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DLMO light at night

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...
April 2018: Journal of Biological Rhythms
Thomas Kantermann, Charmane I Eastman
The timing of the circadian clock, circadian period and chronotype varies among individuals. To date, not much is known about how these parameters vary over time in an individual. We performed an analysis of the following five common circadian clock and chronotype measures: 1) the dim light melatonin onset (DLMO, a measure of circadian phase), 2) phase angle of entrainment (the phase the circadian clock assumes within the 24-h day, measured here as the interval between DLMO and bedtime/dark onset), 3) free-running circadian period (tau) from an ultradian forced desynchrony protocol (tau influences circadian phase and phase angle of entrainment), 4) mid-sleep on work-free days (MSF from the Munich ChronoType Questionnaire; MCTQ) and 5) the score from the Morningness-Eveningness Questionnaire (MEQ)...
February 2018: Chronobiology International
Shunsuke Nagashima, Madoka Osawa, Hiroto Matsuyama, Wataru Ohoka, Aemi Ahn, Tomoko Wakamura
The guidelines for night and shift workers recommend that after night work, they should sleep in a dark environment during the daytime. However, staying in a dark environment during the daytime reduces nocturnal melatonin secretion and delays its onset. Daytime bright-light exposure after night work is important for melatonin synthesis the subsequent night and for maintaining the circadian rhythms. However, it is not clear whether daytime sleeping after night work should be in a dim- or a bright-light environment for maintaining melatonin secretion...
February 2018: Chronobiology International
Helen J Burgess, Margaret Park, James K Wyatt, Muneer Rizvydeen, Louis F Fogg
OBJECTIVE/BACKGROUND: To compare sleep and circadian variability in adults with delayed sleep-wake phase disorder (DSWPD) to healthy controls. PATIENTS/METHODS: Forty participants (22 DSWPD, 18 healthy controls) completed a ten-day protocol, consisting of DLMO assessments on two consecutive nights, a five-day study break, followed by two more DLMO assessments. All participants were instructed to sleep within one hour of their self-reported average sleep schedule for the last four days of the study break...
June 2017: Sleep Medicine
Shadab A Rahman, Melissa A St Hilaire, Anne-Marie Chang, Nayantara Santhi, Jeanne F Duffy, Richard E Kronauer, Charles A Czeisler, Steven W Lockley, Elizabeth B Klerman
BACKGROUND. In humans, a single light exposure of 12 minutes and multiple-millisecond light exposures can shift the phase of the circadian pacemaker. We investigated the response of the human circadian pacemaker to a single 15-second or 2-minute light pulse administered during the biological night. METHODS. Twenty-six healthy individuals participated in a 9-day inpatient protocol that included assessment of dim light melatonin onset time (DLMO time) before and after exposure to a single 15-second (n = 8) or 2-minute (n = 12) pulse of bright light (9,500 lux; 4,100 K fluorescent) or control background dim light (<3 lux; n = 6)...
April 6, 2017: JCI Insight
Shunsuke Nagashima, Makoto Yamashita, Chiaki Tojo, Masayuki Kondo, Takeshi Morita, Tomoko Wakamura
BACKGROUND: Tryptophan (TRP) is an essential amino acid, and it has been suggested that TRP intake at breakfast combined with daytime bright light exposure can increase nocturnal melatonin secretion. However, the mechanisms involved are not yet clear. The aim of this study was to examine the effect of TRP supplement intake at breakfast on nocturnal melatonin secretion under different daytime light intensities in humans. METHOD: Twelve subjects (aged 21.3 ± 3...
February 28, 2017: Journal of Physiological Anthropology
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...
December 2016: Occupational and Environmental Medicine
Garth R Swanson, Annika Gorenz, Maliha Shaikh, Vishal Desai, Thomas Kaminsky, Jolice Van Den Berg, Terrence Murphy, Shohreh Raeisi, Louis Fogg, Martha Hotz Vitaterna, Christopher Forsyth, Fred Turek, Helen J Burgess, Ali Keshavarzian
Alcohol-induced intestinal hyperpermeability (AIHP) is a known risk factor for alcoholic liver disease (ALD), but only 20-30% of heavy alcoholics develop AIHP and ALD. The hypothesis of this study is that circadian misalignment would promote AIHP. We studied two groups of healthy subjects on a stable work schedule for 3 mo [day workers (DW) and night workers (NW)]. Subjects underwent two circadian phase assessments with sugar challenge to access intestinal permeability between which they drank 0.5 g/kg alcohol daily for 7 days...
July 1, 2016: American Journal of Physiology. Gastrointestinal and Liver Physiology
Shigekazu Higuchi, Sang-il Lee, Tomoaki Kozaki, Tetsuo Harada, Ikuo Tanaka
Light is the strongest synchronizer of human circadian rhythms, and exposure to residential light at night reportedly causes a delay of circadian rhythms. The present study was conducted to investigate the association between color temperature of light at home and circadian phase of salivary melatonin in adults and children. Twenty healthy children (mean age: 9.7 year) and 17 of their parents (mean age: 41.9 years) participated in the experiment. Circadian phase assessments were made with dim light melatonin onset (DLMO)...
2016: Chronobiology International
Tracey L Sletten, Ahuva Y Segal, Erin E Flynn-Evans, Steven W Lockley, Shantha M W Rajaratnam
Although sleep restriction is associated with decrements in daytime alertness and neurobehavioural performance, there are considerable inter-individual differences in the degree of impairment. This study examined the effects of short-term sleep restriction on neurobehavioural performance and sleepiness, and the associations between individual differences in impairments and circadian rhythm phase. Healthy adults (n = 43; 22 M) aged 22.5 ± 3.1 (mean ± SD) years maintained a regular 8:16 h sleep:wake routine for at least three weeks prior to laboratory admission...
2015: PloS One
Marie Dumont, Jean Paquet
Decreased melatonin production, due to nighttime exposure to light, has been proposed as one of the physiological mechanisms increasing cancer risk in night workers. However, few studies measured melatonin production in night workers, and most of these studies did not measure melatonin over 24 h. One study compared total melatonin production between day and night shifts in rotating night workers and did not find significant differences. However, without baseline measures, it was not possible to exclude that melatonin production was reduced during both day and night work...
December 2014: Chronobiology International
Valentina Gumenyuk, Ryan Howard, Thomas Roth, Oleg Korzyukov, Christopher L Drake
STUDY OBJECTIVES: Permanent night-shift workers may develop shift-work disorder (SWD). In the current study, we evaluated neurophysiological and behavioral indices of distractibility across times prior to the night shift (T1), during night hours (T2), and after acute sleep deprivation (T3) in permanent hospital night workers with and without SWD. METHODS: Ten asymptomatic night workers (NW) and 18 NW with SWD participated in a 25-h sleep deprivation study. Circadian phase was evaluated by dim-light salivary melatonin onset (DLMO)...
March 1, 2014: Sleep
Valentina Gumenyuk, Thomas Roth, Christopher L Drake
Most night workers are unable to adjust their circadian rhythms to the atypical hours of sleep and wake. Between 10% and 30% of shiftworkers report symptoms of excessive sleepiness and/or insomnia consistent with a diagnosis of shift work disorder (SWD). Difficulties in attaining appropriate shifts in circadian phase, in response to night work, may explain why some individuals develop SWD. In the present study, it was hypothesized that disturbances of sleep and wakefulness in shiftworkers are related to the degree of mismatch between their endogenous circadian rhythms and the night-work schedule of sleep during the day and wake activities at night...
August 2012: Chronobiology International
Mariana G Figueiro, Mark S Rea
BACKGROUND: A previous study reported a method for measuring the spectral transmittance of individual human eyelids. A prototype light mask using narrow-band "green" light (λmax = 527 nm) was used to deliver light through closed eyelids in two within-subjects studies. The first study investigated whether an individual-specific light dose could suppress melatonin by 40% through the closed eyelid without disrupting sleep. The light doses were delivered at three times during the night: 1) beginning (while subjects were awake), 2) middle (during rapid eye movement (REM) sleep), and 3) end (during non-REM sleep)...
May 7, 2012: BMC Research Notes
Anne-Marie Chang, Nayantara Santhi, Melissa St Hilaire, Claude Gronfier, Dayna S Bradstreet, Jeanne F Duffy, Steven W Lockley, Richard E Kronauer, Charles A Czeisler
Light exposure in the early night induces phase delays of the circadian rhythm in melatonin in humans. Previous studies have investigated the effect of timing, intensity, wavelength, history and pattern of light stimuli on the human circadian timing system. We present results from a study of the duration–response relationship to phase-delaying bright light. Thirty-nine young healthy participants (16 female; 22.18±3.62 years) completed a 9-day inpatient study. Following three baseline days, participants underwent an initial circadian phase assessment procedure in dim light (<3 lux), and were then randomized for exposure to a bright light pulse (∼10,000 lux) of 0...
July 1, 2012: Journal of Physiology
Deirdre A Conroy, Ilana S Hairston, J Todd Arnedt, Robert F Hoffmann, Roseanne Armitage, Kirk J Brower
Sleep disturbances in alcohol-dependent (AD) individuals may persist despite abstinence from alcohol and can influence the course of the disorder. Although the mechanisms of sleep disturbances of AD are not well understood and some evidence suggests dysregulation of circadian rhythms, dim light melatonin onset (DLMO) has not previously been assessed in AD versus healthy control (HC) individuals in a sample that varied by sex and race. The authors assessed 52 AD participants (mean ± SD age: 36.0 ± 11...
February 2012: Chronobiology International
Barbara L Parry, Charles J Meliska, Diane L Sorenson, L Fernando Martínez, Ana M López, Jeffrey A Elliott, Richard L Hauger
The authors previously observed blunted phase-shift responses to morning bright light in women with premenstrual dysphoric disorder (PMDD). The aim of this study was to determine if these findings could be replicated using a higher-intensity, shorter-duration light pulse and to compare these results with the effects of an evening bright-light pulse. In 17 PMDD patients and 14 normal control (NC) subjects, the authors measured plasma melatonin at 30-min intervals from 18:00 to 10:00 h in dim (<30 lux) or dark conditions the night before (Night 1) and after (Night 3) a bright-light pulse (administered on Night 2) in both follicular and luteal menstrual cycle phases...
May 2011: Chronobiology International
Henry Keijzer, Marcel G Smits, Twan Peeters, Caspar W N Looman, Silvia C Endenburg, Jacqueline M T Klein Gunnewiek
BACKGROUND: Dim Light Melatonin Onset (DLMO) can be calculated within a 5-point partial melatonin curve in saliva collected at home. We retrospectively analyzed the patient melatonin measurements sample size of the year 2008 to evaluate these DLMO calculations and studied the correlation between diary or polysomnography (PSG) sleep onset and DLMO. METHODS: Patients completed an online questionnaire. If this questionnaire pointed to a possible Delayed Sleep Phase Disorder (DSPD), saliva collection devices were sent to the patient...
August 17, 2011: Clinica Chimica Acta; International Journal of Clinical Chemistry
Karuna Dewan, Susan Benloucif, Kathryn Reid, Lisa F Wolfe, Phyllis C Zee
STUDY OBJECTIVES: To evaluate the effect of increasing the intensity and/or duration of exposure on light-induced changes in the timing of the circadian clock of humans. DESIGN: Multifactorial randomized controlled trial, between and within subject design SETTING: General Clinical Research Center (GCRC) of an academic medical center PARTICIPANTS: 56 healthy young subjects (20-40 years of age) INTERVENTIONS: Research subjects were admitted for 2 independent stays of 4 nights/3 days for treatment with bright or dim-light (randomized order) at a time known to induce phase delays in circadian timing...
May 1, 2011: Sleep
Helen J Burgess
Partial sleep deprivation is increasingly common in modern society. This study examined for the first time if partial sleep deprivation alters circadian phase shifts to bright light in humans. Thirteen young healthy subjects participated in a repeated-measures counterbalanced design with 2 conditions. Each condition had baseline sleep, a dim-light circadian phase assessment, a 3-day phase-advancing protocol with morning bright light, then another phase assessment. In one condition (no sleep deprivation), subjects had an 8-h sleep opportunity per night during the advancing protocol...
December 2010: Journal of Biological Rhythms
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