The purpose of the study was to study the associations of tobacco, alcohol, marijuana, and coffee use and insomnia complaints (IC) in adolescents with special consideration of the influence of coffee consumption on these relationships. 7698 Subjects aged 11-17 years were investigated in a cross-sectional study within the German Health Interview and Examination Survey for Children and Adolescents. Self-report questionnaires were distributed to the participants. Hierarchical regression analyses were performed to assess possible effects of coffee consumption on the association of tobacco, alcohol, and marijuana use with IC. Common risk factors for insomnia were included in the adjusted analyses. Tobacco, alcohol, marijuana and coffee use displayed significant bivariate associations with IC. After adjusting the first three substances for coffee consumption, their associations with IC were reduced considerably. After additionally adjusting for other potential confounders (age, gender, socio-economic status, externalizing and internalizing psychiatric problems, media use, bodyweight, medical condition), frequent coffee consumption, high alcohol intake and frequent smoking contributed to the prediction of IC in male subjects while frequent coffee consumption and high alcohol intake predicted the occurrence of IC in females. Coffee consumption could be an important risk factor for IC in adolescents and it significantly affects the association of smoking, alcohol, and marijuana with IC. Future research that includes long-term studies about psychoactive substance use (PSU) and sleep should also consider coffee consumption. Parents, educators, clinicians, and researchers should be aware of the potentially hazardous influence of PSU, especially coffee, alcohol and tobacco, on sleep in young individuals.

A more recent branch of research describes the importance of sleep problems in the development and treatment of mental disorders in children and adolescents, such as attention-deficit hyperactivity disorder (ADHD) and mood disorders (MD). Research about clock genes has continued since 2012 with a focus on metabolic processes within all parts of the mammalian body, but particularly within different cerebral regions. Research has focused on complex regulatory circuits involving clock genes themselves and their influence on circadian rhythms of diverse body functions. Current publications on basic research in human and animal models indicate directions for the treatment of mental disorders targeting circadian rhythms and mechanisms. The most significant lines of research are described in this paper.

This study investigated the interaction between motorcortical excitability (short interval cortical inhibition, intracortical facilitation and long interval cortical inhibition), different requirement conditions [choice reaction test (CRT), attention/go/nogo], and their pharmacological modulation by methylphenidate (MPH) in normal healthy adults (n = 31) using a transcranial magnetic stimulation paradigm. MPH was administered in a dosage of 1 mg/kg body weight, maximum 60 mg. Additionally, serum level and clearance of MPH were controlled. The statistical analysis of variance revealed a significant three-way interaction of 2 (MPH) x 3 (CRT) x 6 (ISI) predicting motor evoked potential amplitudes (P = 0.032, MPH none and full dose, n = 31). In order to compare effects of dosage an additional between-subjects factor (half vs. full MPH dose) was introduced. None of the interactions involving this between-subject factor reached statistical significance. Exploring interactions with MPH only, a 3 (MPH none, half and full dose) x 3 (CRT) x 6 (ISI) analysis of variance revealed significant two-way interactions for MPH x ISI (P = 0.040) and condition x ISI (P < 0.001, n = 18). Effects observed for MPH were strongest on facilitatory processes, weaker for intracortical inhibition. In sum, MPH seems to interact via striato-thalamo-cortical pathways with original motorcortical processes (ISI), to a lesser extent with task-dependent or behavioral parameters (CRT).

CLOCK gene research and the analysis of circadian rhythmicity on the behavioural, cellular and molecular level are increasingly contributing to accumulate clinically relevant knowledge in the fields of neuroscience, psychopharmacology and adult psychiatry. However, the role of circadian phenomena, including sleep alterations in mental disorders during childhood and adolescence remains largely enigmatic. Fortunately, recent publications have addressed this problem and there is now some evidence available highlighting the relevance of CLOCK genes in conditions, such as ADHD, mood disorders, schizophrenia and anxiety disorders.

Introduction: Sleep, circadian rhythms, (mental) health, and development are assumed to be intertwined. However, differentiated and reliable parameters of sleep and circadian rhythms are particularly difficult to assess for Fragile X (FXS) individuals. As those parameters need to be observed in complex settings, the feasibility of measurements for people with FXS was to be proven. Findings from this pilot study can inform further research and help to estimate sample sizes for future studies on FXS patients. Methods and Sample: Nine individuals (male and female) with full mutation of the FMR1 gene were integrated in the study and underwent a complex measurement including actigraphy, sleep log, and 24-h saliva sampling in order to examine profiles of melatonin and cortisol, and a polysomnography. Results: Seven actigraphy profiles, eight sleep logs, eight saliva profiles and seven polysomnographic data sets were collected. Complete data were analyzed for six individuals [mean age 14.87 years (SD 4.12), mean BMI 25.90 (SD 4.44)] were collected. No drop outs due to the constraints of the assessment were registered. Discussion: All assessments and the setting in total were tolerated well by participants and caregivers. Procedures were adapted to individual needs of the participants. Conclusion: All its components and the setting in total are absolutely feasible in the specific population of FXS individuals. Losses during consenting and recruiting have to be planned as well as high amounts of interindividual variances have to be taken into account.