Enrichment of 9 genera (eg, Dorea) was associated with lower sleep efficiency and/or more wake after sleep onset. Enrichment of proinflammatory Acidaminococcus was associated with late sleep midpoint and offset time. These associations were largely consistent regardless of HIV status. The abundance of Butyricimonas was lower among women with HIV compared to those without HIV. CONCLUSIONS: Seventeen genera were identified to be associated with sleep continuity or timing. Butyricimonas, a potentially beneficial genus associated with sleep continuity, was less abundant among women with HIV.

Overnight urinary melatonin levels in women with and without HIV: An observational cohort study.

INTRODUCTION: Despite significant improvements in longevity and quality of life associated with antiretroviral therapy, individuals with HIV still suffer from a higher burden of sleep and circadian disruption and inflammatory-based diseases than individuals without HIV. While melatonin is a hormone that has a role in sleep and circadian regulation and has anti-inflammatory properties, the overnight concentration of the urinary melatonin metabolite has not yet been reported in people with HIV. METHODS: The aim of this study was to compare the overnight urinary melatonin metabolite levels in women aged 35-70 years with HIV (n = 151) to a well-matched comparison group of women without HIV (n = 147). All women wore a wrist actigraphy monitor and completed daily diaries documenting sleep timing and use of medications and drugs or alcohol for 10 days. Participants collected their overnight urine near the end of the monitoring period. RESULTS: Melatonin levels did not differ between women with or without HIV, but more than 40% of women had low levels of melatonin. Higher body mass index predicted lower levels of melatonin, and lower levels of melatonin were associated with lower sleep efficiency as assessed with wrist actigraphy. CONCLUSION: These data lay the foundation for exploration of the longitudinal consequences of endogenous melatonin levels for inflammatory-based diseases in aging women with and without HIV. Future studies should consider the use of supplemental melatonin to improve sleep in women with lower levels of melatonin.

What a difference a year makes: Objective rest/activity patterns, circadian phase markers, and sleep quality before and during the COVID-19 pandemic.

OBJECTIVES: The COVID-19 pandemic led to numerous changes in sleep duration, quality, and timing. The goal of this study was to examine objective and self-reported changes in sleep and circadian timing before and during the pandemic. METHODS: Data were utilized from an ongoing longitudinal study of sleep and circadian timing with assessments at baseline and 1-year follow-up. Participants had baseline assessment between 2019 and March 2020 (before pandemic) and 12-month follow-up between September 2020 and March 2021 (during pandemic). Participants completed 7 days of wrist actigraphy, self-report questionnaires, and laboratory-collected circadian phase assessment (dim light melatonin onset). RESULTS: Actigraphy and questionnaire data were available for 18 participants (11 women and 7 men, Mean = 38.8 years, SD = 11.8). Dim light melatonin onset was available for 11 participants. Participants demonstrated statistically significant decreases in sleep efficiency (Mean = -4.11%, SD = 3.22, P = .001), worse scores on Patient-Reported Outcome Measurement Information System sleep disturbance scale (Mean increase = 4.48, SD = 6.87, P = .017), and sleep end time delay (Mean = 22.4 mins, SD = 44.4 mins, P = .046). Chronotype was significantly correlated with change in dim light melatonin onset (r = 0.649, P = .031). This suggests that a later chronotype is associated with a greater delay in dim light melatonin onset. There were also non-significant increases in total sleep time (Mean = 12.4 mins, SD = 44.4 mins, P = .255), later dim light melatonin onset (Mean = 25.2 mins, SD = 1.15 hrs, P = .295), and earlier sleep start time (Mean = 11.4 mins, SD = 48 mins, P = .322). CONCLUSION: Our data demonstrate objective and self-reported changes to sleep during the COVID-19 pandemic. Future studies should look at whether some individuals will require intervention to phase advance sleep when returning to previous routines such as returning to office and school settings.

Sleep duration and timing are prospectively linked with insulin resistance during late adolescence.

OBJECTIVE: The aim of this study was to evaluate whether short sleep duration or later sleep timing is a risk factor for insulin resistance (IR) in late adolescence. METHODS: Mexico City adolescents enrolled in a longitudinal birth cohort (ELEMENT) took part in two study visits during peri-puberty that occurred approximately 2 years apart. IR was assessed with serum glucose and insulin. Four groups were defined using puberty-specific cut points: no IR over the follow-up period, transition from normal to IR, transition from IR to normal, and IR at both time points. Baseline sleep assessments were measured with 7-day wrist actigraphy. Multinomial logistic regression models were used to evaluate associations between sleep duration and timing with homeostatic model assessment of insulin resistance categories, adjusting for age, sex, and baseline pubertal status. RESULTS: Adolescents who were ≥ 1 hour below the sleep duration recommendations-for-age were 2.74 times more likely to develop IR (95% CI: 1.0-7.4). Similarly, adolescents who were in the latest category of sleep midpoint (>4:33 a.m.) were more likely than those with earliest midpoints (1 a.m.-3 a.m.) to develop IR (odds ratio = 2.63, 95% CI: 1.0-6.7). Changes in adiposity over follow-up did not mediate sleep and IR. CONCLUSIONS: Insufficient sleep duration and late sleep timing were associated with development of IR over a 2-year period in late adolescence.

Objective and Subjective Sleep Measures Are Related to Suicidal Ideation and Are Transdiagnostic Features of Major Depressive Disorder and Social Anxiety Disorder.

Suicide is a major public health problem and previous studies in major depression and anxiety show problematic sleep is a risk factor for suicidal ideation (SI). However, less is known about sleep and SI in social anxiety disorder (SAD), despite the pervasiveness of SAD. Therefore, the current study comprised participants with major depressive disorder (MDD) (without comorbid SAD) (n = 26) and participants with SAD (without comorbid MDD) (n = 41). Wrist actigraphy was used to estimate sleep duration, wake after sleep onset, and sleep efficiency; sleep quality was evaluated with self-report. Self-report was also used to examine SI. These measures were submitted to independent t-tests and multiple regression analysis. t-test results revealed sleep and SI did not differ between MDD and SAD groups. Multiple regression results showed shorter sleep duration and worse sleep quality related to greater SI when taking symptom severity and age into account. Post-hoc partial correlational analysis showed these sleep-SI relationships remained significant after controlling for symptom severity and age. Preliminary findings indicate sleep and SI may be transdiagnostic features of MDD and SAD. Evidence of distinct sleep-SI relationships are consistent with previous reports showing that sleep difficulties contribute to SI. Altogether, improving sleep duration and sleep quality may reduce the risk of SI.

Circadian Timing, Information processing and Metabolism (TIME) study: protocol of a longitudinal study of sleep duration, circadian alignment and cardiometabolic health among overweight adults.

BACKGROUND: Both short sleep duration and circadian rhythm misalignment are risk factors for metabolic dysfunction, but the underlying mechanisms are unknown. The goal of this study is to examine how sleep duration and circadian alignment predict changes in cardiometabolic risk factors over a 12-month period, and test cognitive function and hedonic eating tendencies as potential mechanisms. METHODS: We will recruit a sample of 120 working aged adults with BMI 25-35 kg/m2 (overweight to class I obesity). The protocol includes 5 visits over a 12-month period. Study visits include wrist actigraphy to measure sleep behaviors, 24-h diet recalls, dim light melatonin collection, a computerized neurobehavioral assessment, eating in the absence of hunger task, and frequently sampled IV glucose tolerance test. DISCUSSION: The results of the TIME study will advance the understanding of how both short sleep duration and circadian misalignment contribute to behavioral aspects of obesity and metabolic dysfunction. TRIAL REGISTRATION: ClinicalTrials.Gov, NCT04759755 , registered retrospectively February 13, 2021.