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The response of Per1 to light in the suprachiasmatic nucleus of the diurnal degu (Octodon degus).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Several studies suggest that the circadian systems of diurnal mammals respond differently to daytime light than those of nocturnal mammals. We hypothesized that the photosensitive "clock" gene Per1 would respond to light exposure during subjective day in the suprachiasmatic nucleus of the diurnal rodent, Octodon degus. Tissue was collected 1.5-2 h after a 30 min light pulse presented at five timepoints across the 24 h day and compared to controls maintained under conditions of constant darkness. Per1 mRNA was quantified using in situ hybridization. Results showed that the rhythmicity and photic responsiveness of Per1 i...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Koch JM, Hagenauer MH, Lee TM Tags: Chronobiol Int Source Type: journals

Sleep quality in professional ballet dancers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Ballet dancers are competitive athletes who undergo extreme physical and mental stress and work according to an irregular schedule, with long days of training, rehearsal, and performance. Their most significant potential risks entail physical injury and altered sleep. The elaborate training requirements for ballet dancers do not allow regular chronobiological patterns or a normal sleep-wake rhythm. Our aim was to investigate the sleep-wake rhythm and sleep quality during rehearsal phases prior to a ballet premiere. We used wrist actigraphy and sleep diaries for a period of 67 days before the ballet premiere performance...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Fietze I, Strauch J, Holzhausen M, Glos M, Theobald C, Lehnkering H, Penzel T Tags: Chronobiol Int Source Type: journals

Morningness-eveningness, sex, and the Alternative Five Factor Model of personality.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Recent research on personality and circadian typology indicates that evening-type subjects are more extraverted, impulsive, and novelty-seeking, while morning ones tend to be more introverted, conscientious, agreeable, and emotionally stable. The purpose of this study was to examine the differences between circadian typologies on the Zuckerman's Alternative Five Factor Model of personality (AFFM), which has a strong biological basis, controlling for sex and age. A sample of 533 university students (168 men) participated in the study. Results showed that morning-type subjects had significant higher scores than evening-t...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Muro A, Gomà-i-Freixanet M, Adan A Tags: Chronobiol Int Source Type: journals

Sleep patterns in high school and university students: a longitudinal study.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We performed a longitudinal study to investigate whether changes in social zeitgebers and age alter sleep patterns in students during the transition from high school to university. Actimetry was performed on 24 high-school students (mean age+/-SD: 18.4+/-0.9 yrs; 12 females) for two weeks. Recordings were repeated in the same subjects 5 yrs later when they were university students. The sleep period duration and its center, the mid-sleep time, and total sleep time were estimated by actimetry. Actigraphic total sleep time was similar when in high school and at the university on school days (6.31+/-0.47 vs. 6.45+/-0.80 h,...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Urner M, Tornic J, Bloch KE Tags: Chronobiol Int Source Type: journals

Do restless legs syndrome (RLS) and periodic limb movements of sleep (PLMS) play a role in nocturnal hypertension and increased cardiovascular risk of renally impaired patients?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Hypertension can cause or promote renal failure and is related to cardiovascular mortality, the major cause of death in patients with renal impairment. Changes in the circadian BP pattern, particularly the blunting or reversal of the nocturnal decline in BP, are common in chronic renal failure. These changes in turn are among the major determinants of left ventricular hypertrophy. Using a chronobiological approach, it is possible to obtain better insight into the reciprocal relationship between hypertension, renal disease, and increased cardiovascular risk of renal patients. Disruption of the normal circadian rhythm of...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Portaluppi F, Cortelli P, Buonaura GC, Smolensky MH, Fabbian F Tags: Chronobiol Int Source Type: journals

Circadian pattern of ambulatory blood pressure in untreated hypertensive patients with and without metabolic syndrome.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
There is a strong association between metabolic syndrome (MS) and increased risk of end-organ damage, cardiovascular disease, stroke, and cardiovascular mortality. Moreover, non-dipping (<10% decline in the asleep relative to the awake blood pressure [BP] mean) and elevated ambulatory pulse pressure (PP), among other factors related to the circadian BP pattern, have also been associated with increased cardiovascular morbidity and mortality. This cross-sectional study investigated the circadian BP pattern in 2,045 non-diabetic untreated patients with uncomplicated essential hypertension (941 men/1,099 women), 48.7+/-...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Ayala DE, Hermida RC, Chayan L, Mojón A, Fontao MJ, Fernández JR Tags: Chronobiol Int Source Type: journals

Liver circadian clock, a pharmacologic target of cyclin-dependent kinase inhibitor seliciclib.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Circadian disruption accelerates malignant growth and shortens survival, both in experimental tumor models and cancer patients. In previous experiments, tumor circadian disruption was rescued with seliciclib, an inhibitor of cyclin-dependent kinases (CDKs). This effect occurred at a selective dosing time and was associated with improved antitumor activity. In the current study, seliciclib altered robust circadian mRNA expression of the clock genes Rev-erb alpha, Per2, and Bmal1 in mouse liver following dosing at zeitgeber time (ZT) 3 (i.e., 3 h after the onset of the 12 h light span), when mice start to rest, but not a...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Iurisci I, Filipski E, Sallam H, Harper F, Guettier C, Maire I, Hassan M, Iacobelli S, Lévi F Tags: Chronobiol Int Source Type: journals

Brain photoreceptor pathways contributing to circadian rhythmicity in crayfish.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Freshwater crayfish have three known photoreceptive systems: the compound eyes, extraretinal brain photoreceptors, and caudal photoreceptors. The primary goal of the work described here was to explore the contribution of the brain photoreceptors to circadian locomotory activity and define some of the underlying neural pathways. Immunocytochemical studies of the brain photoreceptors in the parastacid (southern hemisphere) crayfish Cherax destructor reveal their expression of the blue light-sensitive photopigment cryptochrome and the neurotransmitter histamine. The brain photoreceptors project to two small protocerebral ...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Sullivan JM, Genco MC, Marlow ED, Benton JL, Beltz BS, Sandeman DC Tags: Chronobiol Int Source Type: journals

Feeding entrainment of daily rhythms of locomotor activity and clock gene expression in zebrafish brain.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we investigate the existence of FAA in seven groups of zebrafish subjected to a light/dark (LD) cycle or constant light (LL) and different feeding regimes (random, fasting, and feeding in the middle of the light phase or dark phase). The aim was to ascertain whether the daily rhythm of behavior and clock gene (per1 and cry1) expression in the zebrafish brain was entrained by the light and feeding regime. The results revealed that FAA developed in zebrafish fed daily at a fixed time, under LD and under LL. Zebrafish displayed locomotor activity mostly during the daytime, although the percentage of activity du...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Sanchez JA, Sanchez-Vazquez FJ Tags: Chronobiol Int Source Type: journals

Melanopsin and clock genes: regulation by light and endothelin in the zebrafish ZEM-2S cell line.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
It is well known that clocks are present in brain regions other than the suprachiasmatic nucleus and in many peripheral tissues. In the teleost, Danio rerio, peripheral oscillators can be directly synchronized by light. Danio rerio ZEM-2S embryonic cells respond to light with differential growth: cells kept in constant light exhibited a strong inhibition of proliferation, whereas in cells kept in light:dark (LD) cycles (14L:10D and 10L:14D) or in constant darkness (DD), the doubling times were not statistically different. We demonstrated by RT-PCR followed by PCR that ZEM-2S cells express two melanopsins, Opn4x and Opn...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Farhat FP, Martins CB, De Lima LH, Isoldi MC, Castrucci AM Tags: Chronobiol Int Source Type: journals

Phase of the electrical activity rhythm in the SCN in vitro not influenced by preparation time.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The mammalian circadian clock, located in the suprachiasmatic nucleus (SCN) of the hypothalamus, drives daily rhythms in behavioral, physiological, and endocrine functions. The SCN has a genetic basis for rhythm generation and remains rhythmic when it is isolated and kept in constant conditions. This allows for an in vitro analysis of circadian attributes, which is a powerful approach in the study of SCN cellular mechanisms. For studying the phase of the SCN rhythm in vitro, it is important to assess whether preparation of the tissue itself introduces phase shifts. In the present study, we investigated whether preparat...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: vanderLeest HT, Vansteensel MJ, Duindam H, Michel S, Meijer JH Tags: Chronobiol Int Source Type: journals

Is light-at-night a health risk factor or a health risk predictor?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In 2007, the IARC (WHO) has classified "shift-work that involves circadian disruption" as potentially carcinogenic. Ample evidence leaves no doubt that shift-work is detrimental for health, but the mechanisms behind this effect are not well understood. The hormone melatonin is often considered to be a causal link between night shift and tumor development. The underlying "light-at-night" (LAN) hypothesis is based on the following chain of arguments: melatonin is a hormone produced under the control of the circadian clock at night, and its synthesis can be suppressed by light; as an indolamine, it potentially acts as a s...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Kantermann T, Roenneberg T Tags: Chronobiol Int Source Type: journals

Discoveries of rhythms in human biological functions: a historical review.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Though there are very early and ancient observations on the daily variation in physiological and pathophysiological functions (e.g., bronchial asthma), more detailed and scientific reports were not published until the beginning of the 17th century. The aim of this review is to bring those reports to the attention of researchers of chronobiology and chronopharmacology. The ancient books and their contents, which constitute the basis for this review, are part of the personal library collection of the author; numerous observations and reports on biologic rhythms in man are presented here for the first time. The intent of ...
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Lemmer B Tags: Chronobiol Int Source Type: journals

In memorium: Eugene L. Kanabrocki (April 18, 1922-April 23, 2009).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PMID: 19731104 [PubMed - in process]
Source: Chronobiology International - August 1, 2009 Category: Biology Authors: Sothern RB Tags: Chronobiol Int Source Type: journals

Assessment of chronotype in four- to eleven-year-old children: reliability and validity of the Children's Chronotype Questionnaire (CCTQ).Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study presents a detailed description of the assessment of children's chronotype by the Children's ChronoType Questionnaire (CCTQ). The CCTQ is a parent-report, 27-item mixed-format questionnaire resulting in multiple measures of chronotype in 4- to 11-yr-old children: the midsleep point on free days (MSF), a morningness/eveningness scale (M/E) score, and a five-point chronotype (CT) score. The study provides validity data using actigraphy as well as test-retest reliability data for all three chronotype measures and sleep/wake parameters. Overall, the findings indicate moderate to strong agreement between the three me...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Werner H, Lebourgeois MK, Geiger A, Jenni OG Tags: Chronobiol Int Source Type: journals

The tick-tock of language: is language processing sensitive to circadian rhythmicity and elevated sleep pressure?Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The master circadian pacemaker emits signals that trigger organ-specific oscillators and, therefore, constitutes a basic biological process that enables organisms to anticipate daily environmental changes by adjusting behavior, physiology, and gene regulation. Although circadian rhythms are well characterized on a physiological level, little is known about circadian modulations of higher cognitive functions. Thus, we investigated circadian repercussions on language performance at the level of minimal syntactic processing by means of German noun phrases in ten young healthy men under the unmasking conditions of a 40 h c...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Rosenberg J, Pusch K, Dietrich R, Cajochen C Tags: Chronobiol Int Source Type: journals

24-hour variation in the reactivity of rate-pressure-product to everyday physical activity in patients attending a hypertension clinic.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The exercise-related response of the rate-pressure-product (RPP) is a prognostic marker of autonomic imbalance, cardiovascular mortality, and silent myocardial ischemia in hypertension. In view of the well-known 24 h variation in out-of-hospital sudden cardiac events, our aim was to investigate whether the reactivity of RPP to everyday physical activities varies over the 24 h. Ambulatory measurements of systolic blood pressure (BP) and heart rate were recorded every 20 min for 24 h in 440 diurnally active patients attending a hypertension clinic. Wrist activity counts were summed over the 15 min that preceded a BP meas...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Atkinson G, Leary AC, George KP, Murphy MB, Jones H Tags: Chronobiol Int Source Type: journals

Cardiac autonomic neuropathy, estimated cardiovascular risk, and circadian blood pressure pattern in diabetes mellitus.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study was designed to investigate potential factors involved in the disruption of the circadian blood pressure (BP) pattern in diabetes mellitus, as well as the relation between BP, cardiac autonomic neuropathy, and estimated cardiovascular risk. We studied 101 diabetic patients (58% with type 2 diabetes; 59% men), age 21-65 yrs, evaluated by 48 h BP monitoring. We performed three autonomic tests in a single session: deep breathing, Valsalva maneuver, and standing up from a seated position. Patients were classified according to the number of abnormal tests and their 10 yr risk of coronary heart disease or stroke. The ...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Cabezas-Cerrato J, Hermida RC, Cabezas-Agricola JM, Ayala DE Tags: Chronobiol Int Source Type: journals

Shiftwork and impaired glucose metabolism: a 14-year cohort study on 7104 male workers.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The aim of this study was to assess the effect of shiftwork on hemoglobin A1c (HbA1c) level, as an index of glucose metabolism. A 14 yr prospective cohort study was conducted on day (n = 4219) and alternating shiftworkers (n = 2885) who received annual health checkups between 1991 and 2005 at a Japanese steel company. The endpoints were either a 10%, 15%, 20%, 25%, or 30% increase in HbA1c during the period of observation, compared to HbA1c at entry to the study. The association between the type of job schedule and increase in HbA1c was investigated after adjusting for age, body mass index, mean arterial pressure, tota...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Suwazono Y, Dochi M, Oishi M, Tanaka K, Kobayashi E, Sakata K Tags: Chronobiol Int Source Type: journals

Wearing blue-blockers in the morning could improve sleep of workers on a permanent night schedule: a pilot study.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Night shiftworkers often complain of disturbed sleep during the day. This could be partly caused by morning sunlight exposure during the commute home, which tends to maintain the circadian clock on a daytime rhythm. The circadian clock is most sensitive to the blue portion of the visible spectrum, so our aim was to determine if blocking short wavelengths of light below 540 nm could improve daytime sleep quality and nighttime vigilance of night shiftworkers. Eight permanent night shiftworkers (32-56 yrs of age) of Quebec City's Canada Post distribution center were evaluated during summertime, and twenty others (24-55 yr...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Sasseville A, Benhaberou-Brun D, Fontaine C, Charon MC, Hebert M Tags: Chronobiol Int Source Type: journals

Blue light exposure reduces objective measures of sleepiness during prolonged nighttime performance testing.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study examined the effects of nocturnal exposure to dim, narrowband blue light (460 nm, approximately 1 lux, 2 microW/cm2), compared to dim broad spectrum (white) ambient light ( approximately 0.2 lux, 0.5 microW/cm2), on subjective and objective indices of sleepiness during prolonged nighttime performance testing. Participants were also exposed to a red light (640 nm, approximately 1 lux, 0.7 microW/cm2) placebo condition. Outcome measures were driving simulator and psychomotor vigilance task (PVT) performance, subjective sleepiness, salivary melatonin, and electroencephalographic (EEG) activity. The study had a repe...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Phipps-Nelson J, Redman JR, Schlangen LJ, Rajaratnam SM Tags: Chronobiol Int Source Type: journals

Timing light treatment for eastward and westward travel preparation.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objective of the studies reported here was to determine, using a narrow bandwidth light tower (500 nm), the optimum timing of light treatment to hasten adaptive circadian phase advance and delay. Three counterbalanced treatment order, repeated measures studies were conducted to compare melatonin suppression and phase shift across multiple light treatment timings. In Experiment 1, 14 normal healthy volunteers (8 men/6 women) aged 34.9+/-8.2 yrs (mean+/-SD) underwent light treatment at the following times: A) 06:00 to 07:00 h, B) 05:30 to 07:30 h, and C) 09:00 to 10:00 h (active control). In Experiment 2, 13 normal healt...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Paul MA, Miller JC, Love RJ, Lieberman H, Blazeski S, Arendt J Tags: Chronobiol Int Source Type: journals

Daily and seasonal variation in the spectral composition of light exposure in humans.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Light is considered the most potent synchronizer of the human circadian system and exerts many other non-image-forming effects, including those that affect brain function. These effects are mediated in part by intrinsically photosensitive retinal ganglion cells that express the photopigment melanopsin. The spectral sensitivity of melanopsin is greatest for blue light at approximately 480 nm. At present, there is little information on how the spectral composition of light to which people are exposed varies over the 24 h period and across seasons. Twenty-two subjects, aged 22+/-4 yrs (mean+/-SD) participated during the w...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Thorne HC, Jones KH, Peters SP, Archer SN, Dijk DJ Tags: Chronobiol Int Source Type: journals

Daily rhythms of core temperature and locomotor activity indicate different adaptive strategies to cold exposure in adult and aged mouse lemurs acclimated to a summer-like photoperiod.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Daily variations in core temperature (Tc) within the normothermic range imply thermoregulatory processes that are essential for optimal function and survival. Higher susceptibility towards cold exposure in older animals suggests that these processes are disturbed with age. In the mouse lemur, a long-day breeder, we tested whether aging affected circadian rhythmicity of Tc, locomotor activity (LA), and energy balance under long-day conditions when exposed to cold. Adult (N = 7) and aged (N = 5) mouse lemurs acclimated to LD14/10 were exposed to 10-day periods at 25 and 12 degrees C. Tc and LA rhythms were recorded by te...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Terrien J, Zizzari P, Epelbaum J, Perret M, Aujard F Tags: Chronobiol Int Source Type: journals

Daily immediate early gene expression in the suprachiasmatic nucleus of male and female Octodon degus.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Diurnal and nocturnal species have different patterns of general activity, sleep-wake rhythms, and endocrine rhythms, but the mechanisms underlying these differences are not clear. Here, we tested the hypothesis that rhythms in immediate early gene (IEG) products in the suprachiasmatic nucleus (SCN) of a diurnal rodent (Octodon degus) reflect their diurnal chronotype. We also compared male and female degus with respect to temporal patterns of expression of one of these gene products, Fos-related Antigen (FRA). Animals were killed across the light:dark cycle, brains were collected, and sections through the SCN were stai...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Mahoney MM, Smale L, Lee TM Tags: Chronobiol Int Source Type: journals

Differential effects of a restricted feeding schedule on clock-gene expression in the hypothalamus of the rat.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Restricted feeding schedules (RFS) entrain digestive, hormonal, and metabolic functions as well as oscillations of clock genes, such as Per1 and Per2, in peripheral organs. In the brain, in particular the hypothalamus, RFS induce and shift daily rhythms of Per1 and Per2 expression. To determine whether RFS affect clock genes in extra-SCN oscillators in a uniform manner, the present study investigated daily rhythms of Per1, Per2, and Bmal1 expression in various hypothalamic regions. Wistar rats were entrained to daily RFS (2 h food access starting at ZT6, RFS) or fed ad libitum (C) for three weeks. Brains were sampled e...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Minana-Solis MC, Angeles-Castellanos M, Feillet C, Pevet P, Challet E, Escobar C Tags: Chronobiol Int Source Type: journals

Differential resetting process of circadian gene expression in rat pineal glands after the reversal of the light/dark cycle via a 24 h light or dark period transition.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Although studies involving the circadian response to time-zone transitions indicate that the circadian clock usually takes much longer to phase advance than delay, the discrepancy between the circadian resetting induced by photoperiod alteration via a dark or light period transition has yet to be investigated. In mammals, the pineal gland is an important component in the photoneuroendocrine axis, regulating biological rhythms. However, few studies have systematically examined the resetting process of pineal clock-gene expression to date. We investigated the resetting processes of four clock genes (Bmal1, Cry1, Per1, De...
Source: Chronobiology International - July 1, 2009 Category: Biology Authors: Wu T, Dong Y, Yang Z, Kato H, Ni Y, Fu Z Tags: Chronobiol Int Source Type: journals

Chronotype and body composition in bipolar disorder.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
We explored whether obesity in patients with bipolar disorder is associated with their chronotype. A group of 29 patients with bipolar I disorder, not currently experiencing an affective episode, were assessed for total body fat, mood symptoms, and self-reported circadian chronotype and sleep quality. Chronotype explained 19% of the variance in body fat, after age, sex, mood state, and sleep quality were accounted for. This association suggested that evening chronotype patients have a higher percentage of total body fat. Evening chronotype could be a proxy for as yet unknown specific causes of the high rate of obesity ...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Soreca I, Fagiolini A, Frank E, Goodpaster BH, Kupfer DJ Tags: Chronobiol Int Source Type: journals

Blue-light phase shifts PER3 gene expression in human leukocytes.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The timing of clock gene expression in human leukocytes was investigated following a phase-advancing light stimulus to determine whether the response is wavelength- and/or age-dependent. PERIOD3 (PER3) clock gene expression in leukocytes and plasma melatonin were analyzed before and after monochromatic blue and green light exposure. Significant phase advances were observed in the peak timing of both PER3 expression and melatonin following blue but not green light. The amplitude of the PER3 rhythm at baseline was significantly reduced with age. However, age did not affect the response of the PER3 rhythm to light. PM...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Ackermann K, Sletten TL, Revell VL, Archer SN, Skene DJ Tags: Chronobiol Int Source Type: journals

Effects of one night of partial sleep deprivation upon diurnal rhythms of accuracy and consistency in throwing darts.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Sixty subjects were tested five times per waking day on two occasions for accuracy and reliability in throwing 20 darts at a target. Two experimental conditions were investigated: following a normal nocturnal sleep (7-8 h sleep, normal) and after having retired to bed 4 h later than normal the previous night but rising at the normal time (3-4 h sleep, sleep deprivation). Sublingual (core) temperature and subjective estimates of alertness and fatigue were measured in all sessions. Performance at throwing darts was assessed by three methods: mean distance of the dart from the bulls-eye; number of times the target was mis...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Edwards BJ, Waterhouse J Tags: Chronobiol Int Source Type: journals

Persistent rotating shift-work exposure accelerates development of metabolic syndrome among middle-aged female employees: a five-year follow-up.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In conclusion, persistent day-night rotating shift work, smoking, and baseline metabolic syndrome components associate with the progression toward metabolic syndrome for middle-aged female workers. PMID: 19444753 [PubMed - in process]
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Lin YC, Hsiao TJ, Chen PC Tags: Chronobiol Int Source Type: journals

A personal light-treatment device for improving sleep quality in the elderly: dynamics of nocturnal melatonin suppression at two exposure levels.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Light treatment has been used as a non-pharmacological tool to help mitigate poor sleep quality frequently found in older people. In order to increase compliance to non-pharmacological light treatments, new, more efficacious light-delivery systems need to be developed. A prototype personal light-treatment device equipped with low brightness blue light-emitting diodes (LEDs) (peak wavelength near 470 nm) was tested for its effectiveness in suppressing nocturnal melatonin, a measure of circadian stimulation. Two levels of corneal irradiance were set to deliver two prescribed doses of circadian light exposure. Eleven olde...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Figueiro MG, Bierman A, Bullough JD, Rea MS Tags: Chronobiol Int Source Type: journals

Phase delaying the human circadian clock with blue-enriched polychromatic light.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The human circadian system is maximally sensitive to short-wavelength (blue) light. In a previous study we found no difference between the magnitude of phase advances produced by bright white versus bright blue-enriched light using light boxes in a practical protocol that could be used in the real world. Since the spectral sensitivity of the circadian system may vary with a circadian rhythm, we tested whether the results of our recent phase-advancing study hold true for phase delays. In a within-subjects counterbalanced design, this study tested whether bright blue-enriched polychromatic light (17000 K, 4000 lux) could...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Smith MR, Eastman CI Tags: Chronobiol Int Source Type: journals

Plasma corticosterone in rats is specifically increased at recovery from propofol anesthesia without concomitant rise of plasma ACTH.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
General anesthesia combined with surgery is commonly associated with post-operative stress-response in humans. Effects on the hypothalamic-pituitary-adrenal axis (HPA) during and after anesthesia are correlated with the magnitude of surgery and choice of anesthetics. The aim of our study in rats was to characterize the effects of general anesthesia without any surgery on HPA regulation of corticosterone and adrenocorticotropic hormone (ACTH) secretions. First, to assess whether the acute effects of general anesthesia on corticosterone concentration depend on time of day, rats were anesthetized with propofol at three di...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Dispersyn G, Sage D, Challet E, Pain L, Touitou Y Tags: Chronobiol Int Source Type: journals

Sleep deprivation in the dark period does not impair memory in OF1 mice.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
There is increasing evidence that sleep facilitates memory acquisition and consolidation. Moreover, the sleep-wake history preceding memory acquisition and retention as well as circadian timing may be important. We showed previously that sleep deprivation (SD) following learning in OF1 mice impaired their performance on an object recognition task. The learning task was scheduled at the end of the 12 h dark period and the test 24 h later. To investigate the influence of the prominent circadian sleep-wake distribution typical for rodents, we now scheduled the learning task at the beginning of the dark period. Wakefulness...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Palchykova S, Winsky-Sommerer R, Tobler I Tags: Chronobiol Int Source Type: journals

Circadian rhythms of locomotor activity in the Nile tilapia Oreochromis niloticus.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Behavioral rhythms of the Nile tilapia were investigated to better characterize its circadian system. To do so, the locomotor activity patterns of both male and female tilapia reared under a 12:12 h light-dark (LD) cycle were studied, as well as in males the existence of endogenous rhythmicity under free-running conditions (DD and 45 min LD pulses). When exposed to an LD cycle, the daily pattern of activity differed between individuals: some fish were diurnal, some nocturnal, and a few displayed an arrhythmic pattern. This variability would be typical of the plastic circadian system of fish. Moreover, reproductive even...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Vera LM, Cairns L, Sánchez-Vázquez FJ, Migaud H Tags: Chronobiol Int Source Type: journals

Synchronization of Indian weaver bird circadian rhythms to food and light zeitgebers: role of pineal.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study investigates the relative strengths of food and light zeitgebers in synchronization of circadian rhythms of Indian weaver birds and the role of the pineal gland in food-induced synchronization of the circadian activity rhythms. Two experiments were performed. In the first experiment, six birds were concurrently exposed for 10 days to PA 12/12 (12 h food present: 12 h food absent) and LD 12/12 (12 h light: 12 h dark). Then, the PA 12/12 cycle was reversed: food was present during the dark period of the LD 12/12 cycle. After 15 days, birds were released into constant dim light (LL(dim)). During exposure to overlap...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Rani S, Singh S, Malik S, Singh J, Kumar V Tags: Chronobiol Int Source Type: journals

Myocardial infarction occurs with a similar 24 h pattern in the 4G/5G versions of plasminogen activator inhibitor-1.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
PAI-1 expression is regulated by a 4G/5G promoter polymorphism. The 4G allele is associated with greater circadian variation of PAI-1 levels. We hypothesized that the 24 h variation of cardiac risk is more pronounced among persons with the 4G4G genotype than among ones with 4G5G and 5G5G genotypes. We assessed the time of onset of symptoms in 623 consecutive patients with acute myocardial infarction (AMI) enrolled in the MISSION! Study between February 1, 2004, and October 29, 2006. All of the patients were genotyped for the PAI-1 4G/5G polymorphism. We quantified the amplitude of the 24 h variation of AMI with a gener...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Bergheanu SC, Pons D, Jukema JW, van der Hoeven BL, Liem SS, Vandenbroucke JP, Rosendaal FR, le Cessie S, Schalij MJ, van der Bom JG Tags: Chronobiol Int Source Type: journals

Clock genes display rhythmic expression in human hearts.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this study, we analyzed the expression of clock genes in human hearts. Left papillary muscles of 16 patients with coronary heart disease, 39 subjects with cardiomyopathy, and 9 healthy donors (52 males and 12 females, mean age 55.7+/-11.2; 16-70 yrs) were obtained during orthotopic heart transplantation. We assessed the mRNA levels of PER1, PER2, BMAL1, and CRY1 by real time PCR and analyzed their rhythmic expression by sliding means and Cosinor functions. Furthermore, we sought for differences between the three groups (by ANOVAs) for both the total 24 h period and separate time bins. All four clock genes were expressed...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Leibetseder V, Humpeler S, Svoboda M, Schmid D, Thalhammer T, Zuckermann A, Marktl W, Ekmekcioglu C Tags: Chronobiol Int Source Type: journals

Temporal gradient in the clock gene and cell-cycle checkpoint kinase Wee1 expression along the gut.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Circadian clocks were recently discovered in the rat and mouse colon as well as mouse stomach and jejunum. The aim of this study was to determine whether clocks in the upper part of the gut are synchronized with those in the lower part, or whether there is a difference in their circadian phases. Moreover, the profiles of core clock-gene expression were compared with the profiles of the clock-driven Wee1 gene expression in the upper and lower parts of the gut. Adult rats were transferred to constant darkness on the day of sampling. 24 h expression profiles of the clock genes Per1, Per2, Rev-erbalpha, and Bmal1 and the c...
Source: Chronobiology International - May 1, 2009 Category: Biology Authors: Polidarová L, Soták M, Sládek M, Pacha J, Sumová A Tags: Chronobiol Int Source Type: journals

Circadian variations in the kinematics of handwriting and grip strength.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The present study determined whether the motor process of handwriting is influenced by a circadian rhythm during writing tasks of high everyday relevance and analyzed the relationship to the circadian rhythm of grip strength. Ten healthy young male subjects underwent a 40 h sleep-deprivation protocol under constant routine conditions. Starting at 09:00 h, subjects performed three handwriting tasks of increasing perceptual-motor complexity (writing a sentence, writing one's signature, and copying a text for 3 min) and assessed grip strength of both hands every 3 h. Handwriting performance was analyzed by writing speed, ...
Source: Chronobiology International - April 1, 2009 Category: Biology Authors: Jasper I, Haussler A, Baur B, Marquardt C, Hermsdorfer J Tags: Chronobiol Int Source Type: journals

Human Core Temperature Responses during Exercise and Subsequent Recovery: An Important Interaction between Diurnal Variation and Measurement Site.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Chronobiological investigations into core temperature during and after exercise can involve ambulatory measurements of intestinal temperature during actual competitions, esophageal temperature measurements in laboratory simulations, or rectal temperature, which can be measured in both the field and laboratory. These sites have yet to be compared during both morning and afternoon exercise and subsequent recovery. At 08:00 and 17:00 h, seven recreationally active males exercised at 70% peak oxygen uptake for 30 min and then recovered passively for 30 min. During the experiment, esophageal, rectal, intestinal, and skin te...
Source: Chronobiology International - April 1, 2009 Category: Biology Authors: Morris C, Atkinson G, Drust B, Marrin K, Gregson W Tags: Chronobiol Int Source Type: journals

Shift work and metabolic syndrome: respective impacts of job strain, physical activity, and dietary rhythms.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The objectives of this study were to evaluate the impact of shift work on metabolic syndrome according to two different definitions in a population of strictly rotating shift workers (3x8 h) compared to paired counterparts working only day hours, and to study whether shift work itself is a determinant of metabolic syndrome after taking into account a large panel of confusing factors. We conducted a cross-sectional study comparing 98 strictly rotating shift workers to 100 regular day-workers (all subjects had a long experience of their working rhythms) within the same petrochemical plant. Clinical, behavioral, occupational,...
Source: Chronobiology International - April 1, 2009 Category: Biology Authors: Esquirol Y, Bongard V, Mabile L, Jonnier B, Soulat JM, Perret B Tags: Chronobiol Int Source Type: journals

Effects of a two-hour change in bedtime on the sleep of healthy seniors.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Some of the sleep disruption seen in seniors (>65 yrs) may be due to alteration of the circadian pacemaker phase and/or its phase angle with bedtime. The purpose of this study was to determine the effects of 2 h changes in the timing of bedtime (both earlier and later) on the sleep of seniors. Ten healthy seniors (9 F, 1 M, age 70-82 yrs) were each studied individually during three 120 h sessions (each separated by >2 weeks) in a time-isolation laboratory. On nights 1 and 2, bedtime and rise-time occurred at the subjects' habitual times; on nights 3-5, bedtime was specified by the experiment, but rise-time was at...
Source: Chronobiology International - April 1, 2009 Category: Biology Authors: Monk TH, Buysse DJ, Begley AE, Billy BD, Fletcher ME Tags: Chronobiol Int Source Type: journals

In sync with the family: children and partners influence the sleep-wake circadian rhythm and social habits of women.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
This study suggests children have a strong influence on their mother's lifestyle and sleep-wake rhythm, far beyond the first months of life, and that children are a more important social factor than the male partner. PMID: 19360493 [PubMed - in process]
Source: Chronobiology International - April 1, 2009 Category: Biology Authors: Leonhard C, Randler C Tags: Chronobiol Int Source Type: journals

Morningness or morning affect? A short composite scale of morningness.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
The Composite Scale of Morningness (CSM) is a widely used measure of behavioral temporal preference, and it is highly reliable across cultures. There are several competing models concerning its factor structure. We used confirmatory factor analysis (CFA) to replicate the two-and three-factor models, and, in addition, we examined the utility of the four-item morning affect scale as a proxy for the full CSM. We tested these models in a large student sample (N=1396). The chi-square result for the two- and three-factor models indicated they did not adequately fit the data, and the modification indices suggested some items ...
Source: Chronobiology International - April 1, 2009 Category: Biology Authors: Di Milia L, Bohle P Tags: Chronobiol Int Source Type: journals

Phase Angle of Entrainment in Morning- and Evening-Types under Naturalistic Conditions.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Differences in morningness-eveningness among humans are commonly ascribed to circadian parameters, such as circadian period and responsivity to environmental time cues, as well as homeostatic sleep drive. Light is the primary synchronizer of the human biological clock, and if circadian differences exist between morning and evening types, they should have different phase angles of entrainment to the light/dark cycle; that is, morning and evening types should have different patterns of light exposure relative to endogenous circadian phase (ECP). When phase angle of entrainment is strictly defined as the relationship betw...
Source: Chronobiology International - April 1, 2009 Category: Biology Authors: Emens JS, Yuhas K, Rough J, Kochar N, Peters D, Lewy AJ Tags: Chronobiol Int Source Type: journals

Association between Specific Diurnal Preference Questionnaire Items and PER3 VNTR Genotype.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Although there are significant intra-individual differences in self-reported diurnal preference, as measured by validated questionnaires, the relative contribution of exogenous and endogenous factors to self-reported diurnal preference largely remains to be investigated. The present study examined which items from the Horne-Ostberg (HO) questionnaire of diurnal preference were better at predicting genotypes in the variable number tandem polymorphism (VNTR) in the coding region of the gene PER3. This polymorphism has previously been reported to associate with diurnal preference, sleep parameters, and cognitive performan...
Source: Chronobiology International - April 1, 2009 Category: Biology Authors: Ellis J, von Schantz M, Jones KH, Archer SN Tags: Chronobiol Int Source Type: journals

Iron deficiency alters the day-night variation in monoamine levels in mice.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
In this report, we examined changes in intracellular and extracellular monoamine levels, synthetic enzymes, transporter and receptor densities, and responses to amphetamine-induced dopamine (DA) efflux in iron-deficient and iron-sufficient mice. Extracellular striatal DA levels were 15-20% higher in all groups during the active dark phase compared to the inactive light phase, with correspondingly lower dopamine transporter (DAT) and higher tyrosine hydroxylase levels. Iron deficiency decreased DAT density by 20% and 28% in the light and dark phases, respectively, and elevated the DOPAC/DA ratio only in the dark, indicating...
Source: Chronobiology International - April 1, 2009 Category: Biology Authors: Bianco LE, Unger EL, Earley CJ, Beard JL Tags: Chronobiol Int Source Type: journals

Plasticity of circadian activity and body temperature rhythms in golden spiny mice.Email this article to a colleague. Save this article to My Clippings. Discuss or comment on this article.
Most animals can be categorized as nocturnal, diurnal, or crepuscular. However, rhythms can be quite plastic in some species and vary from one individual to another within a species. In the golden spiny mouse (Acomys russatus), a variety of rhythm patterns have been seen, and these patterns can change considerably as animals are transferred from the field into the laboratory. We previously suggested that these animals may have a circadian time-keeping system that is fundamentally nocturnal and that diurnal patterns seen in their natural habitat reflect mechanisms operating outside of the basic circadian time-keeping sy...
Source: Chronobiology International - April 1, 2009 Category: Biology Authors: Cohen R, Smale L, Kronfeld-Schor N Tags: Chronobiol Int Source Type: journals