scholarly journals Afraid of the dark: Light acutely suppresses activity in the human amygdala

PLoS ONE ◽  
2021 ◽  
Vol 16 (6) ◽  
pp. e0252350
Author(s):  
Elise M. McGlashan ◽  
Govinda R. Poudel ◽  
Sharna D. Jamadar ◽  
Andrew J. K. Phillips ◽  
Sean W. Cain
Keyword(s):  
Light Exposure ◽  
Negative Emotion ◽  
Critical Role ◽  
Dark Light ◽  
Direct Light ◽  
Siemens Scanner ◽  
Amygdala Activity ◽  
Plausible Mechanism ◽  
Dim Light ◽  
Effect Of Light

Light improves mood. The amygdala plays a critical role in regulating emotion, including fear-related responses. In rodents the amygdala receives direct light input from the retina, and light may play a role in fear-related learning. A direct effect of light on the amygdala represents a plausible mechanism of action for light’s mood-elevating effects in humans. However, the effect of light on activity in the amygdala in humans is not well understood. We examined the effect of passive dim-to-moderate white light exposure on activation of the amygdala in healthy young adults using the BOLD fMRI response (3T Siemens scanner; n = 23). Participants were exposed to alternating 30s blocks of light (10 lux or 100 lux) and dark (<1 lux), with each light intensity being presented separately. Light, compared with dark, suppressed activity in the amygdala. Moderate light exposure resulted in greater suppression of amygdala activity than dim light. Furthermore, functional connectivity between the amygdala and ventro-medial prefrontal cortex was enhanced during light relative to dark. These effects may contribute to light’s mood-elevating effects, via a reduction in negative, fear-related affect and enhanced processing of negative emotion.

scholarly journals The Effect of Light Exposure on Water Sorption and Solubility of Self-Adhesive Resin Cements

2014 ◽  
Vol 2014 ◽  
pp. 1-6 ◽  
Author(s):  
Thaiane Rodrigues Aguiar ◽  
Carolina Bosso André ◽  
Gláucia Maria Boni Ambrosano ◽  
Marcelo Giannini
Keyword(s):  
Water Sorption ◽  
Mechanical Stability ◽  
Light Exposure ◽  
Water Immersion ◽  
Constant Mass ◽  
Resin Cements ◽  
Adhesive Resin ◽  
Direct Light ◽  
Immersion Period ◽  
Effect Of Light

Purpose. To investigate the effect of light activation on the water sorption (WS) and solubility (SL) of resin cements after 24 h and 7 days. Methods. Disk-shaped specimens were prepared using five dual-polymerized cements (four self-adhesive [RelyX Unicem, MaxCem, SeT and G-Cem] and one conventional [Panavia F 2.0]) and divided according to the curing mode (direct light exposure or self-cure) and water immersion period (24 h or 7 days). Specimens were dry-stored and weighed daily until a constant mass was recorded (M1). Then, specimens were stored in water for either 24 h or 7 days and immediately weighed (M2). After desiccation, specimens were weighed again until a constant mass was achieved (M3). WS and SL were calculated and statistically analyzed by Kruskal-Wallis, Dunn and Mann-Whitney U tests (α=0.05%). Results. There was a significant increase in WS for all products after one-week immersion in water. The highest water uptake was observed for autopolymerized groups. Extended water immersion significantly affected the SL for most of autopolymerized cements. Significant differences between products were observed in both tests. Conclusions. The curing mode and the water immersion period may affect the mechanical stability of the resin cements, and these differences appear to be product-dependent.

Sensor-Based Estimation of Dim Light Melatonin Onset Using Features of Two Time Scales

2021 ◽  
Vol 2 (3) ◽  
pp. 1-15
Author(s):  
Cheng Wan ◽  
Andrew W. Mchill ◽  
Elizabeth B. Klerman ◽  
Akane Sano
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Light Exposure ◽  
Biological Activities ◽  
Second Step ◽  
Sampled Data ◽  
Dim Light Melatonin Onset ◽  
Dim Light ◽  
Using Data ◽  
Mean Square Errors

Circadian rhythms influence multiple essential biological activities, including sleep, performance, and mood. The dim light melatonin onset (DLMO) is the gold standard for measuring human circadian phase (i.e., timing). The collection of DLMO is expensive and time consuming since multiple saliva or blood samples are required overnight in special conditions, and the samples must then be assayed for melatonin. Recently, several computational approaches have been designed for estimating DLMO. These methods collect daily sampled data (e.g., sleep onset/offset times) or frequently sampled data (e.g., light exposure/skin temperature/physical activity collected every minute) to train learning models for estimating DLMO. One limitation of these studies is that they only leverage one time-scale data. We propose a two-step framework for estimating DLMO using data from both time scales. The first step summarizes data from before the current day, whereas the second step combines this summary with frequently sampled data of the current day. We evaluate three moving average models that input sleep timing data as the first step and use recurrent neural network models as the second step. The results using data from 207 undergraduates show that our two-step model with two time-scale features has statistically significantly lower root-mean-square errors than models that use either daily sampled data or frequently sampled data.

scholarly journals 111 Artificial Light-Triggered Sleep Deprivation May Lead to Allodynia in Rodent Model

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A45-A46
Author(s):  
Skyler Kanegi ◽  
Armen Akopian
Keyword(s):  
Sleep Deprivation ◽  
Light Exposure ◽  
Light Stimulus ◽  
Continuous Light ◽  
Artificial Light ◽  
Light Cycle ◽  
Tissue Samples ◽  
Mechanical Threshold ◽  
Dim Light ◽  
Von Frey Filaments

Abstract Introduction The combination of artificial light and lack of exposure to natural light can delay the circadian clock, dysregulate the circadian cycle, and decrease alertness upon waking. This effect has been especially significant during the COVID-19 pandemic, where overexposure to artificial light at improper hours has contributed to increased rates of clinical insomnia. Artificial light may also contribute to concomitant neurological conditions such as primary headache, but the mechanisms by which light triggers sleep deprivation-induced headache are not well-understood. Methods To measure pain sensitivity, we habituated 13 wild-type male mice to von Frey filaments applied to the periorbital area until there was no response to 0.6g stimulus. We then applied 5 lux of continuous dim light to mice during their usual 12-hour dark cycle. The 12-hour light cycle remained unchanged with 200 lux continuous light. Three groups of mice experienced the dim light stimulus for one, three, or five consecutive days. Ambulation and rest activity were measured using SOF-812 Activity Monitor machines. After the experiment concluded, we waited 24 hours and measured mechanical threshold using von Frey filaments at 1, 3, 5, 8, and every 3 days subsequently until mice no longer responded to 0.6g stimulus. Results Artificial light triggered changes in circadian behavior including increased number of rest periods during 12-hour dark (dim light) cycle and shortened sleep duration during 12-hour light cycle. Following the artificial light stimulus, there was a significant decrease in mechanical threshold (P&lt;0.05), representing allodynia. The one-day group displayed one day of significant allodynia. The three-day group displayed three days of significant allodynia. The five-day group displayed five days of significant allodynia. Conclusion Artificial light may trigger circadian dysregulation, and the duration of artificial light exposure seemed to be directly correlated to the duration of allodynia up to one week after the stimulus was removed. We will repeat these experiments and analyze CNS and PNS tissue samples to understand the underlying physiological and biochemical bases of how artificial light triggers sleep deprivation-induced headache. This knowledge could increase our understanding of the pathophysiology and comorbidity of sleep deprivation and headache. Support (if any) Funding was received from the National Institute of Health (NS104200).

Dry eye following cataract surgery: The effect of light exposure using an in-vitro model

2018 ◽  
Vol 41 (1) ◽  
pp. 128-131 ◽  
Author(s):  
Tugce Ipek ◽  
Mariana Petronela Hanga ◽  
Andreas Hartwig ◽  
James Wolffsohn ◽  
Clare O’Donnell
Keyword(s):  
Cataract Surgery ◽  
Dry Eye ◽  
In Vitro Model ◽  
Light Exposure ◽  
Vitro Model ◽  
Effect Of Light

INTERACTIONS OF THE PINEAL AND EXPOSURE TO CONTINUOUS LIGHT ON ORGAN WEIGHTS OF FEMALE RATS

1961 ◽  
Vol 36 (4) ◽  
pp. 617-624 ◽  
Author(s):  
Richard Jay Wurtman ◽  
Willard Roth ◽  
Mark D. Altschule ◽  
Judith J. Wurtman
Keyword(s):  
Light Exposure ◽  
Continuous Light ◽  
Female Rats ◽  
Constant Light ◽  
Ovarian Weight ◽  
Organ Weights ◽  
Bovine Pineal Extracts ◽  
Pineal Extracts ◽  
Effect Of Light

ABSTRACT Either exposure to constant light for 80 days or pinealectomy produced similar changes in the weights of the ovaries and adrenals of female rats. These were not additive when both procedures were employed. Pinealectomy did not share with light-exposure the capacity to induce uterine hypertrophy. Rats exposed to constant light for 56 days had lighter pineals than animals kept in darkness; this decrease was not affected by administration of bovine pineal extracts. The increase in ovarian weight produced in rats by exposure to light for 56 days was prevented by bovine pineal extracts, but these extracts were without effect on the uterine hypertrophy produced under the same conditions. These data suggest that the effect of light upon the weight of the ovary is mediated via the pineal.

Letter to the Editor

PEDIATRICS ◽  
1969 ◽  
Vol 44 (3) ◽  
pp. 456-457
Author(s):  
Thomas H. Milby
Keyword(s):  
Seasonal Variations ◽  
Light Exposure ◽  
Letter To The Editor ◽  
Two Populations ◽  
Effect Of Light

Dr. Aase's question about the possibility that differences in exposure to light might have accounted for our observed differences in bilirubin levels is, of course, germane. During the course of our study, we became aware of the reports which described the effect of light on degradation of bilirubin. However, we could determine no differences in light exposure between the two populations under study nor, because of the physical arrangements of the nurseries, did there appear to be any possibility that there would be seasonal variations in the amount of light exposure.

Salivary Secretion under the Influence of Bright/Dim Light Exposure in the Morning and Evening in Humans

2002 ◽  
Vol 33 (2) ◽  
pp. 129-140 ◽  
Author(s):  
Ki Ja Hyun ◽  
Hiromi Tokura ◽  
Koichi Gotoh ◽  
Masayuki Kondo ◽  
Takako Akimoto ◽  
...  
Keyword(s):  
Light Exposure ◽  
Salivary Secretion ◽  
Dim Light

scholarly journals The Influence of Light Exposure in Ambiance during Pregnancy in Maternal and Fetal Outcomes: An Experimental Study

2018 ◽  
Vol 41 (01) ◽  
pp. 024-030
Author(s):  
Vitor Sarri ◽  
Beatriz Ferrari ◽  
Larissa Magalhães ◽  
Paula Rodrigues ◽  
Almir Rezende ◽  
...  
Keyword(s):  
Light Exposure ◽  
Good Practice ◽  
Histological Evaluation ◽  
Reproductive Parameters ◽  
Anthropometric Measures ◽  
Dark Light ◽  
Mean Values ◽  
Lighting Conditions ◽  
Significant Difference ◽  
Environmental Lighting

Objective The aim of this study is to evaluate whether exposure to different environmental lighting conditions affects the reproductive parameters of pregnant mice and the development of their offspring. Methods Fifteen pregnant albino mice were divided into three groups: light/dark, light, and dark. The animals were euthanized on day 18 of pregnancy following the Brazilian Good Practice Guide for Euthanasia of Animals. Maternal and fetal specimens were measured and collected for histological evaluation. Analysis of variance (ANOVA) test was used for comparison of the groups considering p ≤ 0.05 to be statistically significant. Results There was no significant difference in the maternal variables between the three groups. Regarding fetal variables, significant differences were observed in the anthropometric measures between the groups exposed to different environmental lighting conditions, with the highest mean values in the light group. The histological evaluation showed the same structural pattern of the placenta in all groups, which was within the normal range. However, evaluation of the uterus revealed a discrete to moderate number of endometrial glands in the light/dark and light groups, which were poorly developed in most animals. In the fetuses, pulmonary analysis revealed morphological features consistent with the transition from the canalicular to the saccular phase in all groups. Conclusion Exposure to different environmental lighting conditions had no influence on the reproductive parameters of female mice, while the offspring of mothers exposed to light for 24 hours exhibited better morphometric features.

scholarly journals Outside the Eye of the Storm: Can Moderate Hurricane Exposure Improve Social, Psychological, and Attachment Functioning?

2019 ◽  
Author(s):  
Anthony D Mancini ◽  
Maren Westphal ◽  
Paul Griffin
Keyword(s):  
Social Support ◽  
Negative Emotion ◽  
Critical Role ◽  
Hurricane Sandy ◽  
Attachment Anxiety ◽  
Moderate Intensity ◽  
Social Psychological ◽  
Attachment Avoidance ◽  
Matched Comparison ◽  
Global Distress

High-intensity disaster can harm psychological functioning. Could moderate-intensity disaster improve psychological and attachment functioning through its effects on social functioning? We used a prospective quasi-experimental cohort design to investigate this possibility among college students. Hurricane cohort participants (N = 209) completed assessments before, two weeks, and six weeks after Hurricane Sandy. Two matched comparison cohorts (Ns &gt; 140) were assessed four months and one year later. The hurricane cohort, in contrast to matched comparison cohorts, reported increased social support, reduced global distress, reduced negative emotion, and reduced attachment avoidance at the end of the semester. Increased social support mediated the relationship between hurricane cohort and reduced global distress, negative emotion, attachment avoidance, and attachment anxiety, and increased positive emotion and self-esteem at six weeks post-storm. The results suggest moderate disaster exposure can benefit short-term social, psychological, and attachment functioning, underscoring the critical role of the social context in stress adaptation.

Treatment of Seasonal Affective Disorder with Light in the Evening

1985 ◽  
Vol 147 (4) ◽  
pp. 424-428 ◽  
Author(s):  
Steven P. James ◽  
Thomas A. Wehr ◽  
David A. Sack ◽  
Barbara L. Parry ◽  
Norman E. Rosenthal
Keyword(s):  
Sleep Deprivation ◽  
Affective Disorder ◽  
Seasonal Affective Disorder ◽  
Bright Light ◽  
Early Morning ◽  
Antidepressant Effect ◽  
Comparison Study ◽  
Female Patients ◽  
Dim Light ◽  
Effect Of Light

A cross-over comparison study of exposure, in the evenings only, to bright versus dim light was carried out on nine female patients with seasonal affective disorder. A significant antidepressant effect of the bright lights was shown. No consistent observable effects were produced by the dim lights. These results support earlier studies demonstrating the efficacy of bright light given morning and evening. The antidepressant effect of light is not mediated by sleep deprivation, and the early morning hours are not crucial for a response.

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