EEG alpha peak frequency: cognitive impairment severity marker in isolated REM sleep behavior disorder.

Isolated REM sleep behavior disorder (iRBD) is a prodrome of α-synucleinopathies like Parkinson's disease (PD) and dementia with Lewy bodies (DLB). The best marker for prediction of lead time to phenoconversion is reduced striatal dopamine transporter (DaT)-binding, unavailable for most patients. This study investigated EEG alpha peak frequency (APF) slowing - an established marker of cognitive deterioration - as a severity marker in iRBD patients.

Living in Biological Darkness II: Impact of Winter Habitual Daytime Light on Night-Time Sleep.

Timing and architecture of sleep are co-driven by circadian rhythms modulated by their major Zeitgeber light and darkness. In a natural environment, one is exposed to 3.000 lx (cloudy winter sky) to 100.

Relating Photoperiod and Outdoor Temperature With Sleep Architecture in Patients With Neuropsychiatric Sleep Disorders.

While artificial light in urban environments was previously thought to override seasonality in humans, recent studies have challenged this assumption. We aimed to explore the relationship between seasonally varying environmental factors and changes in sleep architecture in patients with neuropsychiatric sleep disorders by comparing two consecutive years. In 770 patients, three-night polysomnography was performed at the Clinic for Sleep & Chronomedicine (St.

Seasonality of human sleep: Polysomnographic data of a neuropsychiatric sleep clinic.

While short-term effects of artificial light on human sleep are increasingly being studied, reports on long-term effects induced by season are scarce. Assessments of subjective sleep length over the year suggest a substantially longer sleep period during winter. Our retrospective study aimed to investigate seasonal variation in objective sleep measures in a cohort of patients living in an urban environment.

Prognostic biomarkers in prodromal α-synucleinopathies: DAT binding and REM sleep without atonia.

Background: Isolated rapid eye movement (REM) sleep behaviour disorder (iRBD) is a prodromal state of clinical α-synucleinopathies such as Parkinson's disease and Lewy body dementia. The lead-time until conversion is unknown. The most reliable marker of progression is reduced striatal dopamine transporter (DAT) binding, but low availability of imaging facilities limits general use.

Inter-layer and inter-subject variability of diurnal gene expression in human skin.

The skin is the largest human organ with a circadian clock that regulates its function. Although circadian rhythms in specific functions are known, rhythms in the proximal clock output, gene expression, in human skin have not been thoroughly explored. This work reports 24 h gene expression rhythms in two skin layers, epidermis and dermis, in a cohort of young, healthy adults, who maintained natural, regular sleep-wake schedules.

Post-Illumination Pupil Response as a Biomarker for Cognition in α-Synucleinopathies.

Neurodegenerative processes in the brain are reflected by structural retinal changes. As a possible biomarker of cognitive state in prodromal α-synucleinopathies, we compared melanopsin-mediated post-illumination pupil response (PIPR) with cognition (CERAD-plus) in 69 patients with isolated REM-sleep behavior disorder. PIPR was significantly correlated with cognitive domains, especially executive functioning (r = 0.

Living in Biological Darkness: Objective Sleepiness and the Pupillary Light Responses Are Affected by Different Metameric Lighting Conditions during Daytime.

Nighttime melatonin suppression is the most commonly used method to indirectly quantify acute nonvisual light effects. Since light is the principal zeitgeber in humans, there is a need to assess its strength during daytime as well. This is especially important since humans evolved under natural daylight but now often spend their time indoors under artificial light, resulting in a different quality and quantity of light.

The alerting effect of the wake maintenance zone during 40 hours of sleep deprivation.

Under entrained conditions, the accumulation of homeostatic sleep pressure in the evening is opposed by a strong circadian arousal signal prior to the dim light melatonin onset, called the Wake Maintenance Zone (WMZ). This study aimed at investigating the impact of the WMZ on different cognitive performance tests, as well as on subjective and objective sleepiness. Twelve young male participants completed a constant routine protocol with 40 h of extended wakefulness that included two WMZs.

High-accuracy determination of internal circadian time from a single blood sample.

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.

Blue-Enriched Morning Light as a Countermeasure to Light at the Wrong Time: Effects on Cognition, Sleepiness, Sleep, and Circadian Phase.

Light during the day and darkness at night are crucial factors for proper entrainment of the human circadian system to the solar 24-h day. However, modern life and work styles have led to much more time spent indoors, often with lower daytime and higher evening/nighttime light intensity from electrical lighting than outdoors. Whether this has long-term consequences for human health is being currently investigated.

Applying Melanopic Lux to Measure Biological Light Effects on Melatonin Suppression and Subjective Sleepiness.

Objective: At the beginning of this century, a novel photopigment, melanopsin, was discovered in a sub-class of retinal ganglion cells and its action spectrum was described. Shortly after, it became evident that melanopsin is a major contributor to non-visual eye-mediated effects of light on e.g.