BACKGROUND. The circadian clock is a fundamental and pervasive biological program that coordinates 24-hour rhythms in physiology, metabolism, and behavior, and it is essential to health. Whereas therapy adapted to time of day is increasingly reported to be highly successful, it needs to be personalized, since internal circadian time is different for each individual. In addition, internal time is not a stable trait, but is influenced by many factors, including genetic predisposition, age, sex, environmental light levels, and season. An easy and convenient diagnostic tool is currently missing. METHODS. To establish a validated test, we followed a 3-stage biomarker development strategy: (a) using circadian transcriptomics of blood monocytes from 12 individuals in a constant routine protocol combined with machine learning approaches, we identified biomarkers for internal time; and these biomarkers (b) were migrated to a clinically relevant gene expression profiling platform (NanoString) and (c) were externally validated using an independent study with 28 early or late chronotypes. RESULTS. We developed a highly accurate and simple assay (BodyTime) to estimate the internal circadian time in humans from a single blood sample. Our assay needs only a small set of blood-based transcript biomarkers and is as accurate as the current gold standard method, dim-light melatonin onset, at smaller monetary, time, and sample-number cost. CONCLUSION. The BodyTime assay provides a new diagnostic tool for personalization of health care according to the patient’s circadian clock. FUNDING. This study was supported by the Bundesministerium für Bildung und Forschung, Germany (FKZ: 13N13160 and 13N13162) and Intellux GmbH, Germany.

The neurodegenerative synucleinopathies, including Parkinson’s disease and dementia with Lewy bodies, are characterized by a typically lengthy prodromal period of progressive subclinical motor and non-motor manifestations. Among these, idiopathic REM sleep behaviour disorder is a powerful early predictor of eventual phenoconversion, and therefore represents a critical opportunity to intervene with neuroprotective therapy. To inform the design of randomized trials, it is essential to study the natural progression of clinical markers during the prodromal stages of disease in order to establish optimal clinical end points. In this study, we combined prospective follow-up data from 28 centres of the International REM Sleep Behavior Disorder Study Group representing 12 countries. Polysomnogram-confirmed REM sleep behaviour disorder subjects were assessed for prodromal Parkinson’s disease using the Movement Disorder Society criteria and underwent periodic structured sleep, motor, cognitive, autonomic and olfactory testing. We used linear mixed-effect modelling to estimate annual rates of clinical marker progression stratified by disease subtype, including prodromal Parkinson’s disease and prodromal dementia with Lewy bodies. In addition, we calculated sample size requirements to demonstrate slowing of progression under different anticipated treatment effects. Overall, 1160 subjects were followed over an average of 3.3 ± 2.2 years. Among clinical variables assessed continuously, motor variables tended to progress faster and required the lowest sample sizes, ranging from 151 to 560 per group (at 50% drug efficacy and 2-year follow-up). By contrast, cognitive, olfactory and autonomic variables showed modest progression with higher variability, resulting in high sample sizes. The most efficient design was a time-to-event analysis using combined milestones of motor and cognitive decline, estimating 117 per group at 50% drug efficacy and 2-year trial duration. Finally, while phenoconverters showed overall greater progression than non-converters in motor, olfactory, cognitive and certain autonomic markers, the only robust difference in progression between Parkinson’s disease and dementia with Lewy bodies phenoconverters was in cognitive testing. This large multicentre study demonstrates the evolution of motor and non-motor manifestations in prodromal synucleinopathy. These findings provide optimized clinical end points and sample size estimates to inform future neuroprotective trials.

Recent data suggest that melatonin may influence human physiology, including the sleep-wake cycle, in a time-dependent manner via the body's internal clock. Rapid-eye-movement (REM) sleep expression is strongly circadian modulated, and the impact of REM sleep on primary brain functions, metabolic processes, and immune system function has become increasingly clear over the past decade. In our study, we evaluated the effects of exogenous melatonin on disturbed REM sleep in humans. Fourteen consecutive outpatients (five women, nine men; mean age, 50 yr) with unselected neuropsychiatric sleep disorders and reduced REM sleep duration (25% or more below age norm according to diagnostic polysomnography) were included in two consecutive, randomized, double-blind, placebo-controlled, parallel design clinical trials. Patients received 3 mg melatonin daily, administered between 2200 and 2300 h for 4 wk. The results of the study show that melatonin was significantly more effective than placebo: patients on melatonin experienced significant increases in REM sleep percentage (baseline/melatonin, 14.7/17.8 vs. baseline/placebo, 14.3/12.0) and improvements in subjective measures of daytime dysfunction as well as clinical global impression score. Melatonin did not shift circadian phase or suppress temperature but did increase REM sleep continuity and promote decline in rectal temperature during sleep. These results were confirmed in patients who received melatonin in the second study (REM sleep percentage baseline/placebo/melatonin, 14.3/12.0/17.9). In patients who received melatonin in the first study and placebo in the second, the above mentioned effects outlasted the period of melatonin administration and diminished only slowly over time (REM sleep percentage baseline/melatonin/placebo, 14.7/17.8/16.2). Our findings show that exogenous melatonin, when administered at the appropriate time, seems to normalize circadian variation in human physiology. It may, therefore, have a strong impact on general health, especially in the elderly and in shift workers.

Background and Objective Daridorexant is a dual orexin receptor antagonist for the treatment of insomnia. In two phase III, 12-week studies in patients with insomnia disorder, daridorexant improved sleep and daytime functioning while maintaining a favorable safety profile. The objective of this 40-week extension study was to assess the long-term safety and tolerability of daridorexant. Methods Adults with insomnia disorder who completed the 12-week studies were invited to enroll in this double-blind extension study. Patients originally randomised to daridorexant (10 mg/25 mg/50 mg) remained on their respective treatments; patients randomised to placebo were re-randomised to daridorexant 25 mg or placebo. The 40-week treatment period was followed by a 7-day placebo run-out. The primary objective was to assess safety/tolerability. Exploratory objectives were to evaluate the efficacy of daridorexant on sleep (self-reported total sleep time) and daytime functioning (Insomnia Daytime Symptoms and Impacts Questionnaire). Results In total, 804 patients were enrolled in the study, of whom 801 received at least one dose of the study treatment and 550 patients (68.4%) completed the study. Overall incidence of treatment-emergent adverse events was similar across groups (35–40%). Daridorexant did not induce next-morning sleepiness and no withdrawal-related symptoms or rebound were observed after treatment discontinuation. Improvements in sleep and daytime functioning were maintained through to the end of the study and were most pronounced with daridorexant 50 mg. Daridorexant 50 mg, compared with placebo, increased self-reported total sleep time by a least-squares mean of 20.4 (95% confidence interval [CI] 4.2, 36.5), 15.8 (95% CI − 0.8, 32.5) and 17.8 (95% CI − 0.4, 35.9) minutes and decreased (i.e., improved) Insomnia Daytime Symptoms and Impacts Questionnaire total scores by a least-squares mean of − 9.3 (95% CI − 15.1, − 3.6), − 9.5 (95% CI − 15.4, − 3.5) and − 9.1 (95% CI − 15.6, − 2.7), at weeks 12, 24 and 36 of the extension study, respectively. Conclusions Treatment with daridorexant, for up to 12 months, was generally safe and well tolerated. Exploratory efficacy analyses suggest that the sustained improvements in sleep and daytime functioning with daridorexant 50 mg support its use for long-term treatment of insomnia disorder, without concerns of new safety signals. Clinical Trial Registration ClinicalTrials.gov (NCT03679884) [first posted: 21 September, 2018], https://clinicaltrials.gov/ct2/show/NCT03679884.

Life in 24-h society relies on the use of artificial light at night that might disrupt synchronization of the endogenous circadian timing system to the solar day. This could have a negative impact on sleep–wake patterns and psychiatric symptoms. The aim of the study was to investigate the influence of evening light emitted by domestic and work place lamps in a naturalistic setting on melatonin levels and alertness in humans. Healthy subjects (6 male, 3 female, 22–33 years) were exposed to constant dim light (<10 lx) for six evenings from 7:00 p.m. to midnight. On evenings 2 through 6, 1 h before habitual bedtime, they were also exposed to light emitted by 5 different conventional lamps for 30 min. Exposure to yellow light did not alter the increase of melatonin in saliva compared to dim light baseline during (38 ± 27 pg/mL vs. 39 ± 23 pg/mL) and after light exposure (39 ± 22 pg/mL vs. 44 ± 26 pg/mL). In contrast, lighting conditions including blue components reduced melatonin increase significantly both during (office daylight white: 25 ± 16 pg/mL, bathroom daylight white: 24 ± 10 pg/mL, Planon warm white: 26 ± 14 pg/mL, hall daylight white: 22 ± 14 pg/mL) and after light exposure (office daylight white: 25 ± 15 pg/mL, bathroom daylight white: 23 ± 9 pg/mL, Planon warm white: 24 ± 13 pg/mL, hall daylight white: 22 ± 26 pg/mL). Subjective alertness was significantly increased after exposure to three of the lighting conditions which included blue spectral components in their spectra. Evening exposure to conventional lamps in an everyday setting influences melatonin excretion and alertness perception within 30 min.