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Dim light

Minqi Yang, Ning Ma, Yingying Zhu, Ying-Chu Su, Qingwei Chen, Fan-Chi Hsiao, Yanran Ji, Chien-Ming Yang, Guofu Zhou
Exposure to bright light is typically intermittent in our daily life. However, the acute effects of intermittent light on alertness and sleep have seldom been explored. To investigate this issue, we employed within-subject design and compared the effects of three light conditions: intermittent bright light (30-min pulse of blue-enriched bright light (~1000 lux, ~6000 K) alternating with 30-min dim normal light (~5 lux, ~3600 K) three times); continuous bright light; and continuous dim light on subjective and objective alertness and subsequent sleep structure...
March 15, 2018: International Journal of Environmental Research and Public Health
Michael Cleary-Gaffney, Andrew N Coogan
Circadian rhythms are recurring patterns in a range of behavioural, physiological and molecular parameters that display periods of near 24 h, and are underpinned by an endogenous biological timekeeping system. Circadian clocks are increasingly recognised as being key for health. Environmental light is the key stimulus that synchronises the internal circadian system with the external time cues. There are emergent health concerns regarding increasing worldwide prevalence of electric lighting, especially man-made light-at-night, and light's impact on the circadian system may be central to these effects...
March 11, 2018: Physiology & Behavior
Enrique Barragán-Garza, Douglas D Koch, Luis G Vargas, Alan Lang, Adam Roy
PURPOSE: To assess the clinically acceptable range of inlay decentration with respect to the light-constricted pupil center and the coaxially sighted corneal light reflex (CSCLR) for an inlay (Raindrop Near Vision Inlay; ReVision Optics, Inc., Lake Forest, CA) that reshapes the anterior corneal surface. METHODS: In this retrospective, observational cohort study of 115 patients with emmetropic or low hyperopic presbyopia who were implanted with a shape-changing corneal inlay, visual acuity, task performance (in good and dim light), reports of halos and glare, and satisfaction data were collected from the preoperative and 3-month postoperative examinations...
March 1, 2018: Journal of Refractive Surgery
Peter M DiGeronimo, Simone R R Pisano, Nicola Di Girolamo, Carl F Spielvogel, Gordon J Pirie, Rene Carter
Indian flying foxes ( Pteropus giganteus) are adapted to visual foraging in dim light. Nine Indian flying foxes were taken from a captive colony of 25 animals and placed in quarantine, off exhibit, in preparation for shipment to another institution. The exhibit had indirect, natural sunlight and was large enough to allow for flight. The quarantine enclosure was subject to >12 hr/day artificial lighting and did not allow for flight or gliding. Diet was identical between groups. After 13 mo, ophthalmic examination was performed on each animal including evaluation of the anterior chamber, rebound tonometry in upright and hanging positions, measurement of palpebral fissure length, and vertical and horizontal corneal diameters...
March 2018: Journal of Zoo and Wildlife Medicine: Official Publication of the American Association of Zoo Veterinarians
Stephanie J Crowley, Charmane I Eastman
Sleep timing shifts later during adolescence (second decade). This trend reverses at ~20 years and continues to shift earlier into adulthood. The current analysis examined the hypothesis that a longer free-running circadian period during late adolescence (14-17 years) compared with adulthood (30-45 years) accounts for sleep timing differences. Sex and ancestry were also examined because previous reports find that women and those with African-American ancestry have shorter free-running periods. Circadian period was measured using an ultradian dark-light protocol (2 hr dark/sleep, 2 hr dim room light [~20 lux]/wake) over 3...
March 8, 2018: Journal of Sleep Research
Philip Cheng, Gabriel Tallent, Helen J Burgess, Kieulinh Michelle Tran, Thomas Roth, Christopher L Drake
STUDY OBJECTIVES: Recent evidence indicates that daytime sleep disturbance associated with night shift work may arise from both circadian misalignment and sleep reactivity to stress. This presents an important clinical challenge because there are limited means of predicting and distinguishing between the two mechanisms, and the respective treatments differ categorically; however, there is support that a polymorphism in the PERIOD3 gene ( PER3 ) may indicate differences in vulnerability to daytime sleep disturbance in shift workers...
February 27, 2018: Journal of Clinical Sleep Medicine: JCSM: Official Publication of the American Academy of Sleep Medicine
Lameese D Akacem, Kenneth P Wright, Monique K LeBourgeois
Although the light-induced melatonin suppression response is well characterized in adults, studies examining the dynamics of this effect in children are scarce. The purpose of this study was to quantify the magnitude of evening light-induced melatonin suppression in preschool-age children. Healthy children (n = 10; 7 females; 4.3 ± 1.1 years) participated in a 7-day protocol. On days 1-5, children followed a strict sleep schedule. On day 6, children entered a dim light environment (<15 lux) for 1-h before providing salivary samples every 20- to 30-min from the afternoon until 50-min after scheduled bedtime...
March 2018: Physiological Reports
Catarina C V Oliveira, Filipe Figueiredo, Florbela Soares, Wilson Pinto, Maria Teresa Dinis
The present study reveals the first characterization of the plasma melatonin rhythms of the meagre (Argyrosomus regius) under aquaculture conditions. Melatonin levels were monitored during a 24 h cycle under a photoperiod of 16 L:8D and under constant darkness (DD), respectively to characterize the daily rhythm of this indoleamine and to test its endogenous origin. Besides, to identify which light intensities are perceived as night or day by this species, the degree of inhibition of nocturnal melatonin production caused by increasing intensities of light was tested (3...
March 2, 2018: Fish Physiology and Biochemistry
Adriana D Cruz, Maria Cn Castro, Marcelo F Aguiar, Ludmilla S Guimarães, Cinthya C Gomes
OBJECTIVES: To assess the radiographic appearances of the endodontic treatment in different room lighting conditions and image display devices. METHODS: After approval by Research Ethical Board, 20 images were obtained from blocks with one endodontically treated tooth. The 20 endodontic treatments were made in the laboratory, of those randomly selected, 10 teeth (50% of sample) received some quality defect in three parameters as apical limit, adaptation to root canal and homogeneity of the root canal filling material...
March 1, 2018: Dento Maxillo Facial Radiology
Solenne Van der Maren, Christophe Moderie, Catherine Duclos, Jean Paquet, Véronique Daneault, Marie Dumont
A number of factors can contribute to a delayed sleep schedule. An important factor could be a daily profile of light exposure favoring a later circadian phase. This study aimed to compare light exposure between 14 young adults complaining of a delayed sleep schedule and 14 matched controls and to identify possible associations between habitual light exposure and circadian phase. Exposure to white and blue light was recorded with ambulatory monitors for 7 consecutive days. Participants also noted their daily use of light-emitting devices before bedtime...
February 1, 2018: Journal of Biological Rhythms
Daniel G McHail, Nazanin Valibeigi, Theodore C Dumas
The neural bases of cognition may be greatly informed by relating temporally defined developmental changes in behavior with concurrent alterations in neural function. A robust improvement in performance in spatial learning and memory tasks occurs at 3 wk of age in rodents. We reported that the developmental increase of spontaneous alternation in a Y-maze was related to changes in temporal dynamics of fast glutamatergic synaptic transmission in the hippocampus. We also showed that, during allothetic behaviors in the Y-maze, network oscillation power increased at frequency bands known to support spatial learning and memory in adults...
March 2018: Learning & Memory
Romesh G Abeysuriya, Steven W Lockley, Peter A Robinson, Svetlana Postnova
A biophysical model of the key aspects of melatonin synthesis and excretion has been developed, which is able to predict experimental dynamics of melatonin in plasma and saliva, and of its urinary metabolite 6-sulfatoxymelatonin (aMT6s). This new model is coupled to an established model of arousal dynamics, which predicts sleep and circadian dynamics based on light exposure and times of wakefulness. The combined model thus predicts melatonin levels over the sleep-wake/dark-light cycle and enables prediction of melatonin-based circadian phase markers, such as dim light melatonin onset (DLMO) and aMT6s acrophase under conditions of normal sleep and circadian misalignment...
February 13, 2018: Journal of Pineal Research
Ala Morshedian, Michael L Woodruff, Gordon L Fain
Recoverin is a small molecular-weight, calcium-binding protein in rod outer segments which binds to G-protein receptor kinase 1 (GRK1) and can alter the rate of rhodopsin phosphorylation. A change in phosphorylation should change the lifetime of light-activated rhodopsin and the gain of phototransduction, but deletion of recoverin has little effect on the sensitivity of rods either in the dark or in dim-to-moderate background light. We describe two additional functions perhaps of greater physiological significance...
February 12, 2018: Journal of Physiology
Prashant Kumar, Jing Liu, Pranay Ranjan, Yaowu Hu, Sharma Srkc Yamijala, Swapan K Pati, Joseph Irudayaraj, Gary J Cheng
Even though transition metal dichalcogenides (TMDCs) are deemed to be novel photonic and optoelectronic 2D materials, the visible band gap being often limited to monolayer, hampers their potential in niche applications due to fabrication challenges. Uncontrollable defects and degraded functionalities at elevated temperature and under extreme environments further restrict their prospects. To address such limitations, the discovery of a new 2D material, α-PbO is reported. Micromechanical as well as sonochemical exfoliation of 2D atomic sheets of α-PbO are demonstrated and its optical behavior is investigated...
February 12, 2018: Small
Chihak Lee, Youngsu Oh, In Seon Yoon, Sun Hong Kim, Byeong-Kwon Ju, Jae-Min Hong
Electrochromic devices (ECDs) are emerging as a novel technology for various applications like commercialized smart window glasses, and auto-dimming rear-view mirrors. Recently, the development of low-power, lightweight, flexible, and stretchable devices has been accelerated to meet the growing demand in the new wearable devices market. Silver nanowires (AgNWs) can become new primary transparent conducting electrode (TCE) materials to replace indium tin oxide (ITO) for ECDs. However, issues such as substrate adhesion, delamination, and higher resistance still exist with AgNWs...
February 9, 2018: Scientific Reports
Fan Yang, Hongwei Ma, Xi-Qin Ding
Thyroid hormone (TH) is essential in numerous physiological functions and developmental processes. It acts through TH receptors (TRs) to regulate gene expression. The retina is the light-sensitive tissue lining the back of the eye and functions as the first step of the visual process. Rod and cone photoreceptors are specialized sensory neurons in the retina that initiate phototransduction. Rods are responsible for dim light vision, whereas cones are responsible for daytime vision, color vision, and visual acuity...
2018: Vitamins and Hormones
Luca Sorrentino, Alessandra Sartani, Gaia Pietropaolo, Daniela Bossi, Serena Mazzucchelli, Marta Truffi, Diego Foschi, Fabio Corsi
BACKGROUND: The equipment to detect indocyanine green (ICG) fluorescence for sentinel lymph node (SLN) biopsy in breast cancer is not widely accessible nor optimal. The fluorescence appears as a poorly defined white shine on a black background, and dimmed lighting is required. The aim of this study was to assess the feasibility, accuracy and healthcare costs of a novel approach for SLN biopsy by a video-assisted ICG-guided technique. METHODS: The technique for detecting SLN was radioisotope (RI) in 194 cases, video-assisted ICG-guided in 70 cases and a combined method in 71 cases...
February 5, 2018: World Journal of Surgery
Leslie A Salas-Estrada, Nicholas Leioatts, Tod D Romo, Alan Grossfield
Rhodopsin, a prototypical G protein-coupled receptor, is a membrane protein that can sense dim light. This highly effective photoreceptor is known to be sensitive to the composition of its lipidic environment, but the molecular mechanisms underlying this fine-tuned modulation of the receptor's function and structural stability are not fully understood. There are two competing hypotheses to explain how this occurs: 1) lipid modulation occurs via solvent-like interactions, where lipid composition controls membrane properties like hydrophobic thickness, which in turn modulate the protein's conformational equilibrium; or 2) protein-lipid interactions are ligand-like, with specific hot spots and long-lived binding events...
January 23, 2018: Biophysical Journal
Vilayanur S Ramachandran, Chaipat Chunharas, Rachel Croft, Nader Batal
We report some new observations on what could be regarded as the world's simplest visual illusion-the autokinetic effect. When a single dim spot of light is viewed in a completely dark room, it moves vividly in random directions. During steady fixation, perhaps subtle eye movements cause the image to move and a failure to correct for this using eye movement command signals leads to motion perception. This is especially true because eye muscle fatigue can lead to miscalibration. However, if two dots are shown, they often move independently in different directions, which negate the eye movement theory...
January 2018: I-Perception
Michael R Dolsen, James K Wyatt, Allison G Harvey
Sleep and circadian rhythm changes during adolescence contribute to increased risk across emotional, behavioral, cognitive, social, and physical health domains. This study examines if sleep and dim light melatonin onset (DLMO) are related to greater risk in these 5 health domains. Participants were 163 (93 female, age = 14.7 years) adolescents with an evening circadian preference from a study funded by the Eunice Kennedy Shriver National Institute of Child Health and Human Development. Sleep and circadian measures included weekday total sleep time (TST), bedtime, and shut-eye time assessed via sleep diary, the Children's Morningness-Eveningness Preferences scale, and DLMO...
January 25, 2018: Journal of Clinical Child and Adolescent Psychology
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