Salivary melatonin rhythm as a marker of the circadian system in healthy children and those with attention-deficit/hyperactivity disorder

The circadian system: A neglected player in neurodevelopmental disorders

Patients with neurodevelopmental disorders, such as autism spectrum disorder, often display abnormal circadian rhythms. The role of the circadian system in these disorders has gained considerable attention over the last decades. Yet, it remains largely unknown how these disruptions occur and to what extent they contribute to the disorders' development. In this review, we examine circadian system dysregulation as observed in patients and animal models of neurodevelopmental disorders. Second, we explore whether circadian rhythm disruptions constitute a risk factor for neurodevelopmental disorders from studies in humans and model organisms. Lastly, we focus on the impact of psychiatric medications on circadian rhythms and the potential benefits of chronotherapy. The literature reveals that patients with neurodevelopmental disorders display altered sleep-wake cycles and melatonin rhythms/levels in a heterogeneous manner, and model organisms used to study these disorders appear to support that circadian dysfunction may be an inherent characteristic of neurodevelopmental disorders. Furthermore, the pre-clinical and clinical evidence indicates that circadian disruption at the environmental and genetic levels may contribute to the behavioural changes observed in these disorders. Finally, studies suggest that psychiatric medications, particularly those prescribed for attention-deficit/hyperactivity disorder and schizophrenia, can have direct effects on the circadian system and that chronotherapy may be leveraged to offset some of these side effects. This review highlights that circadian system dysfunction is likely a core pathological feature of neurodevelopmental disorders and that further research is required to elucidate this relationship.

Sleep problems and circadian rhythm functioning in autistic children, autism with co-occurring attention deficit hyperactivity disorder, and typically developing children: A comparative study

LAY ABSTRACT

Sleep problems are common in autism spectrum disorder (ASD) and different factors can contribute to its occurrence in this population. Misalignment of the biological clock (our circadian system) has been described as one possible explanation. While there is a body of research on sleep problems, relatively less is known about circadian functioning and the specific population of autistic children with co-occurring attention deficit hyperactivity disorder (ADHD). Using an ambulatory circadian monitoring (ACM) system, which resembles a common watch, we gathered sleep parameters and the different rhythms obtained from measuring motor activity, light exposure and distal temperature in 87 autistic children and adolescents, 27 of whom were diagnosed with co-occurring ADHD, and 30 neurotypical children and adolescents as a comparison group. Autistic children and, especially, those with co-occurring ADHD showed greater motor activity during sleep which would be worth studying in future projects which could better define this restless sleep. Of note, we observed an atypical pattern of wrist temperature, with higher values in neurotypical children, followed by autistic children and, ultimately, those with co-occurring ADHD. Temperature is one of the most valuable factors evaluated here as it is closely connected to sleep-wakefulness and the hormone melatonin. Its special pattern during day and nighttime would support the hypothesis of an atypical secretion of melatonin in autistic individuals which would also link with the higher presence of sleep problems in this neurodevelopmental condition.

Association between the plasma concentration of melatonin and behavioral temperament in horses

Aggression in horses may cause serious accidents during riding and non-riding activities. Hence, predicting the temperament of horses is essential for selecting suitable horses and ensuring safety during the activity. In certain animals, such as hamsters, plasma melatonin concentrations have been correlated with aggressive behavior. However, whether this relationship applies to horses remains unclear. To address this research gap, this study aimed to evaluate differences in the plasma melatonin concentrations among horses of different breeds, ages, and sexes and examine the correlation between plasma melatonin concentrations and the temperament of the horses, including docility, affinity, dominance, and trainability. Blood samples from 32 horses were collected from the Horse Industry Complex Center of Jeonju Kijeon College. The docility, affinity, dominance, and trainability of the horses were assessed by three professional trainers who were well-acquainted with the horses. Plasma melatonin concentrations were measured using an enzyme-linked immunosorbent assay. The consequent values were compared between the horses of different breeds, ages, and sexes using a three-way analysis of variance and least significant difference post hoc test. Linear regression analysis was employed to identify the relationship between plasma melatonin concentrations and docility, affinity, dominance, and trainability. The results showed that the plasma melatonin concentrations significantly differed with breeds in Thoroughbred and cold-blooded horses. However, there were no differences in the plasma melatonin concentrations between the horse ages and sexes. Furthermore, plasma melatonin concentrations did not exhibit a significant correlation with the ranking of docility, affinity, dominance, and trainability.

Development and Validation of an Ultrasensitive LC-MS/MS Method for the Quantification of Melatonin in Human Saliva

A growing body of literature describes the potential effects of circadian disruption on human health. Indeed, psychiatric diseases, metabolic syndrome, and cancers may be linked to disturbance of the circadian rhythm. Currently, the best practice to assess circadian rhythm is the measurement of melatonin levels. Our goal was thus to develop and validate a highly sensitive LC-MS/MS method to follow salivary melatonin levels throughout the day and night. Our method reached a lower limit of the measuring interval (LLMI) of 0.8 pg/mL. To our knowledge, it is the most sensitive method allowing quantitation of melatonin in saliva. Saliva, obtained from passive drooling or salivette, was extracted by an efficient and quick liquid-liquid extraction with no further cleanup needed. The method was validated according to the European Medicines Agency (EMA) guidelines and provided excellent results regarding accuracy, precision, linearity, selectivity, and specificity. Comparison between radioimmunoassay and our method was performed and showed differences at low levels, most likely due to cross-reactivity with other indols. To assess daytime melatonin levels in humans, salivary melatonin levels of ten volunteers were monitored throughout the day and showed lower daytime levels than reported in previous studies.

Associations of meeting 24-h movement behavior guidelines with cognitive difficulty and social relationships in children and adolescents with attention deficit/hyperactive disorder

BACKGROUND

Evidence-based 24-h movement behavior (24-HMB) guidelines have been developed to integrate recommendations for the time spent on physical activity, sedentary behavior, and sleep. For children and adolescents, these 24-HMB guidelines recommend a maximum of two hours of recreational screen time (as part of sedentary behavior), a minimum of 60 min per day of moderate to vigorous physical activity (MVPA), and an age-appropriate sleep duration (9-11 h for 5 to 13-year-olds; 8-10 h for 14 to 17-year-olds). Although adherence to the guidelines has been associated with positive health outcomes, the effects of adhering to the 24-HMB recommendations have not been fully examined in children and adolescents with attention eficit/hyperactive disorder (ADHD). Therefore, this study examined potential associations between meeting the 24-HMB guidelines and indicators of cognitive and social difficulties in children and adolescents with ADHD.

METHODS

Cross-sectional data on 3470 children and adolescents with ADHD aged between 6 and 17 years was extracted from the National Survey for Children's Health (NSCH 2020). Adherence to 24-HMB guidelines comprised screen time, physical activity, and sleep. ADHD-related outcomes included four indicators; one relating to cognitive difficulties (i.e., serious difficulties in concentrating, remembering, or making decisions) and three indicators of social difficulties (i.e., difficulties in making or keeping friends, bullying others, being bullied). Logistic regression was performed to determine the associations between adherence to 24-HMB guidelines and the cognitive and social outcomes described above, while adjusting for confounders.

RESULTS

In total, 44.8% of participants met at least one movement behavior guideline, while only 5.7% met all three. Adjusted logistic regressions further showed that meeting all three guidelines was associated with lower odds of cognitive difficulties in relation to none of the guidelines, but the strongest model included only screen time and physical activity as predictors (OR = 0.26, 95% CI 0.12-0.53, p < .001). For social relationships, meeting all three guidelines was associated with lower odds of difficulty keeping friends (OR = 0.46, 95% CI 0.21-0.97, p = .04) in relation to none of the guidelines. Meeting the guideline for screen time was associated with lower odds of being bullied (OR = 0.61, 95% CI 0.39-0.97, p = .04) in relation to none of the guidelines. While screen time only, sleep only and the combination of both were associated with lower odds of bullying others, sleep alone was the strongest predictor (OR = 0.44, 95% CI 0.26-0.76, p = .003) in relation to none of the guidelines.

CONCLUSION

Meeting 24-HMB guidelines was associated with reduced likelihood of cognitive and social difficulties in children and adolescents with ADHD. These findings highlight the importance of adhering to healthy lifestyle behaviors as outlined in the 24-HMB recommendations with regard to cognitive and social difficulties in children and adolescents with ADHD. These results need to be confirmed by longitudinal and interventional studies with a large sample size.

Development and Initial Validation of the Assessment of Sleep Environment (ASE): Describing and Quantifying the Impact of Subjective Environmental Factors on Sleep

The purpose of this study was to develop and test the reliability and validity of a 13-item self-report Assessment of Sleep Environment (ASE). This study investigates the relationship between subjective experiences of environmental factors (light, temperature, safety, noise, comfort, humidity, and smell) and sleep-related parameters (insomnia symptoms, sleep quality, daytime sleepiness, and control over sleep). The ASE was developed using an iterative process, including literature searches for item generation, qualitative feedback, and pilot testing. It was psychometrically assessed using data from the Sleep and Healthy Activity Diet Environment and Socialization (SHADES) study (N = 1007 individuals ages 22-60). Reliability was determined with an internal consistency and factor analysis. Validity was evaluated by comparing ASE to questionnaires of insomnia severity, sleep quality, daytime sleepiness, sleep control, perceived stress, and neighborhood disorder. The ASE demonstrated high internal consistency and likely reflects a single factor. ASE score was associated with insomnia symptoms (B = 0.09, p < 0.0001), sleep quality (B = 0.07, p < 0.0001), and sleep control (B = -0.01, p < 0.0001), but not daytime sleepiness. The ASE was also associated with perceived stress (B = 0.20, p < 0.0001) and neighborhood disorder (B = -0.01, p < 0.0001). Among sleep environment factors, only smell was not associated with sleep quality; warmth and safety were negatively associated with sleepiness; and of the sleep environment factors, only light/dark, noise/quiet, and temperature (warm/cool) were not associated with insomnia symptoms. The ASE is a reliable and valid measure of sleep environment. Physical environment (light, temperature, safety, noise, comfort, humidity, and smell) was associated with insomnia symptoms and sleep quality but not sleepiness.

Clock Genes Profiles as Diagnostic Tool in (Childhood) ADHD—A Pilot Study

Attention deficit hyperactivity disorder (ADHD) is a very common disorder in children and adults. A connection with sleep disorders, and above all, disorders of the circadian rhythm are the subject of research and debate. The circadian system can be represented on different levels. There have been a variety of studies examining 24-h rhythms at the behavioral and endocrine level. At the molecular level, these rhythms are based on a series of feedback loops of core clock genes and proteins. In this paper, we compared the circadian rhythms at the behavioral, endocrine, and molecular levels between children with ADHD and age- and BMI-matched controls, complementing the previous data in adults. In a minimally invasive setting, sleep was assessed via a questionnaire, actigraphy was used to determine the motor activity and light exposure, saliva samples were taken to assess the 24-h profiles of cortisol and melatonin, and buccal mucosa swaps were taken to assess the expression of the clock genes BMAL1 and PER2. We found significant group differences in sleep onset and sleep duration, cortisol secretion profiles, and in the expression of both clock genes. Our data suggest that the analysis of circadian molecular rhythms may provide a new approach for diagnosing ADHD in children and adults.

Risk Factors for Attention Deficit Hypersensitivity Disorder in Children: A Systematic Review

BACKGROUND

Attention Deficit Hyperactivity Disorder (ADHD) is among the most prevalent childhood disorders. This condition is characterized by impulsive behaviour, restlessness, and lack of concentration. Various researchers have come up with diverse conclusions concerning the risk factors of ADHD OBJECTIVE: However, there is a need for a comprehensive review to understand the risk factors associated with the development of ADHD METHODS: For this, Preferred Reporting Items for Systematic Reviews (PRISMA), the methodology was used to extract the findings.

RESULTS

The finding suggests that there are a variety of risk factors associated with women which may be responsible for the development of ADHD among children. The main four risk factors are; antibiotics use in early life, insufficient omega 3 and 6 in the body; disruption of gut microbiota; irregular circadian rhythm. These factors, which are discussed in-depth in the review, include factors that affect the development of the brain in children.

CONCLUSION

This review concludes that a variety of risk factors may contribute to the development of ADHD. Further, this review highlights not only the importance of metabolic, physiological but also highlights the importance of biopsychological aspects which leads to the development of ADHD among children. Studies should be conducted to check the impact of such factors holistically to minimize the risk of ADHD.

A Systematic Review of Sleep and Circadian Rhythms in Children with Attention Deficit Hyperactivity Disorder

OBJECTIVE

Children and adults with ADHD often report sleep disturbances that may form part of the etiology and/or symptomatology of ADHD. We review the evidence for sleep changes in children with ADHD.

METHODS

Systematic review with narrative synthesis assessing sleep and circadian function in children aged 5 to 13 years old with a diagnosis of ADHD.

RESULTS

148 studies were included for review, incorporating data from 42,353 children. We found that sleep disturbances in ADHD are common and that they may worsen behavioral outcomes; moreover, sleep interventions may improve ADHD symptoms, and pharmacotherapy for ADHD may impact sleep.

CONCLUSION

Sleep disturbance may represent a clinically important feature of ADHD in children, which might be therapeutically targeted in a useful way. There are a number of important gaps in the literature. We set out a manifesto for future research in the area of sleep, circadian rhythms, and ADHD.

Longitudinal changes in sleep patterns and circadian rhythm metrics in preschool-age children from Northern Mexico

OBJECTIVES

To assess changes in sleep parameters and circadian rhythm metrics measured by actigraphy in preschool-aged children.

DESIGN

Longitudinal analysis over 1 year.

PARTICIPANTS

Ninety-four children living in Tijuana and Ensenada, Mexico.

MEASUREMENTS

Children wore accelerometers on the right hip for one continuous week at baseline and 1-year follow-up. Parents recorded child bedtime, waketime, and naps in sleep diaries. We used cosinor and nonparametric approaches to calculate circadian rhythm metrics.

RESULTS

At baseline, children had a mean age of 4.2 years, and 51.1% were girls. In multivariable models adjusted for age, gender, BMI category, parental education, household income and city, at follow-up children had significantly earlier waketimes (β = -7.99 minutes, p < .001) compared to baseline. Children also had lower sleep onset latency (β = -2.32 minutes, p = .057), and longer nighttime sleep (β = 9.38 minutes, p = .079), but these changes were not significant at the α < 0.05 level. We found significant increases in log relative amplitude (β = 0.017, p = .009), and decreases in log midline estimated statistic of rhythm (β = -0.084, p = .017) and log of the least active 5-hour period (β = -0.057, p = .010). When we adjusted for co-sleeping, we found significant decreases in the number of nighttime awakenings (β = -1.29, p = .011) but otherwise similar results. There were no other changes in sleep parameters or circadian rhythm metrics.

CONCLUSIONS

Mean increases in nighttime sleep and earlier wake times over one year were concomitant with decreases in overall activity levels and increases in circadian rhythm robustness. Co-sleeping was a predictor of sleep disturbances. This study provides longitudinal evidence regarding changes in sleep and circadian metrics in a sample of children from an under-researched sociodemographic group during an important, early life period.

Systems Biology Approaches and Precision Oral Health: A Circadian Clock Perspective

A vast majority of the pathophysiological and metabolic processes in humans are temporally controlled by a master circadian clock located centrally in the hypothalamic suprachiasmatic nucleus of the brain, as well as by specialized peripheral oscillators located in other body tissues. This circadian clock system generates a rhythmical diurnal transcriptional-translational cycle in clock genes and protein expression and activities regulating numerous downstream target genes. Clock genes as key regulators of physiological function and dysfunction of the circadian clock have been linked to various diseases and multiple morbidities. Emerging omics technologies permits largescale multi-dimensional investigations of the molecular landscape of a given disease and the comprehensive characterization of its underlying cellular components (e.g., proteins, genes, lipids, metabolites), their mechanism of actions, functional networks and regulatory systems. Ultimately, they can be used to better understand disease and interpatient heterogeneity, individual profile, identify personalized targetable key molecules and pathways, discover novel biomarkers and genetic alterations, which collectively can allow for a better patient stratification into clinically relevant subgroups to improve disease prediction and prevention, early diagnostic, clinical outcomes, therapeutic benefits, patient's quality of life and survival. The use of “omics” technologies has allowed for recent breakthroughs in several scientific domains, including in the field of circadian clock biology. Although studies have explored the role of clock genes using circadiOmics (which integrates circadian omics, such as genomics, transcriptomics, proteomics and metabolomics) in human disease, no such studies have investigated the implications of circadian disruption in oral, head and neck pathologies using multi-omics approaches and linking the omics data to patient-specific circadian profiles. There is a burgeoning body of evidence that circadian clock controls the development and homeostasis of oral and maxillofacial structures, such as salivary glands, teeth and oral epithelium. Hence, in the current era of precision medicine and dentistry and patient-centered health care, it is becoming evident that a multi-omics approach is needed to improve our understanding of the role of circadian clock-controlled key players in the regulation of head and neck pathologies. This review discusses current knowledge on the role of the circadian clock and the contribution of omics-based approaches toward a novel precision health era for diagnosing and treating head and neck pathologies, with an emphasis on oral, head and neck cancer and Sjögren's syndrome.

[Sleep and cognition in children and adolescents]

Sleep and cognition in children and adolescents Abstract. In this review, one of the most important functions of sleep was described: Its role in promoting cognitive processes in children and adolescents. Particularly, studies of older children and adolescents revealed that sleep interacts in a complex manner with cognitive performance. Moreover, it was shown that sleep supports long-term memory even in young children. This is true for many different long-term memory systems such as memory of factual information (declarative memory), language acquisition, and for reward-related learning, but less so for learning motor skills. Clinical implications arise from observing the consequences of sleep deficits in children and adolescents due to early school hours or due to clinical conditions like attention deficits hyperactive disorder (ADHD), sleep apnea syndrome or other sleep disturbances. Current research has only partially shown that the treatment of sleep problems also benefits cognitive and memory performance. Filling this gap remains an opportunity for further research.

Time-shifting effects of methylphenidate on daily rhythms in the diurnal rodent Arvicanthis ansorgei

People suffering of attention-deficit/hyperactivity disorder (ADHD) and treated with the psychostimulant methylphenidate (MPH) show sleep-wake cycle and daily rhythm alterations despite the beneficial effects of MPH on behavioral symptoms (i.e., hyperactivity, attention). In nocturnal rodents (i.e., mice), chronic exposure to MPH alters the neural activity of the circadian clock in the suprachiasmatic nucleus (SCN), behavioral rhythms, and the sleep-wake cycle. Here, we studied the effects of MPH on daily rhythms of behavior and body temperature of the diurnal rodent Arvicanthis ansorgei. Under a light-dark cycle, chronic exposure to MPH in drinking water delayed the onset of both activity and body temperature rhythms. Interestingly, delays were larger when MPH access was restricted to the first 6 h of the light phase (i.e., activity phase) of the 24-h cycle. Since MPH effects are dependent on animal's fluid intake, in a last experiment, we controlled the time and dose of MPH delivery in Arvicanthis using an intraperitoneal perfusion method. Similarly to the experiment with MPH in drinking water, Arvicanthis showed a delay in the onset of general activity and body temperature when MPH infusions, but not vehicle, were during the first 6 h of the light phase. This study indicates that MPH alters daily rhythms in a time-dependent manner and proposes the use of a diurnal rodent for the study of the effects of MPH on the circadian clock. Knowing the circadian modulation on the effects of MPH in behavior could give new insights in the treatment of ADHD.

Sleep Disturbances in Child and Adolescent Mental Health Disorders: A Review of the Variability of Objective Sleep Markers

Sleep disturbances are often observed in child and adolescent mental health disorders. Although previous research has identified consistent subjective reports of sleep disturbances, specific objective sleep markers have not yet been identified. We evaluated the current research on subjective and objective sleep markers in relation to attention deficit hyperactivity disorders, autism spectrum disorders, anxiety and depressive disorders. Subjective sleep markers are more consistent than objective markers of actigraphy, polysomnography, and circadian measures. We discuss the causes of variability in objective sleep findings and suggest future directions for research.

Delayed Onset of Sleep in Adolescents With PAX6 Haploinsufficiency

OBJECTIVE

PAX6 haploinsufficiency ( +/-) can occur due to mutations involving only PAX6 in patients with isolated aniridia or as contiguous gene deletions in patients with Wilms tumor, aniridia, genitourinary anomalies, and range of developmental and intellectual disabilities syndrome. Given the role of PAX6 in pineal development and circadian regulation, adolescents with PAX6+/- may experience sleep-wake disturbances. The purpose of this observational study was to explore sleep-related phenotypes in adolescents with PAX6+/-.

METHODS

This study compared sleep phenotypes of nine subjects with PAX6+/- (aged 10-19 years) with previously published data on healthy adolescents ( n = 25, aged 10-18 years). Subjects completed the Cleveland Adolescent Sleepiness Questionnaire (CASQ), Patient Reported Outcomes Measurement Information System (PROMIS) Sleep Disturbance (v. 1.0; 8a), and PROMIS Sleep-Related Impairment (v. 1.0; 8b) Questionnaires and wore actigraphs for seven nights to record sleep patterns.

RESULTS

Total CASQ, PROMIS sleep-related impairment, and PROMIS sleep disturbance scores were not statistically different between the groups ( ps > .15). Actigraph data for lights off to sleep-onset time were found to be significantly higher in subjects with PAX6+/- versus the healthy comparison group (adjusted mean [95% confidence interval]: 20.1 min [8.1, 49.8] vs. 6.2 min [3.7, 10.4], respectively, p = .04).

CONCLUSION

Both adolescents with PAX6+/- and the healthy comparison group on average slept less than 8 hr/night, and overall sleep deprivation in adolescents may have masked differences between groups. This study used rare genetic disorders with biological vulnerability to sleep problems as a genotype-phenotype model. Knowledge of sleep-related phenotypes will assist in designing studies to manage sleep-related symptoms in adolescents.

ADHD and lifestyle habits in Czech adults, a national sample

BACKGROUND

Adult attention-deficit/hyperactivity disorder (ADHD) has been added as a diagnosis to the Diagnostic and Statistical Manual of Mental Disorders version 5 (DSM5) in 2013, thus making ADHD, which has been classically known as a childhood disorder, a life-long disorder. Those suffering from the condition show very specific behavioral traits, which manifest as lifestyle habits; they also show comorbidities that can be the symptoms and/or consequences of certain lifestyles.

MATERIALS AND METHODS

The targeted population was adults aged 18-65 years. The total sample was 1,012 (507 males and 505 females). The Adult ADHD Self-Report Scale (ASRS V. 1.1) was administered to evaluate the current symptoms of ADHD and a questionnaire regarding lifestyles that are pertinent to ADHD, exercise, drug use, and diet.

RESULTS

An ASRS score of 4-6 points was found in 11.4% of the male population and 9.7% of the female population (5-6 points indicate very high-intensity symptoms). A score of 6, the highest intensity of symptomatology, was found in 1.18% of males and 0.99% of females. Gender differences in scores were not statistically significant. In terms of self-reported lifestyles, we calculated an ordered logistic regression and the odds ratios of those with ASRS scores >4. Those with higher ASRS scores had higher rates of self-reported unhealthy lifestyles and poor diets with high consumption of sweets. We also ascertained a paradoxical finding that is not in line with the current literature on the disorder - lower rates of cigarette smoking among people with higher ADHD symptomatology.

CONCLUSION

Several specific lifestyles were found to be associated with higher ADHD symptoms such as poor diet and cannabis use. Other factors classically associated with the disorder such as cocaine addiction and nicotinism were either insignificant or surprisingly less prominent among the Czech sample. However, ADHD-prone respondents reported to be more physically active, which fits the clinical picture of hyperactivity but contrasts with literature that reports sedentary ADHD lifestyle.

Correcting delayed circadian phase with bright light therapy predicts improvement in ADHD symptoms: A pilot study

Attention-deficit/hyperactivity disorder (ADHD) is a common condition with comorbid insomnia reported in >70% of children and adults. These patients demonstrate delays in sleep-wake rhythms, nocturnal rise in melatonin, and early morning rise in cortisol. Given that standard psychopharmacologic treatments for ADHD often do not completely control symptoms in participants with circadian rhythm delay, we sought to test whether bright light therapy (BLT) advances circadian rhythms and further reduces ADHD symptoms over standard treatments. In addition to standard of care, participants with ADHD diagnosis underwent 1 week of baseline assessment followed by 2-weeks of 30-min morning 10,000-lux BLT beginning 3 h after mid-sleep time. Participants minimized overhead light after 4 p.m., wore an actigraphy watch, and recorded BLT time on daily sleep logs. Dim Light Melatonin Onset (DLMO) was assessed at baseline and after 2-week treatment. ADHD symptoms were measured by the ADHD-Rating Scales (ADHD-RS). BLT significantly advanced the phase of DLMO by 31 min [mean time (SEM), 20:36 (0:21) advanced to 20:05 (0:20)] and mid-sleep time by 57 min [4:37 (0:22) advanced to 3:40 (0:16); paired t-tests, p = 0.002 and 0.004, respectively). Phase advances (in DLMO or mid-sleep time) were significantly correlated with decreased ADHD-RS total scores (p = 0.027 and 0.044) and Hyperactive-Impulsive sub-scores (p = 0.014 and 0.013, respectively). Actigraphy analysis for a subset of 8 participants with significant DLMO phase advance revealed no significant changes in total sleep time, sleep efficiency, wake after sleep onset, or percent wake during sleep interval. This is the first successful use of BLT for advancing melatonin phase and improving ADHD symptoms in adults. BLT may be a complementary treatment for both delayed sleep timing and ADHD symptoms in adults.

The Prospective Association of the Diurnal Cortisol Rhythm With Sleep Duration and Perceived Sleeping Problems in Preschoolers: The Generation R Study

OBJECTIVE

Cortisol, the end product of the hypothalamic-pituitary-adrenal axis, plays an important role in modulating sleep. Yet, studies investigating the association between diurnal cortisol rhythm and sleep patterns in young children are scarce. We tested the hypothesis that the diurnal cortisol rhythm is associated with shorter sleep duration and more sleep problems across early childhood.

METHODS

This study was embedded in Generation R, a population-based cohort from fetal life onward. Parents collected saliva samples from their infant at five moments during day 1. In 322 infants aged 12 to 20 months, we determined the diurnal cortisol rhythm by calculating the area under the curve (AUC), the cortisol awakening response (CAR), and the diurnal slope. Sleep duration and sleep behavior were repeatedly assessed across ages of 14 months to 5 years. Generalized estimating equation models were used to assess related cortisol measures to sleep duration and sleep behavior.

RESULTS

The diurnal cortisol slope and the CAR, but not the AUC, were associated with sleep duration across childhood. Children with flatter slopes and children with a more positive CAR were more likely to have shorter nighttime sleep duration (β per nmol/L/h slope = -0.12, 95% confidence interval = -0.19 to -0.05, p = .001; β per nmol/L CAR = -0.01, 95% confidence interval = -0.02 to 0.00, p = .04). Cortisol measures did not predict sleep problems.

CONCLUSIONS

The present study suggests that a flatter diurnal cortisol slope and a more marked morning rise, which can indicate stress (or hypothalamic-pituitary-adrenal dysregulation), have a long-term association with sleep regulation.

ADHD, Lifestyles and Comorbidities: A Call for an Holistic Perspective - from Medical to Societal Intervening Factors

The review examines Attention Deficit Hyperactivity Disorder (ADHD in its Child and Adult form) and its various presentations (Hyperactive Impulsive, Inattentive, and Combined) with a particular focus on environmental (incl. social factors), lifestyles and comorbidities. It is argued that ADHD is best understood in a holistic and interactive context and a vast empirical literature is presented to illustrate the point: Environmental factors include stress in general as well as exposure to toxins (phthalates, bisphenol A). Social factors are illustrated by effects of social deprivation and seduction to unhealthy lifestyles. Maternal lifestyle during pregnancy is pointed out (particularly her exposure to nicotine, alcohol, caffeine, and drugs, even seemingly benign medications like acetaminophen), which all tend to be related to ADHD. Family environment is discussed with respect to protective effect of (mainly authoritative and autocratic) parenting styles. Societal factors include mainly economic and political issues: income inequality and poverty (low SES is an ADHD risk factor) and a growing moral dilemma between a humanistic effort to globally spread the knowledge of ADHD and the medicalization and commercialization of the disorder. The second part of the review is devoted to ADHD related lifestyles and resulting comorbidities (e.g., food addiction and obesity, substance abuse, electronic media dependencies and conduct and personality disorders). Although ADHD is a neurodevelopmental disorder, its assessment and treatment are also linked to environmental, behavioral and social factors and their interactions.

Sleep Problems as Predictors in Attention-Deficit Hyperactivity Disorder: Causal Mechanisms, Consequences and Treatment

Attention-deficit hyperactivity disorder (ADHD) is notorious for its debilitating consequences and early age of onset. The need for early diagnosis and intervention has frequently been underscored. Previous studies have attempted to clarify the bidirectional relationship between ADHD and sleep problems, proposing a potential role for sleep problems as early predictors of ADHD. Sleep deprivation, sleep-disordered breathing, and circadian rhythm disturbances have been extensively studied, yielding evidence with regard to their induction of ADHD-like symptoms. Genetic-phenotypic differences across individuals regarding the aforementioned sleep problems have been elucidated along with the possible use of these characteristics for early prediction of ADHD. The long-term consequences of sleep problems in individuals with ADHD include obesity, poor academic performance, and disrupted parent-child interactions. Early intervention has been proposed as an approach to preventing these debilitating outcomes of ADHD, with novel treatment approaches ranging from melatonin and light therapy to myofunctional therapy and adjustments of the time point at which school starts.

Sleep disturbances in adolescents with ADHD: A systematic review and framework for future research

BACKGROUND

Biological mechanisms underlying symptom and prognostic heterogeneity in Attention-Deficit/Hyperactivity Disorder (ADHD) are unclear. Sleep impacts neurocognition and daytime functioning and is disrupted in ADHD, yet little is known about sleep in ADHD during adolescence, a period characterized by alterations in sleep, brain structure, and environmental demands as well as diverging ADHD trajectories.

METHODS

A systematic review identified studies published prior to August 2016 assessing sleep in adolescents (aged 10-19years) with ADHD or participating in population-based studies measuring ADHD symptoms.

RESULTS

Twenty-five studies were identified (19 subjective report, 6 using actigraphy/polysomnography). Findings are mixed but overall suggest associations between sleep disturbances and 1) ADHD symptoms in the population and 2) poorer clinical, neurocognitive, and functional outcomes among adolescents with ADHD. Common limitations of studies included small or non-representative samples, non-standardized sleep measures, and cross-sectional methodology.

CONCLUSIONS

Current data on sleep in adolescent ADHD are sparse and limited by methodological concerns. Future studies are critical for clarifying a potential role of sleep in contributing to heterogeneity of ADHD presentation and prognosis. Potential mechanisms by which sleep disturbances during adolescence may contribute to worsened symptom severity and persistence of ADHD into adulthood and an agenda to guide future research are discussed.

Circadian rhythms and attention deficit hyperactivity disorder: The what, the when and the why

Attention deficit hyperactivity disorder (ADHD) is a common neurodevelopmental condition characterised by impulsivity, inattention and hyperactivity. Aside from these core psychopathologies, sleep disturbances are found to be highly comorbid with ADHD, and indeed dysregulated sleep may contribute to some of the symptoms of the disorder. It is not clear how sleep disturbances come to be so common in ADHD, but one putative mechanism is through the circadian timekeeping system. This system underpins the generation of near 24-hour rhythms in a host of physiological, behavioural and psychological parameters, and is a key determinant of the sleep/wake cycle. In this paper we review the evidence for sleep and circadian rhythm disturbance in ADHD, examine the possible mechanistic links between these factors and the disorder and discuss future directions through which the circadian clock can be targetted for ADHD symptom relief.

Increased urinary 6-hydroxymelatoninsulfate levels in attention deficit hyperactivity disorder diagnosed children and adolescent

There are some studies in attention deficit hyperactivity disorder (ADHD) which note altered circadian rhythms, suggesting abnormalities in melatonin physiology. In order to better characterize the possible melatonin alteration in ADHD, in this study we aimed to detect daytime, nighttime and 24 h levels of 6-hydroxymelatoninsulfate (6-OH MS) in the patients diagnosed with ADHD. Twenty-seven patients between 6 and 16 years-old, who had been diagnosed initially with ADHD, but without other physical and psychiatric disease history and who had not taken psychotropic pharmacotherapy for six months, plus 28 healthy volunteer controls, were included in the study. Urine samples were collected during the whole 24 h cycle, daytime and nighttime separately to assess the time-dependent excretion of the 6-OH MS, which is the main urine metabolite of melatonin. The Enzyme-Linked Immunosorbent Assay (ELISA) method was used for measuring the urine 6-OH MS level. Daytime (15.4 (8.9-24.8) ng/ml vs 6.9 (2.5-15.9) ng/ml, p=0.002), nighttime (102.9 (65.3-197.7) ng/ml vs 61.5 (37.2-114.4) ng/ml, p=0.012) and 24 h (54.1 (34.6-83.9) ng/ml vs 27.3 (14.3-48.9) ng/ml, p=0.000) 6-OH MS levels median (25p-75p) were found to be significantly higher in the ADHD group. After adjustment for age and sex, there was a statistically significant difference between the ADHD group (59.8 ± 4.9) and control group (33.8 ± 4.8) in 24-h 6-OH MS levels (F(1, 51)=13.673, p=.001, partial η2=.211). There was no relationship between 6-OH MS levels and Conners Parent Rating Scale short form subscale scores for the ADHD group. These findings indicate that melatonin production is increased in ADHD cases. Further research is needed to determine and thereby understand the mechanisms underlying the higher melatonin production, to assess the impact of altered melatonin on the pathophysiology of ADHD.

Moderate Changes in the Circadian System of Alzheimer's Disease Patients Detected in Their Home Environment

Alzheimer's disease (AD) is a neurodegenerative disease often accompanied with disruption of sleep-wake cycle. The sleep-wake cycle is controlled by mechanisms involving internal timekeeping (circadian) regulation. The aim of our present pilot study was to assess the circadian system in patients with mild form of AD in their home environment. In the study, 13 elderly AD patients and 13 age-matched healthy control subjects (the patient's spouses) were enrolled. Sleep was recorded for 21 days by sleep diaries in all participants and checked by actigraphy in 4 of the AD patient/control couples. The samples of saliva and buccal mucosa were collected every 4 hours during the same 24 h-interval to detect melatonin and clock gene (PER1 and BMAL1) mRNA levels, respectively. The AD patients exhibited significantly longer inactivity interval during the 24 h and significantly higher number of daytime naps than controls. Daily profiles of melatonin levels exhibited circadian rhythms in both groups. Compared with controls, decline in amplitude of the melatonin rhythm in AD patients was not significant, however, in AD patients more melatonin profiles were dampened or had atypical waveforms. The clock genes PER1 and BMAL1 were expressed rhythmically with high amplitudes in both groups and no significant differences in phases between both groups were detected. Our results suggest moderate differences in functional state of the circadian system in patients with mild form of AD compared with healthy controls which are present in conditions of their home dwelling.

Attention deficit hyperactivity disorder and disordered eating behaviors: links, risks, and challenges faced

Attention deficit hyperactivity disorder (ADHD) is a neurodevelopmental disorder that often persists in adulthood. It is defined by inattention and/or hyperactivity-impulsivity. ADHD is associated with many comorbidities, including eating disorders (EDs). In the last decade, studies have reported that ADHD is linked with binge EDs, bulimia nervosa, and anorexia nervosa. Many postulates have been proposed to explain the association: 1) impulsive behavior in ADHD patients leads to disordered eating behavior; 2) other psychologic comorbidities present in ADHD patients account for eating behavior; 3) poor eating habits and resulting nutritional deficiencies contribute to ADHD symptoms; and 4) other risk factors common to both ADHD and EDs contribute to the coincidence of both diseases. Additionally, sex differences become a significant issue in the discussion of EDs and ADHD because of the higher incidence of bulimia nervosa and anorexia nervosa in females and the ability of females to mask the symptoms of ADHD. Interestingly, both EDs and ADHD rely on a common neural substrate, namely, dopaminergic signaling. Dopaminergic signaling is critical for motor activity and emotion, the latter enabling the former into a combined motivated movement like eating. This linkage aids in explaining the many comorbidities associated with ADHD. The interconnection of ADHD and EDs is discussed from both a historical perspective and the one based on the revealing nature of its comorbidities.

Measurement in saliva from neurotypical adults of biomarkers pertinent to autism spectrum disorders

Aim:

Measure biomarkers pertinent to autism in saliva from humans.

Materials & methods:

At 7:30 PM (reading instructions) and 8:30 PM (hearing instructions), neurotypical adults (6 M, 6 F) each spat into tubes containing protease inhibitors. Cells were counted, samples aliquoted, frozen and thawed. Rationale was given for choice of biomarkers. ELISA: CD26, IL-12, carnitine, C4B, GSH, GSSG, MT-2, testosterone, IFN-γ. Mass spectrometry: cystine, glutamine, glutamic acid, GABA, serotonin. Electrochemiluminescentimmunoassay: cortisol. Radioimmunoassay: melatonin.

Results:

Cells averaged 2.16 × 10⁶/ml. M > F: CD-26, C4B, MT-2. Testosterone, cortisol. Glutamine, glutamic acid, IFN-γ, melatonin and GSSG were measurable. Remaining biomarkers were measured in <50% of samples. Concentrations were equal at both times.

Conclusion:

Saliva can be collected by literate individuals without added instruction. Ten biomarkers were measurable.

Melatonin in children with autism spectrum disorders: endogenous and pharmacokinetic profiles in relation to sleep

Supplemental melatonin has been used to treat sleep onset insomnia in children with autism spectrum disorders (ASD), although the mechanism of action is uncertain. We assessed endogenous and supplemental melatonin profiles in relation to sleep in nine children with ASD. In endogenous samples, maximal melatonin concentration (C(max)) and time to peak concentration (T(max)) were comparable to those previously published in the literature for typically developing children, and dim light melatonin onsets were captured in the majority of children. In treatment samples (supplemental melatonin), melatonin parameters were also comparable to those previously published for typically developing children. Our findings support that children with ASD and insomnia responsive to low dose melatonin treatment have relatively normal profiles of endogenous and supplemental melatonin.

The circadian system of patients with bipolar disorder differs in episodes of mania and depression

OBJECTIVES

Bipolar disorder is a common psychiatric disease characterized by mood disturbances with alternating episodes of mania and depression. Moreover, disturbances in the sleep/wake cycle are prevalent. We tested a hypothesis that the function of the circadian system, which drives the sleep/wake cycle, may differ in patients with bipolar disorder depending on whether they are experiencing an episode of mania or depression.

METHODS

To assess the functional state of the central circadian clock, daily profiles of melatonin levels in saliva were determined. The functional state of the peripheral clocks was assessed by determining daily profiles of Per1 and Nr1d1 clock gene expression in buccal mucosa cells. Sixteen patients with bipolar disorder in a manic episode, 22 patients in a depressive episode, and 19 healthy control subjects provided samples at regular intervals during a 24-hour cycle.

RESULTS

During episodes of mania, the daily profiles of melatonin differed compared with healthy controls and patients in an episode of depression, mainly due to elevated melatonin levels during the daytime. No difference was found between melatonin profiles of control subjects and patients in depression. The Per1 and Nr1d1 profiles were advanced in patients in mania compared with those in depression. Compared with controls, a trend toward an advance was apparent in the profiles of patients during an episode of mania but not depression. The amplitude of the Nr1d1 expression profile was higher in mania than in depression.

CONCLUSIONS

The data revealed differences in the functional state of the circadian system in patients with bipolar disorder depending on whether they were experiencing a manic or a depressive episode.

Melatonin and the circadian system: contributions to successful female reproduction

OBJECTIVE

To summarize the role of melatonin and circadian rhythms in determining optimal female reproductive physiology, especially at the peripheral level.

DESIGN

Databases were searched for the related English-language literature published up to March 1, 2014. Only papers in peer-reviewed journals are cited.

SETTING

Not applicable.

PATIENT(S)

Not applicable.

INTERVENTION(S)

Melatonin treatment, alterations of the normal light:dark cycle and light exposure at night.

MAIN OUTCOME MEASURE(S)

Melatonin levels in the blood and in the ovarian follicular fluid and melatonin synthesis, oxidative damage and circadian rhythm disturbances in peripheral reproductive organs.

RESULT(S)

The central circadian regulatory system is located in the suprachiasmatic nucleus (SCN). The output of this master clock is synchronized to 24 hours by the prevailing light-dark cycle. The SCN regulates rhythms in peripheral cells via the autonomic nervous system and it sends a neural message to the pineal gland where it controls the cyclic production of melatonin; after its release, the melatonin rhythm strengthens peripheral oscillators. Melatonin is also produced in the peripheral reproductive organs, including granulosa cells, the cumulus oophorus, and the oocyte. These cells, along with the blood, may contribute melatonin to the follicular fluid, which has melatonin levels higher than those in the blood. Melatonin is a powerful free radical scavenger and protects the oocyte from oxidative stress, especially at the time of ovulation. The cyclic levels of melatonin in the blood pass through the placenta and aid in the organization of the fetal SCN. In the absence of this synchronizing effect, the offspring may exhibit neurobehavioral deficits. Also, melatonin protects the developing fetus from oxidative stress. Melatonin produced in the placenta likewise may preserve the optimal function of this organ.

CONCLUSION(S)

Both stable circadian rhythms and cyclic melatonin availability are critical for optimal ovarian physiology and placental function. Because light exposure after darkness onset at night disrupts the master circadian clock and suppresses elevated nocturnal melatonin levels, light at night should be avoided.

The circadian rhythm in adult attention-deficit/hyperactivity disorder: current state of affairs

Adults with ADHD often have sleep problems that are caused by a delay of their internal circadian rhythm system. Such individuals are often typified as 'evening' or 'night' persons. This review focuses on the link between ADHD symptoms and the evening typology through multiple pathways. Etiology of the internal circadian rhythm system, the genetic basis for evening typology, overlap between ADHD symptoms and evening preference and risk factors for various chronic health conditions, including metabolic syndrome and cancer, are discussed. The treatment perspectives to reset the delayed rhythm in adults with ADHD involve psychoeducation on sleep hygiene, melatonin in the afternoon or evening and bright light therapy in the morning.

Circadian misalignment and health

Circadian rhythms are near 24-h patterns of physiology and behaviour that are present independent of external cues including hormones, body temperature, mood, and sleep propensity. The term 'circadian misalignment' describes a variety of circumstances, such as inappropriately timed sleep and wake, misalignment of sleep/wake with feeding rhythms, or misaligned central and peripheral rhythms. The predominance of early research focused on misalignment of sleep to the biological night. However, discovery of clock genes and the presence of peripheral circadian oscillators have expanded the definitions of misalignment. Experimental studies conducted in animal models and humans have provided evidence of potential mechanisms that link misalignment to negative outcomes. These include dysregulation of feeding behaviours, changes in appetite stimulating hormones, glucose metabolism and mood. This review has two foci: (1) to describe how circadian misalignment has been defined and evaluated in laboratory and field experiments, and (2) to describe evidence linking different types of circadian misalignment to increased risk for physical (cardiovascular disease, diabetes, obesity, cancer) and psychiatric (depression, bipolar, schizophrenia, attention deficit) disorders. This review will describe the role of circadian misalignment as a risk factor for disease in the general population and in clinical populations, including circadian rhythm sleep disorders and psychiatric disorders.

Adults with ADHD-without insomnia history have subclinical sleep disturbance but not circadian delay: an ADHD phenotype?

OBJECTIVE

To explore the potential ADHD phenotype of ADHD-without reported insomnia in comparison with controls and their tolerance of stimulants in a cohort rigorously screened for comorbidities.

METHOD

Adults meeting Diagnostic and Statistical Manual of Mental Disorders (4th ed., text rev.; DSM-IV-TR) criteria for ADHD-without insomnia and matched controls were administered a sleep/medication-timing questionnaire and the Pittsburgh Sleep Quality Index.

RESULTS

Among 105 participants, ADHD participants scored in the mild insomnia range and showed reduced sleep quality compared with controls, F(3, 101) = 34.9, p < .05, but no delay in bedtime/mid-sleep-time circadian measures. Sleep quality was similar between stimulant, nonstimulant, and unmedicated groups, χ(2) 2 = 0.445, p = .80. However, later timing of stimulant dosing was correlated with later sleep times, p < .01.

CONCLUSION

We isolated a potential phenotype of ADHD-without circadian delay in adults who demonstrated insomnia/sleep quality disturbance by sleep instrument, but lacked sleep-timing delay. Nevertheless, sleep delays were associated temporally with late-dosed stimulants in this group.

Body temperature, activity and melatonin profiles in adults with attention-deficit/hyperactivity disorder and delayed sleep: a case-control study

Irregular sleep-wake patterns and delayed sleep times are common in adults with attention-deficit/hyperactivity disorder, but mechanisms underlying these problems are unknown. The present case-control study examined whether circadian abnormalities underlie these sleep problems in a naturalistic home setting. We included 12 medication-naïve patients with attention-deficit/hyperactivity disorder and delayed sleep phase syndrome, and 12 matched healthy controls. We examined associations between sleep/wake rhythm in attention-deficit/hyperactivity disorder and circadian parameters (i.e. salivary melatonin concentrations, core and skin temperatures, and activity patterns) of the patients and controls during five consecutive days and nights. Daily bedtimes were more variable within patients compared with controls (F = 8.19, P < 0.001), but melatonin profiles were equally stable within individuals. Dim-light melatonin onset was about 1.5 h later in the patient group (U = 771, Z = -4.63, P < 0.001). Patients slept about 1 h less on nights before work days compared with controls (F = 11.21, P = 0.002). The interval between dim-light melatonin onset and sleep onset was on average 1 h longer in patients compared with controls (U = 1117, Z = -2.62, P = 0.009). This interval was even longer in patients with extremely late chronotype. Melatonin, activity and body temperatures were delayed to comparable degrees in patients. Overall temperatures were lower in patients than controls. Sleep-onset difficulties correlated with greater distal-proximal temperature gradient (DPG; i.e. colder hands, r(2)  = -0.32, P = 0.028) in patients. Observed day-to-day bedtime variability of individuals with attention-deficit/hyperactivity disorder and delayed sleep phase syndrome were not reflected in their melatonin profiles. Irregular sleep-wake patterns and delayed sleep in individuals with attention-deficit/hyperactivity disorder and delayed sleep phase syndrome are associated with delays and dysregulations of the core and skin temperatures.

Methylphenidate effects on blood serotonin and melatonin levels may help to synchronise biological rhythms in children with ADHD

The neuroendocrine mediators that may contribute to ADHD (Attention deficit and hyperactivity disorder), serotonin and melatonin, are both thought to regulate circadian rhythms, neurological function and stress response. The objective of this study was to determine the effect of the chronic administration of prolonged release methylphenidate (PRMPH) on daily variations in blood serotonin and melatonin and on the excretion of 6-sulphatoxy-melatonin. A total of 179 children (136 males, 42 females) between the ages of 5 and 14 (9.70 ± 2.55) years were enrolled in a controlled quasi-experimental open clinical study. Of the sample, there were 136 Children with ADHD (based on DSM-IV-TR criteria), who were further grouped into subtypes, and the 42 siblings of the participants who did not ADHD patients. Blood samples were taken at 20:00 and 09:00; urine was collected between 21:00 and 09:00. In the ADHD group, the study protocol was repeated after 4.61 ± 2.3 months of treatment. Measurements included melatonin and serotonin by RIA and urine 6-S-aMT by ELISA. Factorial analyses were conducted by STATA 12.0.

RESULTS

ADHD patients showed reduced morning serotonin with a daily profile that was different than the control group due to the predominance of nocturnal concentrations. PRMPH did not result in any significant changes. Melatonin and its daily profile did not differ between controls and the ADHD group with a diurnal rhythm showing higher morning levels that disappear after PRMPH administration. Melatonin was higher in children with predominantly hyperactive-impulsive/conduct disorder subtype. PRMPH resulted in a decrease in 6-S-aMT excretion for both ADHD subtypes.

CONCLUSION

Chronic treatment with prolonged release methylphenidate induces subtle changes in the daily fluctuations and concentrations of both serotonin and melatonin. Improvement in Children's Depression Inventory (CDI) scores was not related to a morning increase in serotonin.

Human chronotype is determined in bodily cells under real-life conditions

Individuals differ in their preferred timing of sleep and activity, which is referred to as a chronotype. The timing shows a wide distribution; extremely early chronotypes may wake up when the extremely late chronotypes fall asleep. The chronotype is supposed to be determined by the central circadian clock located in the suprachiasmatic nuclei (SCN) of the hypothalamus because the phasing of the pineal melatonin rhythm, which is driven by the SCN, correlates with the sleep timing preference. In addition to the SCN, circadian oscillators are also present in most if not all bodily cells. These peripheral clocks are synchronized by the central SCN clock and by other tissue-specific entraining cues. At the molecular level, the circadian oscillations are based on a complex, self-sustaining mechanism that drives the rhythmical expression of clock genes and their proteins. The aim of the present field study was to elucidate whether the changes in the internal timing of early and late chronotypes, as expressed by changes in the phases of their mid-sleep and melatonin secretion, can also be detected at the molecular clockwork level in subjects examined under real-life conditions. Ninety-five adult volunteers were chronotyped using an adapted Munich chronotype questionnaire to assess their mid-sleep phase, and 6 subjects with early chronotypes and 6 with late chronotypes were chosen for the study. For the assessment of the circadian phase, the subjects provided samples of saliva for the melatonin assay and samples of oral mucosa for the determination of clock gene Per1, Per2, and Rev-erbα mRNA levels every 4 h during a 24-h period. The significant correlation between the phase of the melatonin profile and timing of mid-sleep confirmed the classification of the subjects according to their chronotype. The circadian phases of the Per1, Per2, and Rev-erbα expression profiles in the oral mucosa were advanced in the early chronotypes compared with those in the late chronotypes (p < .001) and correlated significantly with the mid-sleep phase of the individual subjects. Moreover, the circadian phases of the Per1 expression profiles of individual subjects correlated significantly with the phases of their melatonin profiles (p < .05), whereas the correlation for the Per2 and Rev-erbα phases was nonsignificant, although the trend was the same. Our results demonstrate that the individual chronotype in humans living in real-life conditions affects not only the phasing of the daily melatonin rhythm in saliva but also the phasing of Per1, Per2, and Rev-erbα clock gene expression profiles in buccal mucosa cells. This report represents the first demonstration that the human peripheral circadian clock may sense the individual's chronotype under field study conditions. The data contribute to our understanding of the mechanisms underlying human chronotypes in real life.

Delayed sleep timing and symptoms in adults with attention-deficit/hyperactivity disorder: a controlled actigraphy study

Patients with attention-deficit/hyperactivity disorder (ADHD) often exhibit disrupted sleep and circadian rhythms. Determination of whether sleep disturbance and/or circadian disruption are differentially associated with symptom severity is necessary to guide development of future treatment strategies. Therefore, we measured sleep and ADHD symptoms in participants aged 19-65 who met the DSM-IV-TR (Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision) criteria for ADHD and insomnia without psychiatric comorbidities by monitoring actigraphy and daily sleep logs for 2 wks, as well as the Pittsburgh Sleep Quality Index (PSQI), Epworth Sleepiness Scale (ESS), the ADHD Rating Scale (ADHD-RS), and a clinic-designed sleep behavior questionnaire. Principal components analysis identified correlated circadian- and sleep-related variables in all participants with ADHD who completed the study (n = 24). The identified components were entered into a backwards stepwise linear regression analysis, which indicated that delayed sleep timing and increased sleepiness (ESS) (but not sleep duration or sleep efficiency) significantly predicted greater severity of both hyperactive-impulsive and inattentive ADHD symptoms (p < .05 for partial regression coefficients). In addition, combined subtypes had the most impaired age-adjusted sleep quality (PSQI scores; p < .05 compared with healthy controls; n = 13), and 91.7% of them reported going to bed late due to being "not tired/too keyed up to sleep" compared with 57.2% and 50% of inattentive and symptom-controlled participants, respectively (p < .05). In conclusion, the results of this study suggest that ADHD symptom severity correlates with delayed sleep timing and daytime sleepiness, suggesting that treatment interventions aimed at advancing circadian phase may improve daytime sleepiness. In addition, ADHD adults with combined hyperactive-impulsive and inattentive symptoms have decreased sleep quality as well as the delayed sleep timing of predominately inattentive subtypes.

Methylphenidate modifies the motion of the circadian clock

People with attention-deficit/hyperactivity disorder (ADHD) often experience sleep problems, and these are frequently exacerbated by the methylphenidate they take to manage their ADHD symptoms. Many of the changes to sleep are consistent with a change in the underlying circadian clock. The present study was designed to determine if methylphenidate alone could alter properties of the circadian clock. Young male mice were examined in light-dark cycles and in constant darkness and recordings were performed on behavioral activity, sleep, and electrical activity in the suprachiasmatic nucleus (SCN) of freely moving mice. Methylphenidate in the drinking water (0.08%) significantly increased activity in the mid-to-late night, and led to a delay in the onset of activity and sleep relative to the light-dark cycle. While locomotor levels returned to baseline after treatment ended, the phase angle of entrainment required at least a week to return to baseline levels. In constant darkness, the free-running period of both wheel-running and general locomotor rhythms was lengthened by methylphenidate. When the treatment ended, the free-running period either remained stable or only partially reverted to baseline levels. Methylphenidate also altered the electrical firing rate rhythms in the SCN. It induced a delay in the trough of the rhythm, an increment in rhythm amplitude, and a reduction in rhythm variability. These observations suggest that methylphenidate alters the underlying circadian clock. The observed changes are consistent with clock alterations that would promote sleep-onset insomnia.

Meal time shift disturbs circadian rhythmicity along with metabolic and behavioral alterations in mice

In modern society, growing numbers of people are engaged in various forms of shift works or trans-meridian travels. Such circadian misalignment is known to disturb endogenous diurnal rhythms, which may lead to harmful physiological consequences including metabolic syndrome, obesity, cancer, cardiovascular disorders, and gastric disorders as well as other physical and mental disorders. However, the precise mechanism(s) underlying these changes are yet unclear. The present work, therefore examined the effects of 6 h advance or delay of usual meal time on diurnal rhythmicities in home cage activity (HCA), body temperature (BT), blood metabolic markers, glucose homeostasis, and expression of genes that are involved in cholesterol homeostasis by feeding young adult male mice in a time-restrictive manner. Delay of meal time caused locomotive hyperactivity in a significant portion (42%) of subjects, while 6 h advance caused a torpor-like symptom during the late scotophase. Accordingly, daily rhythms of blood glucose and triglyceride were differentially affected by time-restrictive feeding regimen with concurrent metabolic alterations. Along with these physiological changes, time-restrictive feeding also influenced the circadian expression patterns of low density lipoprotein receptor (LDLR) as well as most LDLR regulatory factors. Strikingly, chronic advance of meal time induced insulin resistance, while chronic delay significantly elevated blood glucose levels. Taken together, our findings indicate that persistent shifts in usual meal time impact the diurnal rhythms of carbohydrate and lipid metabolisms in addition to HCA and BT, thereby posing critical implications for the health and diseases of shift workers.