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Dim light

Dirk Jan Stenvers, Rick van Dorp, Ewout Foppen, Jorge Mendoza, Anne-Loes Opperhuizen, Eric Fliers, Peter H Bisschop, Johanna H Meijer, Andries Kalsbeek, Tom Deboer
Exposure to light at night (LAN) is associated with insomnia in humans. Light provides the main input to the master clock in the hypothalamic suprachiasmatic nucleus (SCN) that coordinates the sleep-wake cycle. We aimed to develop a rodent model for the effects of LAN on sleep. Therefore, we exposed male Wistar rats to either a 12 h light (150-200lux):12 h dark (LD) schedule or a 12 h light (150-200 lux):12 h dim white light (5 lux) (LDim) schedule. LDim acutely decreased the amplitude of daily rhythms of REM and NREM sleep, with a further decrease over the following days...
October 20, 2016: Scientific Reports
Marc A Bouffard, Wayne T Cornblath, Joseph F Rizzo, Michael S Lee, Lindsey B DeLott, Eric R Eggenberger, Nurhan Torun
BACKGROUND: Transient monocular vision loss (TMVL) is an alarming symptom owing to potentially serious etiologies such as thromboembolism or giant cell arteritis. Our objective is to describe the phenomenon of TMVL present on awakening, which may represent a distinct and benign entity. METHODS: We performed a retrospective observational case series of 29 patients who experienced TMVL on awakening. Patients who described monocular dimming or blackout of vision were included, and those with blurred vision, concurrent eye pain, and binocular vision loss were excluded...
September 29, 2016: Journal of Neuro-ophthalmology: the Official Journal of the North American Neuro-Ophthalmology Society
Annette van Maanen, Anne Marie Meijer, Marcel G Smits, Kristiaan B van der Heijden, Frans J Oort
STUDY OBJECTIVES: Chronic sleep onset insomnia with late melatonin onset is prevalent in childhood, and has negative daytime consequences. Melatonin treatment is known to be effective in treating these sleep problems. Bright light therapy might be an alternative treatment, with potential advantages over melatonin treatment. In this study, we compare the effects of melatonin and bright light treatment with a placebo condition in children with chronic sleep onset insomnia and late melatonin onset...
October 10, 2016: Sleep
Sandrine Bujaldon, Natsumi Kodama, Fabrice Rappaport, Rajagopal Subramanyam, Catherine de Vitry, Yuichiro Takahashi, Francis-André Wollman
The green alga Chlamydomonas reinhardtii contains several light-harvesting chlorophyll a/b complexes (LHC); four major LHCIIs, two minor LHCIIs and nine LHCIs. We characterized three chlorophyll b-less mutants to assess the effect of chlorophyll b deficiency on the function, assembly and stability of these chlorophyll a/b-binding proteins. We identified point mutations in two mutants that inactivate the CAO gene responsible for chlorophyll a to chlorophyll b conversion. All LHCIIs accumulated to wild type levels in a CAO mutant but their light-harvesting function for photosystem-II was impaired...
October 11, 2016: Molecular Plant
Enmin Song, Feng Yu, Hong Liu, Ning Cheng, Yunlong Li, Lianghai Jin, Chih-Cheng Hung
Iatrogenic injury of ureter occurs occasionally in the clinical laparoscopic surgery. The ureter injury may cause the serious complications and kidney damage. To avoid such an injury, it is necessary to detect the ureter position in real-time. Currently, the endoscope cannot perform this type of function in detecting the ureter position in real-time. In order to have the real-time display of ureter position during the surgical operation, we propose a novel endoscope system which consists of a modified endoscope light and a new lumiontron tube with the LED light...
December 2016: Journal of Medical Systems
Alice Brandli, Daniel M Johnstone, Jonathan Stone
Purpose: To test whether remote ischemic preconditioning (RIP) is protective to photoreceptors, in a light damage model, and to identify mechanisms involved. Methods: A pressure cuff was used to induce ischemia (2 × 5 minutes) in one hind limb of 4- to 6-month-old albino Sprague-Dawley rats raised in dim, cyclic light (12 hours 5 lux, 12 hours dark). Immediately following the ischemia, rats were exposed to bright continuous light (1000 lux) for 24 hours. After 7-day survival in dim, cyclic light conditions, retinal function was assessed using the flash electroretinogram (ERG) and retinal structure was examined for photoreceptor survival and death, as well as for stress...
October 1, 2016: Investigative Ophthalmology & Visual Science
Katarina Danielsson, Markus Jansson-Fröjmark, Jan-Erik Broman, Agneta Markström
Clinical trials with light therapy (LT) for delayed sleep phase disorder (DSPD) are sparse and little is known about factors that are favorable for improvements. In this study, LT with scheduled rise times was conducted at home for 14 days by 44 participants with DSPD aged 16-26 years. Primary outcomes were sleep onset and sleep offset. Potential predictors were demographic characteristics, chronotype, dim light melatonin onset, the number of days the LT lamp was used, the daily duration of LT, daytime sleepiness, anxiety, depression, worry, and rumination...
August 11, 2016: Behavioral Sleep Medicine
Patrycja Orlowska-Feuer, Jagoda S Jeczmien-Lazur, Hanna J Szkudlarek, Marian H Lewandowski
A subpopulation of olivary pretectal nucleus (OPN) neurons fire action potentials in a rhythmic manner with an eruption of activity occurring approximately every two minutes. These infra-slow oscillations depend critically on functional retinal input and are subject to modulation by light. Interestingly, the activity of photoreceptors is necessary for the emergence of the rhythm and while classic photoreceptors (rods and cones) are necessary in darkness and dim light, melanopsin photoreceptors are indispensable in bright light...
September 28, 2016: Neuroscience
Shery Goril, Dora Zalai, Louise Scott, Colin M Shapiro
OBJECTIVES: Caregivers describe significant sleep disturbances in the vast majority of children and adolescents, which is diagnosed as fetal alcohol spectrum disorders (FASD), but objective data on sleep disorders in this population are almost completely lacking. Animal models suggest that intrauterine alcohol exposure may disrupt sleep wake patterns, cause sleep fragmentation, and specifically affect the suprachiasmatic nucleus, thus disrupting melatonin secretion. The objective of this pioneering study was to evaluate sleep and melatonin abnormalities in children with FASD using objective, gold-standard measures...
July 2016: Sleep Medicine
Jade M Murray, Tracey L Sletten, Michelle Magee, Christopher Gordon, Nicole Lovato, Delwyn J Bartlett, David J Kennaway, Leon C Lack, Ronald R Grunstein, Steven W Lockley, Shantha M W Rajaratnam
STUDY OBJECTIVE: To examine the prevalence of circadian misalignment in clinically diagnosed DSPD, and compare mood and daytime functioning in those with and without a circadian basis for the disorder. METHODS: 182 DSPD patients aged 16 to 64 years, engaged in regular employment or school, underwent sleep-wake monitoring in the home, followed by a sleep laboratory visit for assessment of salivary dim light melatonin onset (DLMO). Based on the DLMO assessments, patients were classified into two groups: circadian DSPD, defined as DLMO occurring at or after desired bedtime, or non-circadian DSPD, defined as DLMO occurring before desired bedtime...
September 26, 2016: Sleep
Therese Reber, Marie Dacke, Eric Warrant, Emily Baird
To make a smooth touchdown when landing, an insect must be able to reliably control its approach speed as well as its body and leg position-behaviors that are thought to be regulated primarily by visual information. Bumblebees forage and land under a broad range of light intensities and while their behavior during the final moments of landing has been described in detail in bright light, little is known about how this is affected by decreasing light intensity. Here, we investigate this by characterizing the performance of bumblebees, B...
2016: Frontiers in Behavioral Neuroscience
L Maierova, A Borisuit, J-L Scartezzini, S M Jaeggi, C Schmidt, M Münch
Circadian rhythms in physiology and behavior are modulated by external factors such as light or temperature. We studied whether self-selected office lighting during the habitual waking period had a different impact on alertness, cognitive performance and hormonal secretion in extreme morning and evening chronotypes (N = 32), whose preferred bed- and wake-up times differed by several hours. The self-selected lighting condition was compared with constant bright light and a control condition in dim light. Saliva samples for hormonal analyses, subjective ratings of alertness, wellbeing, visual comfort and cognitive performance were regularly collected...
2016: Scientific Reports
Anja Kraneburg, Steffen Franke, Ralf Methling, Barbara Griefahn
UNLABELLED: We studied the influence of correlated color temperature (CCT) of 7 polychromatic white light illuminations (1600 K-14,000 K, 200 lx) in two experiments. Visual performance was tested in 17 students (8 men) during daytime. Visual acuity, contrast sensitivity and sleepiness did not vary with illuminations but polychromatic white light of <2000 K impaired color discrimination. Melatonin synthesis was tested with weekly intervals in 8 trials from 10pm to 2am (7 polychromatic illuminations and a dim light reference (<0...
January 2017: Applied Ergonomics
Nicole Lovato, Gorica Micic, Michael Gradisar, Sally A Ferguson, Helen J Burgess, David J Kennaway, Leon Lack
INTRODUCTION: The efficacy of bright light and/or melatonin treatment for Delayed Sleep Wake Phase Disorder (DSWPD) is contingent upon an accurate clinical assessment of the circadian phase. However, the process of determining this circadian phase can be costly and is not yet readily available in the clinical setting. The present study investigated whether more cost-effective and convenient estimates of the circadian phase, such as self-reported sleep timing, can be used to predict the circadian phase and guide the timing of light and/or melatonin treatment (i...
September 9, 2016: Chronobiology International
Yasmine M Cissé, Juan Peng, Randy J Nelson
Dim light at night (dLAN) disrupts circadian organization and influences adult behavior. We examined early dLAN exposure on adult affective responses. Beginning 3 (juvenile) or 5 weeks (adolescent) of age, mice were maintained in standard light-dark cycles or exposed to nightly dLAN (5 lx) for 5 weeks, then anxiety-like and fear responses were assessed. Hypothalami were collected around the clock to assess core clock genes. Exposure to dLAN at either age increased anxiety-like responses in adults. Clock and Rev-ERB expression were altered by exposure to dLAN...
September 3, 2016: Chronobiology International
Evan D Chinoy, Michael P Harris, Min Ju Kim, Wei Wang, Jeanne F Duffy
OBJECTIVES: We tested whether a sleep and circadian-based treatment shown to improve circadian adaptation to night shifts and attenuate negative effects on alertness, performance and sleep in young adults would also be effective in older adults. METHODS: We assessed subjective alertness, sustained attention (psychomotor vigilance task, PVT), sleep duration (actigraphy) and circadian timing (salivary dim-light melatonin onset, DLMO) in 18 older adults (57.2±3.8 years; mean±SD) in a simulated shift work protocol...
August 25, 2016: Occupational and Environmental Medicine
James Q Truong, Kenneth J Ciuffreda
PURPOSE: To determine if mTBI adversely affects the pupillary light reflex (PLR). METHODS: The PLR was evaluated in mTBI and compared to normal individuals under a range of test conditions. Nine pupil parameters (maximum, minimum and final pupil diameter, latency, amplitude and peak and average constriction and dilation velocities) and six stimulus conditions (dim pulse, dim step, bright pulse, bright step, bright red step and bright blue step) were assessed in 32 adults with mTBI (21-60 years of age) and compared to 40 normal (22-56 years of age)...
2016: Brain Injury: [BI]
Sandra Larcher, Anne-Sophie Gauchez, Sandrine Lablanche, Jean-Louis Pépin, Pierre-Yves Benhamou, Anne-Laure Borel
BACKGROUND: Sleep behavior is changing toward shorter sleep duration and a later chronotype. It results in a sleep debt that is acquitted on work-free days, inducing a small but recurrent sleep misalignment each week, referred to as "social jetlag". These sleep habits could affect health through misalignment with circadian rhythms. OBJECTIVES: The primary objective is to address the impact of sleep behavior on glycemic control, assessed by HbA1c, in patients with type 1 diabetes, independently of other lifestyle or sleep-related factors...
November 2016: European Journal of Endocrinology
Shuichi Ito, Shuho Hori, Makiko Hirose, Mari Iwahara, Azusa Yatsushiro, Atsushi Matsumoto, Masayuki Tanaka, Chinobu Okamoto, Ken-Ichi Yayou, Tsuyoshi Shimmura
The rhythmic locomotor behavior of flies and mice provides a phenotype for the identification of clock genes, and the underlying molecular mechanism is well studied. However, interestingly, when examining locomotor rhythm in the wild, several key laboratory-based assumptions on circadian behavior are not supported in natural conditions. The rooster crowing 'cock-a-doodle-doo' is a symbol of the break of dawn in many countries. Previously, we used domestic inbred roosters and showed that the timing of roosters' crowing is regulated by the circadian clock under laboratory conditions...
August 17, 2016: Animal Science Journal, Nihon Chikusan Gakkaihō
Iris Morag, Arne Ohlsson
BACKGROUND: Potential benefits and harms of different lighting in neonatal units have not been quantified. OBJECTIVES: • To determine effectiveness and safety of cycled light (CL) (approximately 12 hours of light on and 12 hours of light off) for growth in preterm infants at three and six months' corrected age (CA).• In separate analyses, to compare effects of CL with those of irregularly dimmed light (DL) or near darkness (ND), and effects of CL with those of continuous bright light (CBL), on growth in preterm infants at three and six months' CA...
2016: Cochrane Database of Systematic Reviews
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