Sleep insufficiency and bedtime irregularity in children with ADHD: A population-based analysis.

Background: Sleep is impaired in children with attention-deficit/hyperactivity disorder (ADHD). However, population-based examination of indicators of sleep insufficiency and bedtime irregularity is limited. This investigation examined associations between ADHD, weeknight sleep insufficiency, and bedtime irregularity in a nationally-representative child sample, and indicators of these sleep outcomes in ADHD.

Human-Centric Lighting Research and Policy in the Melanopsin Age.

Beyond visual function, specialized light-sensitive retinal circuits involving the photopigment melanopsin drive critical aspects of human physiology and behavior, including sleep-wake rhythms, hormone production, mood, and cognition. Fundamental discoveries of visual neurobiology dating back to the 1990s have given rise to strong interest from the lighting industry in optimizing lighting to benefit health. Consequently, evidence-based recommendations, regulations, and policies need to translate current knowledge of neurobiology into practice.

Optimizing Light Flash Sequence Duration to Shift Human Circadian Phase.

Unlike light input for forming images, non-image-forming retinal pathways are optimized to convey information about the total light environment, integrating this information over time and space. In a variety of species, discontinuous light sequences (flashes) can be effective stimuli, notably impacting circadian entrainment. In this study, we examined the extent to which this temporal integration can occur.

Electric lighting, adolescent sleep and circadian outcomes, and recommendations for improving light health.

Light is a potent circadian entraining agent. For many people, daily light exposure is fundamentally dysregulated with reduced light during the day and increased light into the late evening. This lighting schedule promotes chronic disruption to circadian physiology resulting in a myriad of impairments.

Impact of daytime spectral tuning on cognitive function.

Light at night can improve alertness and cognition. Exposure to daytime light, however, has yielded less conclusive results. In addition to direct effects, daytime light may also mitigate the impact of nocturnal light exposure on alertness.

Duration invariance and intensity dependence of the human circadian system phase shifting response to brief light flashes.

The melanopsin-containing intrinsically photosensitive retinal ganglion cells (ipRGCs) are characterized by a delayed off-time following the cessation of light stimulation. Here, we exploited this unusual physiologic property to characterize the exquisite sensitivity of the human circadian system to flashed light. In a 34 h in-laboratory between-subjects design, we examined phase shifting in response to variable-intensity (3-9500 photopic lux) flashes at fixed duration (2 ms; = 28 participants) and variable-duration (10 µs-10 s) flashes at fixed intensity (2000 photopic lux; = 31 participants).

Plasticity in perception: insights from color vision deficiencies.

Inherited color vision deficiencies typically result from a loss or alteration of the visual photopigments absorbing light and thus impact the very first step of seeing. There is growing interest in how subsequent steps in the visual pathway might be calibrated to compensate for the altered receptor signals, with the possibility that color coding and color percepts might be less severely impacted than the receptor differences predict. These compensatory adjustments provide important insights into general questions about sensory plasticity and the sensory and cognitive processes underlying how we experience color.

Color perception and compensation in color deficiencies assessed with hue scaling.

Anomalous trichromats have three classes of cone receptors but with smaller separation in the spectral sensitivities of their longer-wave (L or M) cones compared to normal trichromats. As a result, the differences in the responses of the longer-wave cones are smaller, resulting in a weaker input to opponent mechanisms that compare the LvsM responses. Despite this, previous studies have found that their color percepts are more similar to normal trichromats than the smaller LvsM differences predict, suggesting that post-receptoral processes might amplify their responses to compensate for the weaker opponent inputs.

Effect of Suvorexant vs Placebo on Total Daytime Sleep Hours in Shift Workers: A Randomized Clinical Trial.

Importance: Many shift workers have difficulty sleeping during the daytime owing to an inappropriately timed circadian drive for wakefulness.

Objective: To determine whether a dual hypocretin receptor antagonist would enable shift workers to have more daytime sleep.

Design, Setting, And Participants: This double-blind, placebo-controlled randomized clinical trial included 2 weeks of baseline data and 3 weeks of intervention data, from March 2016 to December 2018.

The accuracy of artificial and natural light measurements by actigraphs.

Actigraphs are the reference standard for measuring light exposure in human non-laboratory experiments due to their portability and long battery lives. However, actigraphs typically have a limited illuminance operating range not representative of real-world conditions, and for many actigraphs, the accuracy of their light measurement has not been verified independently. We assessed the illuminances recorded by Activinsights GENEActiv Original and Philips Actiwatch 2 actigraphs in comparison to a calibrated, laboratory-standard photometer, under both artificial light-emitting diode (LED) and natural sunlight illuminations that might be encountered by a person under real-world conditions.

Auditory psychomotor vigilance testing in older and young adults: a revised threshold setting procedure.

Background: One of the most common ways to examine the daytime impact of sleep loss is the use of the psychomotor vigilance test (PVT). PVT metrics, including median reaction time (RT) and number of lapses, have been examined in a variety of studies in which both acute and chronic sleep times are manipulated. Most of these studies involve young, healthy individuals and use a visual stimulus.

Melanopsin-mediated pupil function is impaired in Parkinson's disease.

Parkinson's disease (PD) is characterised by non-motor symptoms including sleep and circadian disruption. Melanopsin-expressing intrinsically photosensitive Retinal Ganglion Cells (ipRGC) transmit light signals to brain areas controlling circadian rhythms and the pupil light reflex. To determine if non-motor symptoms observed in PD are linked to ipRGC dysfunction, we evaluated melanopsin and rod/cone contributions to the pupil response in medicated participants with PD (n = 17) and controls (n = 12).

A feasibility study of 2-mm bolus for postmastectomy radiation therapy.

Purpose: The purpose of this study was to prospectively evaluate the use of daily 2-mm bolus in patients undergoing postmastectomy radiation without reconstruction using optically stimulated luminescence dosimetry and weekly assessment of skin toxicity.

Methods And Materials: We prospectively collected data from the first 49 women treated with a daily 2-mm Superflab bolus during their postmastectomy radiation therapy from 2013 to 2016 at The University of Chicago Comprehensive Cancer Center at Silver Cross. Within the first 3 days of starting radiation therapy, we measured the surface dose in vivo at 5 anatomical locations under the 2-mm bolus on the chest wall.

The Effects of Short-Term Light Adaptation on the Human Post-Illumination Pupil Response.

Purpose: We determine the effect of short-term light adaptation on the pupil light reflex and the melanopsin mediated post-illumination pupil response (PIPR). Inner and outer retinal photoreceptor contributions to the dark-adapted pupil response were estimated.

Methods: In Experiment A, light adaptation was studied using short wavelength lights ranging from subthreshold to suprathreshold irradiances for melanopsin signaling that were presented before (5-60 seconds) and after (30 seconds) a melanopsin-exciting stimulus pulse.

Melanopsin-mediated post-illumination pupil response in the peripheral retina.

Intrinsically photosensitive retinal ganglion cells (ipRGCs) regulate pupil size by integrating extrinsic rod and cone signals with intrinsic melanopsin-mediated phototransduction. Light adapted pupil diameter is determined by the corneal flux density (CFD), and for central visual field stimulation the melanopsin-mediated post-illumination pupil response (PIPR) follows this same CFD relationship. Rods, cones, and ipRGCs vary in size, density, and distribution across the retina, but how these differences affect the amplitude and timing of the extrinsic and intrinsic pupil light reflex in the central and peripheral retina is unknown.

Temporal characteristics of melanopsin inputs to the human pupil light reflex.

Rods, cones and melanopsin containing intrinsically photosensitive retinal ganglion cells (ipRGCs) operate in concert to regulate pupil diameter. The temporal properties of intrinsic ipRGC signalling are distinct to those of rods and cones, including longer latencies and sustained signalling after light offset. We examined whether the melanopsin mediated post-illumination pupil response (PIPR) and pupil constriction were dependent upon the inter-stimulus interval (ISI) between successive light pulses and the temporal frequency of sinusoidal light stimuli.

Effect of rod-cone interactions on mesopic visual performance mediated by chromatic and luminance pathways.

We studied the effect of rod-cone interactions on mesopic visual reaction time (RT). Rod and cone photoreceptor excitations were independently controlled using a four-primary photostimulator. It was observed that (1) lateral rod-cone interactions increase the cone-mediated RTs; (2) the rod-cone interactions are strongest when rod sensitivity is maximal in a dark surround, but weaker with increased rod activity in a light surround; and (3) the presence of a dark surround nonselectively increased the mean and variability of chromatic (+L-M, S-cone) and luminance (L+M+S) RTs independent of the level of rod activity.