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Light at night

Jenny Q Ouyang, Scott Davies, Davide Dominoni
Alternation between day and night is a predictable environmental fluctuation that organisms use to time their activities. Since the invention of artificial lighting, this predictability has been disrupted and continues to change in a unidirectional fashion with increasing urbanization. As hormones mediate individual responses to changing environments, endocrine systems might be one of the first systems affected, as well as being the first line of defense to ameliorate any negative health impacts. In this Review, we first highlight how light can influence endocrine function in vertebrates...
March 15, 2018: Journal of Experimental Biology
Aurore Quinault, Corinne Leloup, Geoffrey Denwood, Coralie Spiegelhalter, Marianne Rodriguez, Philippe Lefebvre, Nadia Messaddeq, Quan Zhang, Catherine Dacquet, Luc Pénicaud, Stephan C Collins
The rhythmic nature of insulin secretion over the 24h cycle in pancreatic islets has been mostly investigated using transcriptomics studies showing that modulation of insulin secretion over this cycle is achieved via distal stages of insulin secretion. We set out to measure β-cell exocytosis using in depth cell physiology techniques at several time points. In agreement with the activity and feeding pattern of nocturnal rodents, we find that C57/Bl6J islets in culture for 24h exhibit higher insulin secretion during the corresponding dark phase than in the light phase (Zeitgeber Time ZT20 and ZT8, respectively, in vivo)...
2018: PloS One
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
M G Carta, A Preti, H S Akiskal
Human population is increasing in immense cities with millions of inhabitants, in which life is expected to run 24 hours a day for seven days a week (24/7). Noise and light pollution are the most reported consequences, with a profound impact on sleep patterns and circadian biorhythms. Disruption of sleep and biorhythms has severe consequences on many metabolic pathways. Suppression of melatonin incretion at night and the subsequent effect on DNA methylation may increase the risk of prostate and breast cancer...
2018: Clinical Practice and Epidemiology in Mental Health: CP & EMH
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
Ha Kyun Kim, Hyun Jung Kim, Jae Hyung Kim, Tae Hoon Kim, Sang Hag Lee
Numerous peripheral tissues possess self-sustaining daily biologic rhythms that are regulated at the molecular level by clock genes such as PER1, PER2, CLOCK, and BMAL1. Physiological function of nasal mucosa exhibits rhythmic variability to a day-night environmental cycle. Nevertheless, little is known of the expression and distribution pattern of clock genes in nasal mucosa. The present study investigates the expression level and distribution pattern of PER1, PER2, CLOCK, and BMAL1 genes in nasal mucosa of healthy controls, allergic rhinitis patients, and normal rats...
2018: PloS One
Maria Eugenia Correa-Cano, Bárbara Goettsch, James P Duffy, Jonathan Bennie, Richard Inger, Kevin J Gaston
Naturally dark nighttime environments are being widely eroded by the introduction of artificial light at night (ALAN). The biological impacts vary with the intensity and spectrum of ALAN, but have been documented from molecules to ecosystems. How globally severe these impacts are likely to be depends in large part on the relationship between the spatio-temporal distribution of ALAN and that of the geographic ranges of species. Here, we determine this relationship for the Cactaceae family. Using maps of the geographic ranges of cacti and nighttime stable light composite images for the period 1992 to 2012, we found that a high percentage of cactus species were experiencing ALAN within their ranges in 1992, and that this percentage had increased by 2012...
March 12, 2018: Scientific Reports
William D S Killgore, Haley C Kent, Sara A Knight, Anna Alkozei
Humans demonstrate a circadian rhythm of melatonin production that closely tracks the daily light/dark cycle, with profound increases in circulating levels during the night-time and nearly nonexistent levels during daylight hours. Although melatonin is known to play a role in preparing the brain and body for sleep, its effects on cognition and brain function are not well understood. We hypothesized that declines in morning melatonin would be associated with increased functional activation within cortical regions involved in alertness, attention, and executive function...
March 9, 2018: Neuroreport
Vasily Mikhaïlovitch Smirnov, Christina Zeitz, Nagasamy Soumittra, Isabelle Audo, Sabine Defoort-Dhellemmes
INTRODUCTION: CABP4-related retinal dysfunction is a cone-rod synaptic transmission disorder with electronegative electroretinogram (ERG) waveform. It is a rare retinal dysfunction that can be classified into the incomplete form of congenital stationary night blindness. Absent foveal reflex and overall foveal thinning were previously reported, but in most cases the fundus appearance was described as nearly normal. We report here peculiar macular changes in a patient of French ancestry harbouring CABP4 mutations...
March 10, 2018: Documenta Ophthalmologica. Advances in Ophthalmology
Shenhai Gong, Tian Lan, Liyan Zeng, Haihua Luo, Xiaoyu Yang, Na Li, Xiaojiao Chen, Zhanguo Liu, Rui Li, Sanda Win, Shuwen Liu, Hongwei Zhou, Bernd Schnabl, Yong Jiang, Neil Kaplowitz, Peng Chen
BACKGROUND & AIMS: Acetaminophen (APAP) induced hepatotoxicity is a leading cause of acute liver failure worldwide. It is well established that the liver damage induced by acetaminophen exhibits diurnal variation. However, the detailed mechanism for the hepatotoxic variation is not clear. Here we aimed to determine the relative contributions of gut microbiota in modulating the diurnal variation of hepatotoxicity induced by APAP. METHODS: Male Balb/C mice were treated with or without antibiotics and orally administrated a single dose of APAP (300 mg/kg) at ZT0 (when the light is on-start of resting period) and ZT12 (when the light is off-start of active period)...
March 7, 2018: Journal of Hepatology
Kaitryn E Ronning, Gabriel Peinado Allina, Eric B Miller, Robert J Zawadzki, Edward N Pugh, Rolf Hermann, Marie E Burns
Rods and cones mediate visual perception over 9 log units of light intensities, with both photoreceptor types contributing to a middle 3-log unit range that comprises most night-time conditions. Rod function in this mesopic range has been difficult to isolate and study in vivo because of the paucity of mutants that abolish cone signaling without causing photoreceptor degeneration. Here we describe a novel Gnat2 knockout mouse line (Gnat2-/- ) ideal for dissecting rod and cone function. In this line, loss of Gnat2 expression abolished cone phototransduction, yet there was no loss of cones, disruption of the photoreceptor mosaic, nor change in general retinal morphology up to at least 9 months of age...
March 5, 2018: Experimental Eye Research
Malgorzata Zalesinska
A proper visual performance by drivers can be ensured by, among else, a correct distribution of luminance in their field of view. At night, when the driver's sight is adapted to low luminance levels, high luminance level objects located near the road may be a source of glare, which is not only a nuisance, but it may also blind the driver. For many years, LED billboards (light-emitting diode billboards) have been installed near roads. Such billboards are usually large, have high luminance and show dynamically changing images...
February 28, 2018: Accident; Analysis and Prevention
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
Nazir S Hawi, Maya Samaha, Mark D Griffiths
Background and aims The latest (fifth) edition of the Diagnostic and Statistical Manual of Mental Disorders included Internet gaming disorder (IGD) as a disorder that needs further research among different general populations. In line with this recommendation, the primary objective of this was to explore the relationships between IGD, sleep habits, and academic achievement in Lebanese adolescents. Methods Lebanese high-school students (N = 524, 47.9% males) participated in a paper survey that included the Internet Gaming Disorder Test and demographic information...
February 28, 2018: Journal of Behavioral Addictions
Jutta S Mayer, Katharina Hees, Juliane Medda, Oliver Grimm, Philip Asherson, Mariano Bellina, Michael Colla, Pol Ibáñez, Elena Koch, Antonio Martinez-Nicolas, Adrià Muntaner-Mas, Anna Rommel, Nanda Rommelse, Saskia de Ruiter, Ulrich W Ebner-Priemer, Meinhard Kieser, Francisco B Ortega, Johannes Thome, Jan K Buitelaar, Jonna Kuntsi, J Antoni Ramos-Quiroga, Andreas Reif, Christine M Freitag
BACKGROUND: The risk for major depression and obesity is increased in adolescents and adults with attention-deficit / hyperactivity disorder (ADHD) and adolescent ADHD predicts adult depression and obesity. Non-pharmacological interventions to treat and prevent these co-morbidities are urgently needed. Bright light therapy (BLT) improves day-night rhythm and is an emerging therapy for major depression. Exercise intervention (EI) reduces obesity and improves depressive symptoms. To date, no randomized controlled trial (RCT) has been performed to establish feasibility and efficacy of these interventions targeting the prevention of co-morbid depression and obesity in ADHD...
February 26, 2018: Trials
Kimberley F Prior, Daan R van der Veen, Aidan J O'Donnell, Katherine Cumnock, David Schneider, Arnab Pain, Amit Subudhi, Abhinay Ramaprasad, Samuel S C Rund, Nicholas J Savill, Sarah E Reece
Circadian rhythms enable organisms to synchronise the processes underpinning survival and reproduction to anticipate daily changes in the external environment. Recent work shows that daily (circadian) rhythms also enable parasites to maximise fitness in the context of ecological interactions with their hosts. Because parasite rhythms matter for their fitness, understanding how they are regulated could lead to innovative ways to reduce the severity and spread of diseases. Here, we examine how host circadian rhythms influence rhythms in the asexual replication of malaria parasites...
February 26, 2018: PLoS Pathogens
Thomas Raap, Rianne Pinxten, Marcel Eens
Artificial light at night (ALAN) is a widespread and increasing environmental pollutant with known negative impacts on animal physiology and development. Physiological effects could occur through sleep disruption and deprivation, but this is difficult to quantify, especially in small developing birds. Sleep loss can potentially be quantified by using oxalate, a biomarker for sleep debt in adult humans and rats. We examined the effect of ALAN on oxalate in free-living developing great tits ( Parus major ) as effects during early-life could have long-lasting and irreversible consequences...
2018: Conservation Physiology
Hiroki Yoshioka, Tsunemasa Nonogaki, Yasuro Shinohara, Masumi Suzui, Yurie Mori, Gi-Wook Hwang, Katsumi Ohtani, Nobuhiko Miura
The aim of the present study is to investigate the "chronotoxicity" of seven metal compounds (Hg, Pb, Ni, Cr, Cu, Zn, or Fe) by assessing how their toxicity varies with circadian periodicity. Male ICR mice were injected with each metal compound intraperitoneally at 6 different time points over the course of a day (zeitgeber time [ZT]: ZT2, ZT6, ZT10, ZT14, ZT18 and ZT22). Mortality was then monitored until 14 days after the injection. Our investigation demonstrated that mice were tolerant against Ni toxicity during dark phase, on the other hand, they were tolerant against Cr toxicity during light phase...
2018: Journal of Toxicological Sciences
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
Sergio A Cabrera-Cruz, Jaclyn A Smolinsky, Jeffrey J Buler
Excessive or misdirected artificial light at night (ALAN) produces light pollution that influences several aspects of the biology and ecology of birds, including disruption of circadian rhythms and disorientation during flight. Many migrating birds traverse large expanses of land twice every year at night when ALAN illuminates the sky. Considering the extensive and increasing encroachment of light pollution around the world, we evaluated the association of the annual mean ALAN intensity over land within the geographic ranges of 298 nocturnally migrating bird species with five factors: phase of annual cycle, mean distance between breeding and non-breeding ranges, range size, global hemisphere of range, and IUCN category of conservation concern...
February 19, 2018: Scientific Reports
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