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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
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
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
Belinda N Mandrell, Yvonne Avent, Breya Walker, Megan Loew, Brooklee Lightsey Tynes, Valerie McLaughlin Crabtree
In-home salivary collection quality and adherence to a prescribed collection methodology for evaluation of dim light melatonin onset (DLMO) is unknown in children. Primary aims of this study were to 1) describe a novel family centered methodology for in-home salivary collection; 2) determine the acceptance and feasibility of this methodology; 3) measure adherence to collection instructions; and 4) identify patterns between participants' age and quality of samples collected. After receiving instructional handouts from the study team, families utilized in-home salivary melatonin collection...
January 2018: Developmental Psychobiology
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
Shinobu Yasuo, Ayaka Iwamoto, Sang-Il Lee, Shotaro Ochiai, Rina Hitachi, Satomi Shibata, Nobuo Uotsu, Chie Tarumizu, Sayuri Matsuoka, Mitsuhiro Furuse, Shigekazu Higuchi
Background: The circadian clock is modulated by the timing of ingestion or food composition, but the effects of specific nutrients are poorly understood. Objective: We aimed to identify the amino acids that modulate the circadian clock and reset the light-induced circadian phase in mice and humans. Methods: Male CBA/N mice were orally administered 1 of 20 l-amino acids, and the circadian and light-induced phase shifts of wheel-running activity were analyzed. Antagonists of several neurotransmitter pathways were injected before l-serine administration, and light-induced phase shifts were analyzed...
December 2017: Journal of Nutrition
Michael R Dolsen, Allison G Harvey
PURPOSE: A shift toward an evening circadian preference and the onset of mood problems often occur during adolescence. Although these changes are linked to poorer outcomes, few studies have considered how positive and negative affect are related to the circadian rhythm during adolescence. This study examined the relationship between evening and morning affect ratings and dim light melatonin onset (DLMO), a measure of endogenous circadian rhythm. Age and sex were tested as moderators. METHODS: This study is based on a subset of 163 (94 female, age = 14...
October 19, 2017: Journal of Adolescent Health: Official Publication of the Society for Adolescent Medicine
Emma J Wams, Tom Woelders, Irene Marring, Laura van Rosmalen, Domien G M Beersma, Marijke C M Gordijn, Roelof A Hut
Study objectives: To determine the effect of light exposure on subsequent sleep characteristics under ambulatory field conditions. Methods: Twenty healthy participants were fitted with ambulatory PSG and wrist-actigraphs to assess light exposure, rest-activity, sleep quality, timing and architecture. Laboratory salivary dim-light melatonin onset (DLMO) was analyzed to determine endogenous circadian phase. Results: Later circadian clock phase was associated with lower intensity (R2=0...
October 11, 2017: Sleep
Erin E Flynn-Evans, Julia A Shekleton, Belinda Miller, Lawrence J Epstein, Douglas Kirsch, Lauren A Brogna, Liza M Burke, Erin Bremer, Jade M Murray, Philip Gehrman, Shantha M W Rajaratnam, Steven W Lockley
Objectives: We aimed to identify the prevalence of circadian phase and phase angle abnormalities in patients with insomnia. Methods: We conducted a cross-sectional, multicenter study at three sleep laboratories in the United States and Australia. Patients with insomnia and healthy control participants completed a sleep log for seven days. Circadian phase was assessed from salivary Dim Light Melatonin Onset (DLMO) time during a 12-hour laboratory visit. Results: Seventy-nine patients meeting the Research Diagnostic Criteria for Primary, Psychophysiological, Paradoxical, and/or Idiopathic Childhood Insomnia (46F, 35...
October 3, 2017: Sleep
Rébecca Robillard, Jim Lagopoulos, Daniel F Hermens, Sharon L Naismith, Naomi L Rogers, Django White, Joanne S Carpenter, Manreena Kaur, Elizabeth M Scott, Ian B Hickie
Myo-inositol, a second messenger glucose isomer and glial marker, is potentiated by melatonin. In addition to common abnormalities in melatonin regulation, depressive disorders have been associated with reduced myo-inositol in frontal structures. This study examined associations between myo-inositol in the anterior cingulate cortex and the timing of evening melatonin release. Forty young persons with unipolar depression were recruited from specialized mental health services (20.3 ± 3.8 years old). Healthy controls were recruited from the community (21...
2017: Frontiers in Neuroscience
Stephanie J Crowley, Charmane I Eastman
Older adolescents are particularly vulnerable to circadian misalignment and sleep restriction, primarily due to early school start times. Light can shift the circadian system and could help attenuate circadian misalignment; however, a phase response curve (PRC) to determine the optimal time for receiving light and avoiding light is not available for adolescents. We constructed light PRCs for late pubertal to postpubertal adolescents aged 14 to 17 years. Participants completed 2 counterbalanced 5-day laboratory sessions after 8 or 9 days of scheduled sleep at home...
August 2017: Journal of Biological Rhythms
Andrew J K Phillips, William M Clerx, Conor S O'Brien, Akane Sano, Laura K Barger, Rosalind W Picard, Steven W Lockley, Elizabeth B Klerman, Charles A Czeisler
The association of irregular sleep schedules with circadian timing and academic performance has not been systematically examined. We studied 61 undergraduates for 30 days using sleep diaries, and quantified sleep regularity using a novel metric, the sleep regularity index (SRI). In the most and least regular quintiles, circadian phase and light exposure were assessed using salivary dim-light melatonin onset (DLMO) and wrist-worn photometry, respectively. DLMO occurred later (00:08 ± 1:54 vs. 21:32 ± 1:48; p < 0...
June 12, 2017: Scientific Reports
Justyna Paprocka, Marek Kijonka, Łukasz Boguszewicz, Maria Sokół
Purpose. The aim of the study was to assess melatonin secretion pattern in children with TSC and to compare it with the secretion patterns in children with and without epilepsy. Material and Methods. Melatonin secretion was measured every three hours using the RIA method in four children with recognized TSC. The parameters of the melatonin secretion models were interpreted and compared with those obtained for the patients with epilepsy (n = 76) and the children from the control, nonepileptic group (n = 36)...
2017: International Journal of Endocrinology
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
Tom Woelders, Domien G M Beersma, Marijke C M Gordijn, Roelof A Hut, Emma J Wams
Light is the most potent time cue that synchronizes (entrains) the circadian pacemaker to the 24-h solar cycle. This entrainment process is an interplay between an individual's daily light perception and intrinsic pacemaker period under free-running conditions. Establishing individual estimates of circadian phase and period can be time-consuming. We show that circadian phase can be accurately predicted (SD = 1.1 h for dim light melatonin onset, DLMO) using 9 days of ambulatory light and activity data as an input to Kronauer's limit-cycle model for the human circadian system...
June 2017: Journal of Biological Rhythms
Emma K Baker, Amanda L Richdale, Agnes Hazi, Luke A Prendergast
This study assessed melatonin levels and the dim light melatonin onset (DLMO) in adults with Autism Spectrum Disorder (ASD) and also investigated the relationships between melatonin and objectively measured sleep parameters. Sixteen adults with ASD (ASD-Only), 12 adults with ASD medicated for comorbid diagnoses of anxiety and/or depression (ASD-Med) and 32 controls participated in the study. Although, the timing of the DLMO did not differ between the two groups, advances and delays of the melatonin rhythm were observed in individual profiles...
July 2017: Journal of Autism and Developmental Disorders
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
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...
February 1, 2017: Sleep
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 delayed sleep phase disorder (DSPD) and to compare mood and daytime functioning in those with and without a circadian basis for the disorder. Methods: One hundred and eighty-two DSPD patients aged 16-64 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)...
January 1, 2017: Sleep
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