Autonomic dysfunction: a possible pathophysiological pathway underlying the association between sleep and obesity in children at-risk for obesity

Adiposity and cardiac autonomic function in children with a family history of obesity

PURPOSE

Data on associations between adiposity and heart rate variability (HRV) in prepubertal children are limited. We examined the associations between adiposity indices and HRV, independent of lifestyle behaviors, comparing multiple indicators of adiposity, and explored differences between boys and girls.

METHODS

Data stem from 469 participants of the QUALITY cohort (630 children aged 8-10 years with a parental history of obesity). Adiposity indices included waist-to-height ratio, body mass index (BMI) percentiles and categories (overweight, obesity), dual-energy x-ray absorptiometry (DEXA) defined fat mass percentage and android/gynoid ratio. HRV indices in the frequency and the spectral domain were derived from a daytime 3-h Holter recording. Multivariable linear regression models were adjusted for age, sex, Tanner stage, physical activity, screen time, and fitness. Interactions between sex and adiposity were tested.

RESULTS

Greater adiposity was associated with decreased parasympathetic modulation and increased sympathetic dominance. Waist-to-height ratio was associated with lower parasympathetic activity: root mean square of the successive differences (RMSSD) [B =  -23.32, 95% confidence interval (CI) -42.42, -4.22], pNN50 (B =  -16.93, 95% CI - 28.58, - 5.27), LF/HF ratio (B = 1.83, 95% CI 0.97-2.70). Patterns of association were similar for android/gynoid ratio. Overweight was not associated with altered HRV. Obesity was negatively associated with RMSSD and pNN50 and positively with LF/HF ratio. Greater fat mass percentage was associated with lower RMSSD, pNN50, and HF, and increased LF/HF ratio. There were no differences between boys and girls.

CONCLUSIONS

Specific markers of adiposity relate to altered HRV in childhood, with waist-to-height ratio being potentially a more relevant marker of HRV than BMI and more pragmatic than percent body fat.

TRIAL REGISTRATION

NCT03356262, 11 November 2017.

Remote Monitoring of Sympathovagal Imbalance During Sleep and Its Implications in Cardiovascular Risk Assessment: A Systematic Review

Nocturnal sympathetic overdrive is an early indicator of cardiovascular (CV) disease, emphasizing the importance of reliable remote patient monitoring (RPM) for autonomic function during sleep. To be effective, RPM systems must be accurate, non-intrusive, and cost-effective. This review evaluates non-invasive technologies, metrics, and algorithms for tracking nocturnal autonomic nervous system (ANS) activity, assessing their CV relevance and feasibility for integration into RPM systems. A systematic search identified 18 relevant studies from an initial pool of 169 publications, with data extracted on study design, population characteristics, technology types, and CV implications. Modalities reviewed include electrodes (e.g., electroencephalography (EEG), electrocardiography (ECG), polysomnography (PSG)), optical sensors (e.g., photoplethysmography (PPG), peripheral arterial tone (PAT)), ballistocardiography (BCG), cameras, radars, and accelerometers. Heart rate variability (HRV) and blood pressure (BP) emerged as the most promising metrics for RPM, offering a comprehensive view of ANS function and vascular health during sleep. While electrodes provide precise HRV data, they remain intrusive, whereas optical sensors such as PPG demonstrate potential for multimodal monitoring, including HRV, SpO2, and estimates of arterial stiffness and BP. Non-intrusive methods like BCG and cameras are promising for heart and respiratory rate estimation, but less suitable for continuous HRV monitoring. In conclusion, HRV and BP are the most viable metrics for RPM, with PPG-based systems offering significant promise for non-intrusive, continuous monitoring of multiple modalities. Further research is needed to enhance accuracy, feasibility, and validation against direct measures of autonomic function, such as microneurography.

Weight Status, Autonomic Function, and Systemic Inflammation in Children with Obstructive Sleep Apnea

Children with obstructive sleep apnea (OSA) frequently experience chronic low-grade systemic inflammation, with the inflammasome playing a central role in OSA. This cross-sectional study evaluated the relationship between weight status, autonomic function, and systemic inflammation in a cohort of 55 children with OSA, predominantly boys (78%) with an average age of 7.4 ± 2.2 years and an apnea-hypopnea index of 14.12 ± 17.05 events/hour. Measurements were taken of body mass index (BMI), sleep heart-rate variability, morning circulatory levels of interleukin-1β, interleukin-1 receptor antagonist, and interleukin-6, and tumor necrosis factor-α, anthropometry, and polysomnography. Multiple linear regression modeling showed that an apnea-hypopnea index was significantly associated with BMI, the standard deviation of successive differences between normal-to-normal intervals during N3 sleep, and the proportion of normal-to-normal interval pairs differing by more than 50 ms during rapid-eye-movement sleep. A moderated mediation model revealed that interleukin-1 receptor antagonist levels mediated the association between BMI and interleukin-6 levels, with sympathovagal balance during N3 sleep and minimum blood oxygen saturation further moderating these relationships. This study highlights the complex relationships between BMI, polysomnographic parameters, sleep heart-rate-variability metrics, and inflammatory markers in children with OSA, underlining the importance of weight management in this context.

Sleep duration and quality are associated with health-related quality of life in adults aged 60 years and older

BACKGROUND

The current study aimed to determine the association between sleep duration and quality with health-related quality of life (HRQoL) among the Iranian older persons.

METHODS

This study was conducted on a representative sample of 3452 Iranian older people (≥ 60 years) who participated in the Iranian Longitudinal Study on Ageing (IRLSA) launched in Neyshabur (Razavi Khorasan province, northeastern Iran). The Persian versions of 12-Item Short Form Survey (SF-12) and Pittsburgh Sleep Quality Index (PSQI) were utilized to measure the level of HRQoL and the level of sleep duration and quality, respectively. Multiple linear regression model was performed to analyze the data and clarify the independent association of sleep duration and quality with HRQoL.

RESULTS

More than half of the study population (52.4%) suffered from poor sleep quality. 57.3% and 3.9% of individuals were short sleepers (< 7 h) and long sleepers (equal or more than 9 h), respectively. The total score of HRQoL was achieved 65.87 ± 20.55. After adjusting the covariates, the results indicated that short sleep duration was negatively associated with HRQoL (P < 0.05), whereas no significant associations were found between long sleep duration and HRQoL (P > 0.05). Interestingly, the results of multiple linear regression model revealed a significant negative association between poor sleep quality and HRQoL (P < 0.001).

CONCLUSION

The current study confirmed that short sleep duration and poor sleep quality were independently associated with lower HRQoL in the older persons. Therefore, interventional courses should be planned to enrich sleep-related healthcare and general HRQoL in the older persons.

Is poor sleep quality associated with lipid profile in elderly population? Finding from Iranian Longitudinal Study on Ageing

BACKGROUND

Abnormal lipid profile as one of reversible cardiovascular disease risk factors might be affected by poor sleep quality.

AIM

This study aimed to assess the association between poor sleep quality and serum concentration of lipid profile in Iranian elderly population.

METHODS

The study was performed on a representative sample of 3452 Iranian older people (≥60 years) who contributed in the Iranian Longitudinal Study on Ageing (IRLSA). Sleep quality was measured through the validated Persian version of Pittsburgh Sleep Quality Index (PSQI). Fasting blood samples were collected from the participants to measure plasma levels lipid profile. We used multiple linear regression model to evaluate the independent association of poor sleep quality with lipid profile.

RESULTS

The mean age of participants was 68.0±6.7 years and 52.5% of them were male. In total, 52.4% of study population reported poor sleep quality (PSQI>5). Mean serum concentration of triglycerides (TG), total cholesterol (TC), low-density lipoprotein cholesterol (LDL-C), and high-density lipoprotein cholesterol (HDL-C) was 143.2±74.2 mg/dl, 195.6±43.2 mg/dl, 112.9±31.0 mg/dl, and 57.3±12.4 mg/dl, respectively. Poor sleep quality was significantly associated with serum levels of TG (β=17.85; P=0.006), LDL-C (β=5.45; P=0.039) and HDL-C (β=-2.13; P=0.039) after adjusting for studied covariates.

CONCLUSION

Our study illustrates that poor sleep quality is a risk factor for poorer lipid profile. Therefore, early behavioral or pharmacological interventions that improve sleep quality are necessary to modify lipid profile in elderly population.

Association between night sleep latency and hypertension: A cross-sectional study

Sleep disorders have been shown to increase the risk of hypertension, while the relationship between night sleep latency and hypertension is less well-known. We aimed to investigate the association between night sleep latency and hypertension, as well as related sleep factors by gender in the Chinese population. We conducted a cross-sectional study of the relationship between night sleep latency and hypertension. The sample size included 619 consecutive hospitalized patients (M/F: 302/317, 64.01 ± 12.27 years). T test, Chi-square test, and ANOVA were performed to analyze baseline data and intergroup comparisons. Spearman correlation analysis was performed to find the interrelationships. Multivariate logistic regression analysis was performed to adjust for covariables. The findings showed hypertension patients had longer night sleep latency (P < .001). After adjusting for confounding factors, night sleep latency was positively correlated with hypertension in both men and women (odds ratio: 1.065, 95% confidence interval: 1.044-1.087). Spearman correlation analysis suggested that night sleep latency was positively correlated with systolic blood pressure (r = 0.186, P < .001), diastolic blood pressure (r = 0.136, P < .001), sleep initiation time (r = 0.091, P = .023), and global Pittsburg Sleep Quality Index score (r = 0.371, P < .001), was negatively correlated with sleep duration (r = -0.186, P < .001), sleep time on weekdays (r = -0.183, P < .001), and sleep time on weekends (r = -0.179, P < .001). Longer night sleep latency was associated with an increased risk of hypertension in men and women, which might involve the pathological progression of hypertension along with other sleep factors.

Association between Poor Quality of Sleep and Metabolic Syndrome in Ghanaian University Students: A Cross-Sectional Study

Aim. This study aimed to determine the association between quality of sleep and metabolic syndrome (MetS) and physical activity level in young adults at the University of Ghana. Method. In a cross-sectional design, 340 university students, aged between 20-30 years were recruited. Quality of sleep was assessed using the Pittsburgh Sleep Quality index (PSQI) and physical activity with the short form of the International Physical Activity Questionnaire (IPAQ-SF). Poor quality of sleep was defined as a global PSQI score>5 and low physical activity level as those not meeting the criteria for vigorous-moderate physical activity. Anthropometric features and blood pressures were measured, and fasting blood samples were collected from the participants to measure plasma levels of glucose, lipid profile, urea, and creatinine. MetS was defined using the Joint Scientific Statement criteria. Results. In our study population of young adults from Ghana, the prevalence of poor quality of sleep as measured by PSQI was 54.1%, and MetS was 12.4%. MetS was associated with poor quality of sleep in females [ $\text{OR}\left(95\%\text{CI}\right)=2.11$ (1.04–4.25), $p=0.038$ ] and entire study participants [2.18 (1.09–4.37) $p=0.029$ ] in both crude and adjusted models; no association was found in male participants. Low physical activity status was not associated with poor sleep status. Obesity [1.32 (1.02–3.56), $p=0.043$ ], but not overweight [0.99 (0.58–2.34), $p=0.862$ ], was associated with poor quality of sleep. Conclusion. Young adults in a Ghanaian university have a high prevalence of poor quality of sleep and is associated with MetS and obesity. Physical activity status was not associated with poor quality of sleep.

Effects of Aerobic Exercise on the Serum Leptin Level and Heart Rate Variability in the Obese Girl Children

Objective

The present study examined the effects of a 16-week aerobic exercise (AE) on the serum leptin level and heart rate variability (time domain and frequency domain) in the obese girl children and correlation coefficients of changes between the serum leptin level and heart rate variability after a 16-week AE intervention.

Methods

36 participants were randomly assigned to either aerobic exercise (AE, n = 18) or obese group (n = 18). The obese girl children in the AE group conducted a 16-week (4 times per week and 60 min per time) exercise protocols, and the obese group did not perform regular physical training during 16 weeks of study. Then, the serum leptin level and HRV (time domain and frequency domain) were measured in all subjects before and after AE intervention.

Results

(1) After 16-week AE intervention, compared with pre-exercise, LF/HF decreased (P < 0.05), HF, SDNN, and RMSSD significantly increased (P < 0.05 and P < 0.01), and there was no significant difference in LF (P > 0.05) in the AE group. Nevertheless, there was no significant change before and after the test in the serum leptin level and HRV of the obese group (P > 0.05, respectively). (2) After 16-week AE intervention, compared with the obese group, SDNN and HF significantly increased (P < 0.05, respectively), LF/HF significantly decreased (P < 0.05) in the AE group, but there was no significant difference in RMSSD and LF between the obese group and AE group. (3) The reduction variables of the serum leptin level before and after the AE intervention are positively correlated with the reduction in the LF/HF (r = 0.478, P < 0.05) and negatively correlated with the increasing in the RMSSD (r = -0.482, P < 0.05). But there is no significant association between the reduction in the serum leptin level and the change of LF, HF, and SDNN (P > 0.05, respectively).

Conclusion

16-week AE significantly reduced the serum leptin level and improved cardiac autonomic function in the obese girl children. Moreover, the reduction in the serum leptin level was associated with the increase in parasympathetic activation and improved sympathetic-vagus balance after AE intervention. More research is needed to see whether the effect of exercise on leptin levels in obese girl children can reduce the risk of cardiovascular disease in adulthood.

Effect of COVID-19 Lockdown on Young Egyptian Soccer Players

The present study was designed to highlight the physical and psychological health hazards that a young Egyptian soccer team faced during the first COVID-19 wave lockdown. The study included 37 young Egyptian male soccer players. History taking and anthropometric measurements were taken. Two questionnaires were filled covering the athletes’` sleep habits and quality of life (QoL). Finally, the mothers were asked to fill in a questionnaire concerned with depression, anxiety, and stress. More than 50% of the enrolled athletes gained weight during the lockdown especially those without compliance to home exercises. The mothers’ anxiety score correlated positively with the increased body mass index (BMI) of the athletes. The athletes mean QoL Score worsened significantly and significant negative correlation was found between the increased BMI and the change of QoL. The increased BMI was significantly reported among the athletes who didn’t do home exercises and had a negative correlation with their QoL change throughout the lockdown. The mothers’ anxiety had a possible reflection on their youngsters’ weight gain. These findings highlight the need for weight control when outdoors physical activity is restricted during pandemics with better compliance to home exercising schedules and less screen time.

A systematic review of the association between sleep health and stress biomarkers in children

Sleep is intimately linked with the stress response system. While the evidence for this connection has been systematically reviewed in the adult literature, to our knowledge no studies have examined this relationship in young children. Recent scientific interest in understanding the effects of adverse environments in early childhood, including an emphasis on understanding the role of sleep, highlights the importance of synthesizing the current evidence on the relationship between sleep and the stress response system in early childhood. The aim of this systematic review is to examine the relationship between sleep health and biomarkers of physiologic stress (neuroendocrine, immune, metabolic, cardiovascular) in healthy children ages 0-12 y. Following PRISMA guidelines, we identified 68 empirical articles and critically reviewed and synthesized the results across studies. The majority of studies included school-age children and reported sleep dimensions of duration or efficiency. Overall, evidence of associations between sleep health and stress biomarkers was strongest for neuroendocrine variables, and limited or inconsistent for studies of immune, cardiovascular, and metabolic outcomes. Gaps in the literature include prospective, longitudinal studies, inclusion of children under the age of 5 y, and studies using objective measures of sleep.

Sex-Dependent Dyslipidemia and Neuro-Humoral Alterations Leading to Further Cardiovascular Risk in Juvenile Obesity

Objective: Childhood obesity is a growing concern as the World Health Organization (WHO) states that ~10% of adolescents worldwide are overweight or obese. This condition is the reflex of energy imbalance between the calories consumed and those expended. Sex-related responses associated with dyslipidemia, hormonal alterations, and neuro-humoral disruptions in childhood obesity are the focus of the present investigation. Methods: Ninety-two Brazilian adolescents were enrolled and divided between obese and eutrophic groups. Obesity was assessed using body mass index Z-score according to age and weight. Anthropometrical analyses, blood pressure, blood lipids, metabolism-regulating hormones, and neuropeptides were carried out. Results: Systolic blood pressure was higher in female and male patients with obesity. Obese females presented alterations in lipid profile and an augment of cardiovascular disease prediction ratios TC/HDL, TG/HDL, LDL/HDL, and VLDL/HDL. The levels of leptin, GIP, and neuropeptide showed sex-dimorphism in obesity. The obese adolescents presented increased levels of circulating insulin, c-peptide, amylin, glucagon, and GLP-1. Correlation analysis showed significant linearity between body mass index, blood pressure, lipids, lipoproteins, hormones, and neuropeptides content. Conclusions: Our data support an existing link associating hypertension, dyslipidemia, and neuro-hormonal imbalance in childhood obesity. We also described a sex-dependent pattern in childhood obesity-associated dyslipidemia and blood pressure in female patients with obesity solely.

Cardiac vagal imbalance to the isometric sustained weight test in adolescents with emotional eating behavior

PURPOSE

To assess the relationship between emotional eating behavior and heart rate variability in Spanish adolescents during an isometric exercise test.

METHODS

Participants included 52 adolescents aged between 13 and 18 years old. Heart rate was continuously recorded at rest (2 minutes) and during the sustained weight test (2 minutes). Linear and nonlinear methods of heart rate variability were assessed and related to the emotional eating behavior divided in two clusters.

RESULTS

Statistically significant differences were observed in linear and non-linear parameters of heart rate variability comparing rest and sustained weight test. An increase in the value of emotional eating in overweight adolescents was founded. During the sustained weight test, there were differences between the two emotional eating clusters regarding the variables peak high frequency power, normalized low frequency power, normalized high frequency power, low frequency/high frequency ratio, and sample entropy. A positive correlation between the emotional eating behavior and the peak high frequency power was observed, though the prediction capacity of the high frequency waves is low it is observed that there is a good fit to the regression line.

CONCLUSION

Results of this study shows that there was a relationship between vagal tone and emotional eating behavior in adolescents during an isometric exercise, with excessive parasympathetic predominance and sympathetic withdrawal during a physical effort.

Night-time cardiac autonomic modulation as a function of sleep-wake stages is modified in otherwise healthy overweight adolescents

OBJECTIVE

Even though sympathetic dominance during the daytime period is well known, currently, scarce data exist on autonomic nervous system (ANS) regulation during sleep in pediatric obesity. We aimed to evaluate sleep cardiac ANS regulation in normal-weight (NW) and overweight and obese (OW) adolescents.

PATIENTS/METHODS

In this study, 60 healthy adolescents (15.7 ± 0.7 years) belonging to a birth cohort since infancy were classified based on body mass index percentiles criteria as: OW (N = 27) or NW (N = 33). Sleep was evaluated by polysomnography (PSG) during two consecutive in-lab overnight sessions. Non-rapid eye movement (non-REM) sleep stages (stages 1, 2, and slow-wave sleep [SWS]), rapid eye movement (REM) sleep, and wakefulness (Wake) were scored. R-waves were detected automatically in the electrocardiographic (ECG) signal. An all-night heart rate variability analysis was conducted in the ECG signal, with several time- and frequency-domain measures calculated for each sleep-wake stage. Sleep time was divided into thirds (T1, T2, T3). The analysis was performed using a mixed-effects linear regression model.

RESULTS

Sleep organization was comparable except for reduced REM sleep percentage in the OW group (p < 0.04). Shorter R-R intervals were found for all sleep stages in the OW group; time-domain measured standard deviation of all R-R intervals (RRSD) was lower during stage 2, SWS and REM sleep (all p < 0.05). The square root of the mean of the sum of the squares of differences between adjacent R-R intervals (RMSSD) was also lower only during wake after sleep onset (WASO) in T1 and T3 (p < 0.05). The OW group had increased very low- and low-frequency (LF) power during WASO (in T1 and T2), and LF power during stage 2 and REM sleep (in T2). During WASO in the OW group, high-frequency (HF) power was lower (in T1 and T2), and LF/HF ratio was higher (in T2, p < 0.007).

CONCLUSIONS

Several sleep-stage-dependent changes in cardiac autonomic regulation characterized the OW group. As sleep-related ANS balance was disturbed in the absence of concomitant metabolic alterations in this sample of otherwise healthy OW adolescents, their relevance for pediatric obesity should be further explored throughout development.

Sex- and Age-Dependent Differences in Autonomic Nervous System Functioning in Adolescents

PURPOSE

We assessed sex- and age-dependent differences in a cross-sectional analysis of cardiac autonomic nervous system (ANS) regulation during sleep in adolescents.

METHODS

Nocturnal heart rate (HR) and heart rate variability (HRV) metrics, reflecting ANS functioning, were analyzed across the night and within undisturbed rapid eye movement (REM) and non-REM sleep in 149 healthy adolescents (12-22 years; 67 female) from the National Consortium on Alcohol and Neurodevelopment in Adolescence.

RESULTS

Nocturnal HR was slower in older, more pubertally advanced boys than in younger boys. In girls, HR did not vary according to age or maturity, although overall HRV and vagal modulation declined with age. Although younger boys and girls had similar HR, the male-female HR difference increased by ~2.4 bpm every year (p < .01, higher in older girls). Boys and girls showed expected increases in total HRV across the night but this within-night "recovery" was blunted in girls compared with boys (p < .05). Also, the non-REM and REM difference in HR was greater in girls (p < .01). Models exploring a role of covariates (sleep, mood, reproductive hormones, activity) in influencing HR and HRV showed few significant effects, apart from sedentary activity (higher in older girls), which partially mediated the sex × age interaction in HR.

CONCLUSIONS

Sex-related differences in cardiac ANS function emerge during adolescence. The extent to which sex-age divergences in ANS function are adaptive or reflect underlying sex-specific vulnerability for the development of psychopathology and other health conditions in adolescence needs to be determined.

Overweight in youth and sleep quality: is there a link?

OBJECTIVE

Overweight seems to be related to a higher prevalence of sleep disturbances. Decreased sleep duration and altered sleep quality are risk factors for obesity. Our aim was to compare the sleep pattern of overweight children with that of a matched control group and assess the relationship between sleep quality and obesity.

MATERIALS AND METHODS

Retrospective cohort study comparing 41 overweight children with a normal-weight control group, both submitted to polysomnography. The samples were matched for age, sex, and apnea-hypopnea index. Body mass index (BMI) z-scores were calculated using World Health Organization (WHO) growth charts. Insulin resistance in the study group was determined using the homeostatic model assessment for insulin resistance (HOMA-IR). Sleep patterns were compared. The statistical analysis was performed using SPSS® version 21.

RESULTS

The mean age (± standard deviation) of the population was 10 ± 3.4 years (min. 5 years; max. 17 years). Fifty-six percent of the participants in both groups were girls. N3% was lower in the study group (18.95 ± 6.18%) compared with the control group (21.61 ± 7.39%; t (40) = 2.156, p = 0.037). We found a correlation in the study group between HOMA-IR and N3% (Rs = -0.434, p = 0.008).

CONCLUSION

The present study suggests a link between overweight/obesity and altered sleep quality due to compromised non-rapid eye movement sleep, an indirect marker of sleep quality. There was also a link between slow-wave sleep duration and insulin resistance. We must find a strategy to provide adequate slow-wave sleep duration to reduce the obesity epidemic at young ages. Further research is needed.

Trajectories of sleep and cardiac sympathetic activity indexed by pre-ejection period in childhood

Fragmented and insufficient sleep has been implicated in disrupted autonomic nervous system activity during resting state conditions in typically developing children. Towards explication of these relations over development, the current study tested reciprocal relations between the development of sleep parameters (efficiency, duration, latency) and cardiac sympathetic nervous system (SNS) activity indexed by pre-ejection period (PEP) during waking-resting state conditions throughout middle and late childhood. Whether sleep derives changes in PEP or vice versa was examined. A longitudinal design was employed and latent growth modelling was used to examine the research questions. During the first assessment, 282 children aged 9.44 years (65% European American, 35% African American) participated. Two more assessments followed, with a 1-year lag between consecutive study waves. Sleep was examined with 7 nights of actigraphy in the child's home. Controlling for many potential confounds (sex, race/ethnicity, body mass index and family socioeconomic status), higher sleep efficiency and more sleep minutes predicted increases in PEP (less SNS activity) over 3 years. PEP did not predict changes in sleep efficiency or duration over time and there were no significant effects for sleep latency. Findings highlight the probable direction of effects between these two key bioregulatory systems. High levels of cardiac SNS activity are associated with many negative health outcomes, and thus these findings may have important implications.

Advancing a biopsychosocial and contextual model of sleep in adolescence: a review and introduction to the special issue

Sleep problems in adolescence have been identified as an international public health issue. Over the past few decades, notable advances have been made in our understanding of the patterns and consequences of sleep in adolescence. Despite these important gains, there is much about the role of sleep in adolescence that remains to be understood. This Special Issue brings together studies that examine sleep as it specifically pertains to adolescent development and adjustment. In this introductory article, we argue for the importance of grounding the study of sleep and adolescence in developmental science and a developmental psychopathology framework. First, a review of the literature is used to outline a biopsychosocial and contextual model of sleep in adolescence. Second, attention-deficit/hyperactivity disorder (ADHD) is used as an exemplar of the proposed model given the pervasiveness of sleep problems among youth with ADHD and the likelihood that sleep problems and ADHD symptoms are interconnected in complex ways. Finally, a brief introduction to the empirical articles included in the Special Issue is provided, with particular attention given to how these articles fit within the proposed biopsychosocial and contextual model. Along with the framework proposed in this article, the studies included in this Special Issue advance the current literature and point to critical directions for future research.