Phase angle circadian

STUDY OBJECTIVES: Altered light sensitivity may be an underlying vulnerability for disrupted circadian photoentrainment. The photic information necessary for circadian photoentrainment is sent to the circadian clock from melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs). The current study tested whether the responsivity of ipRGCs measured using the post-illumination pupil response (PIPR) was associated with circadian phase, sleep timing, and circadian alignment, and if these relationships varied by season or depression severity...

Elite athletes are vulnerable to sleep and circadian disruption and associated mental health symptoms. This study aimed to investigate sex differences in sleep, circadian rhythms, and mental health, as well as the moderating role of sex in the prediction of mental health, among male professional and female semi-professional elite athletes. Participants were 87 elite Australian Rules football (ARF) athletes (43% female; mean [standard deviation] age 24.0 [4.1] years). Participants completed baseline questionnaires, 2 weeks of sleep/wake monitoring via actigraphy, and a circadian phase assessment (dim-light melatonin onset [DLMO])...

Surely most chronobiologists believe circadian clocks are an adaptation of organisms that enhances fitness, but are we certain that this focus of our research effort really confers a fitness advantage? What is the evidence, and how do we evaluate it? What are the best criteria? These questions are the topic of this review. In addition, we will discuss selective pressures that might have led to the historical evolution of circadian systems while considering the intriguing question of whether the ongoing climate change is modulating these selective pressures so that the clock is still evolving...

OBJECTIVE: To determine whether there is a correlation between mood and the alignment between the timing of the circadian pacemaker (circadian phase) and the timing of sleep in healthy, euthymic individuals. METHODS: Participants were 25 first-year medical students (25.9 ± 3.3years, 16 females). Mood (Profile of Mood States, brief form) and circadian phase (salivary dim light melatonin onset) were assessed 4 times over 7weeks. Circadian alignment was determined using the dim light melatonin onset to average midsleep interval (phase angle difference)...

The circadian clock times physiological and behavioural processes and resets on a daily basis to synchronize with the environment. The involvement of the circadian clock in photoperiodic time measurement synchronising annual rhythms is still under debate and different models have been proposed explaining their integration. Insects overcome unfavourable conditions in diapause, a form of dormancy. A latitudinal cline in diapause induction in the parasitoid wasp Nasonia vitripennis as well as a difference in circadian light sensitivity between north and south provide us with additional evidence that the circadian system of Nasonia is involved in photoperiodic time measurement and that latitude-specific seasonality drives adaptive evolution in photoperiodism partly through adaptation responses in the circadian system...

Circadian rhythm disruption is a core symptom of bipolar disorder (BD), also reflected in altered patterns of melatonin release. Reductions of grey matter (GM) volumes are well documented in BD. We hypothesized that levels and timing of melatonin secretion in bipolar depression could be associated with depressive psychopathology and brain GM integrity. The onset of melatonin secretion under dim light conditions (DLMO) and the amount of time between DLMO and midsleep (i.e. phase angle difference; PAD) were used as circadian rhythm markers...

OBJECTIVES: Dim light melatonin onset, or the rise in melatonin levels representing the beginning of the biological night, is the gold standard indicator of circadian phase. Considerably less is known about dim light melatonin offset, or the decrease in melatonin to low daytime levels representing the end of the biological night. In the context of insufficient sleep, morning circadian misalignment, or energy intake after waketime but before dim light melatonin offset, is linked to impaired insulin sensitivity, suggesting the need to characterize dim light melatonin offset and identify risk for morning circadian misalignment...

OBJECTIVE: The alignment between environmental stimuli (e.g., dark, light) and behavior cycles (e.g., rest, activity) is an essential feature of the circadian timing system, a key contributor to metabolic health. However, no previous studies have investigated light-activity alignment in relation to glycemic control in human populations. RESEARCH DESIGN AND METHODS: The analysis included ∼7,000 adults (aged 20-80 years) from the National Health and Nutrition Examination Survey (NHANES) (2011-2014) with actigraphy-measured, multiday, 24-h activity and light data...

The main aim of this study was to explore how melatonin onset timing and phase angle to bedtime in healthy older adults are impacted by prior light exposure. A total of 13 healthy older (ages 56-74) individuals were studied on two successive evenings. Prior to the first evening, the participants were in self-selected lighting conditions for the first 4-6 h of the day and then were in dim light (3 lux) until their scheduled bedtime. On the second day, individuals from Project A remained in the dim lighting conditions throughout the entire day but those in Project B were in more typical indoor lighting (~90 lux) throughout the day...

Primary cilia, dynamic microtubule-based organelles, play crucial roles in cellular homeostasis, development, and signal transduction. Despite the recognition of their importance, the complex dynamics of cilia, particularly their potential roles in the brain, circadian rhythms, and neurological processes, remain largely unexplored. Here, we conduct a comprehensive exploration of the spatiotemporal variability and circadian rhythms of primary cilia length and orientation across 22 distinct mouse brain regions by analyzing over 10 million individual cilia...

OBJECTIVE: To evaluate the effects of a single bimatoprost implant administration on 24-hour intraocular pressure (IOP) lowering at 8 weeks, and 1-year IOP-lowering efficacy and safety outcomes. DESIGN: Multicenter, open-label, 12-month phase 3b study (NCT04285580). PARTICIPANTS: Adults with open-angle glaucoma or ocular hypertension. METHODS: Participants (n=31) received 10-μg bimatoprost implant in the study eye on day 1...

Due to time zones, sun time and local time rarely match. The difference between local and sun time, which we designate by Solar Jet Lag (SoJL), depends on location within a time zone and can range from zero to several hours. Daylight Saving Time (DST) simply adds one hour to SoJL, independent of location. We hypothesized that the impact of DST, is particularly problematic in patients with Delayed Sleep-Wake Phase Disorder (DSWPD), worsening their sleep debt. DSWPD is characterized by a chronic misalignment between the internal and social timing, reflected by an inability to fall asleep and wakeup at conventional or socially acceptable times...

Preclinical quantitative models of cognitive performance are necessary for translation from basic research to clinical studies. In rodents, non-cognitive factors are a potential influence on testing outcome and high variability in behavior requires multiple time point testing for better assessment of performance in more sophisticated tests. Thus, these models have limited translational value as most human cognitive tests characterize cognition using single digit scales to distinguish between impaired and unimpaired function...

Circadian rhythms alter with ageing and may be aetiologically linked to neurodegeneration. This study explored the association between clinical markers and 1) dim light melatonin onset (DLMO) time and 2) phase angle derived from sleep midpoint, in older adults with varying dementia risks. Participants completed 14 days of actigraphy followed by in-lab measurement of salivary melatonin, from which DLMO time and phase angle were computed. Eighty participants (age = 65.5, SD = 9.6), 44 males (55%), MMSE (28...

The increasing number of people living with HIV (PLWH) have an elevated incidence of risk for non-communicable comorbidities, the aetiology of which remains incompletely understood. Whilst sleep disturbances are often reported in PLWH, it is unknown to what extent they relate to changes in the circadian and/or sleep homeostatic processes. We studied the relationship between sleep characteristics, circadian phase, and HIV status in older adults from the HAALSI subsample of the Agincourt Health and Demographic Surveillance System in South Africa (n=187, 36 HIV+, age: 66...

Decision-making has been shown to suffer when circadian preference is misaligned with time of assessment; however, little is known about how misalignment between sleep timing and the central circadian clock impacts decision-making. This study captured naturally occurring variation in circadian alignment (i.e., alignment of sleep-wake timing with the central circadian clock) to examine if greater misalignment predicts worse decision-making. Over the course of 2 weeks, 32 late adolescent drinkers (aged 18-22 years; 61% female; 69% White) continuously wore actigraphs and completed two overnight in-laboratory visits (Thursday and Sunday) in which both dim-light melatonin onset (DLMO) and behavioural decision-making (risk taking, framing, and strategic reasoning tasks) were assessed...

Circadian rhythm disorder is a significant risk factor for mental diseases, and the recovery of circadian rhythm function has gradually become a signal of effective antidepressant therapy. Sini Powder (SNP) is a classical, traditional Chinese formula for depression treatment. However, few clinical reports have been recorded. This randomized, double-blinded, controlled trial (ChiCTR1900022700) aimed to explore the efficacy of SNP on depression via regulating circadian rhythm. In total, 36 patients with major depressive disorder (MDD) were enrolled for 4-weeks medication and 6-weeks follow-up...

Growing epidemiological evidence points towards an association between fragmented 24-h rest-activity cycles and cognition in the aged. Alterations in the circadian timing system might at least partially account for these observations. Here, we tested whether daytime rest is associated with changes in concomitant 24-h rest probability profiles, circadian timing and neurobehavioural outcomes in healthy older adults. Sixty-three individuals (59 - 82 years) underwent field actigraphy monitoring, in-lab dim light melatonin onset (DLMOn) assessment and an extensive cognitive test battery...

BACKGROUND: Circadian dysregulation has long been thought to be a key component in the pathophysiology of bipolar disorder (BD). However, it remains unclear whether this dysregulation constitutes a risk factor, manifestation, or consequence of BD. This study aimed to compare dim light melatonin secretion patterns between unaffected offspring of parents with BD (OBD) and offspring of control parents (OCP). METHODS: This case-control study included unaffected OBD (mean age 14...

BACKGROUND: This study is a confirmatory efficacy trial of two treatments for winter seasonal affective disorder (SAD): SAD-tailored group cognitive-behavioral therapy (CBT-SAD) and light therapy (LT). In our previous efficacy trial, post-treatment outcomes for CBT-SAD and LT were very similar, but CBT-SAD was associated with fewer depression recurrences two winters later than LT (27.3% in CBT-SAD vs. 45.6% in LT). CBT-SAD engaged and altered a specific mechanism of action, seasonal beliefs, which mediated CBT-SAD's acute antidepressant effects and CBT-SAD's enduring benefit over LT...