Showing papers on "Morning published in 2000"
TL;DR: The interaction with outward anger expression suggests that individual characteristics modulate the impact of chronic work stress on the hypothalamic-pituitary-adrenocortical system.
Abstract: OBJECTIVE: The objectives of this study were to test the hypothesis that high job demands and low job control (job strain) are associated with elevated free cortisol levels early in the working day and with reduced variability across the day and to evaluate the contribution of anger expression to this pattern. METHODS: One hundred five school teachers (41 men and 64 women) classified 12 months earlier as high (N = 48) or low (N = 57) in job strain according to the demand/control model sampled saliva at 2-hour intervals from 8:00 to 8:30 hours to 22:00 to 22:30 hours on a working day. Anger expression was assessed with the Speilberger State-Trait Anger Expression Inventory, and negative affect was also measured. RESULTS: Free cortisol was significantly elevated at 8:00 to 8:30 hours in the high job strain group but not at later times of the day or evening. After adjustment for age and negative affect, cortisol was an average of 21.7% higher early in the working day in the high job strain group. This effect was significantly greater in high job strain teachers, who also reported high anger-out. The cortisol decline from morning to evening was greater in the high than low job strain individuals. Independently of job strain, women had a higher cortisol concentration at 8:00 to 8:30 hours than men, whereas cortisol concentration was greater in men than women in the middle of the working day between 12:00 and 16:30 hours. CONCLUSIONS: Job strain is associated with elevated free cortisol concentrations early in the working day but not with reduced cortisol variability. The interaction with outward anger expression suggests that individual characteristics modulate the impact of chronic work stress on the hypothalamic-pituitary-adrenocortical system.
357 citations
TL;DR: Slowly rotating shifts have the least negative impact on sleep length of shift-work schedules including a night shift, however, permanent night shifts could be an alternative shift- work schedule in operational settings that require many workers at night.
Abstract: Study objectives The current study used the meta-analytic technique to quantitatively assess the effects of permanent and rotating shift-work schedules on sleep length. Design A meta-analysis was completed on 36 primary studies resulting in 165 effect sizes. Effect sizes comparing shift-workers to a permanent day shift control group were calculated for permanent evening shifts, permanent night shifts, and morning, evening, and night shifts worked as part of slowly and rapidly rotating shift systems. Setting NA PATIENTS OR PARTICIPANTS: NA INTERVENTIONS: NA RESULTS: Permanent night shifts resulted in a decrease, whereas permanent evening shifts resulted in an increase in sleep length. The shifts within rotating schedules followed the same pattern, with the addition of morning shifts having a moderate detrimental effect on sleep length. Furthermore, the speed of shift rotation had an impact. Slowly rotating shifts, in general, had the least detrimental effect on sleep length of the permanent and rotating shift-work schedules studied here. The pattern of effects among morning, evening, and night shifts was the same for rapidly and slowly rotating shifts, with night shifts having the greatest detrimental effect, morning shifts having a moderate detrimental effect and evening shifts having a positive effect on sleep length. In addition, nights on rotating shifts had a greater negative effect on sleep length than permanent night shifts. Conclusions Slowly rotating shifts have the least negative impact on sleep length of shift-work schedules including a night shift. However, permanent night shifts could be an alternative shift-work schedule in operational settings that require many workers at night.
271 citations
TL;DR: Valyl-Tyrosine appeared to have a significant antihypertensive effect on mild hypertensive subjects via ang i-converting enzyme inhibition, as well as shr, but no adverse effects could be detected at all.
Abstract: The present study was conducted to determine whether Valyl-Tyrosine (VY) has an antihypertensive effect on high-normal blood pressure and mild essential hypertension, as well as spontaneous hypertensive rats (SHR). A randomised double-blind placebo-controlled study was carried out on 29 volunteers. A 100-ml drink containing 3 mg of VY and a 100-ml placebo drink were prepared. The subjects were grouped as VY(16M/1F, 45.5 +/- 3.2 years, 146.4 +/- 2.3/90.5 +/- 1.8 mm Hg) and the placebo (P) (11 M/1F, 48.8 +/- 3.0 years, 145.5 +/- 2.4/92.3 +/- 1.8 mm Hg). At 3 weeks of the control (C) period, a VY- or P-drink was administered twice a day for 4 weeks in the experimental (E) period and during the 4-week recovery period, neither drink was given to either group. Blood pressure (BP) was measured every week in the morning in the sitting position. Blood specimens were taken on the last day of the C and E periods. In the VY-group, reduction in systolic (S) and diastolic (D) BP was 9.7 and 5.3 mm Hg (P < 0. 001) at 1 week, and 9.3 and 5.2 mm Hg (P < 0.001) at 4 weeks, following the start of the E period, respectively. Neither SBP nor DBP changed in the P-group. BP in the VY-group increased gradually by the end of the recovery period. Plasma angiotensin (Ang) I and VY concentrations significantly increased while Ang II and aldosterone significantly decreased after VY administration in the VY-group. VY appeared to have a significant antihypertensive effect on mild hypertensive subjects via Ang I-converting enzyme inhibition, as well as SHR, but no adverse effects could be detected at all.
230 citations
TL;DR: The sexual dimorphism in the phase of the morning peak under LDconditions suggests that the function of activity during morning and evening peak might be different, for example, during themorning peak, males are active to find females and in two of the three strains, females were more active than males.
Abstract: The rhythms of locomotor activity of male and virgin or mated female flies were compared in the Drosophila melanogaster wild-type strains CantonS, Berlin, and OregonR. Under light-dark conditions, most flies showed a bimodal activity pattern with a morning peak around lights-on and an evening peak before lights-off. For all strains, a distinct sexual dimorphism was observed in the phase of the morning peak. Males had a significantly earlier morning peak than females and consequently a larger phase angle between morning and evening peak (psi(m, e)). Under constant dark conditions, the morning component merged with the evening component to a unimodal activity band in about half of the flies. In those flies who maintained bimodality, the sex-specific difference in psi(m, e) disappeared. Other sex-specific differences were now apparent: Males showed a shorter free-running period than females, and in two of the three strains, females were more active than males. Morning and evening components seem to contribute to the free-running period. Spontaneous or externally provoked change in psi(m, e) were correlated with period changes. In some flies, the morning and the evening components showed splitting, indicating that they are the output of two different oscillators. The sexual dimorphism in the phase of the morning peak under LD-conditions suggests that the function of activity during morning and evening peak might be different, for example, during the morning peak, males are active to find females. Overall, the results underline the multioscillatory nature of Drosophila's circadian system.
199 citations
TL;DR: The daily pattern of spontaneous eye-blink rate, a non-invasive peripheral measure of central dopamine activity, was investigated in 24 healthy subjects and a significant increase was found at the evening time point, suggestive of a late evening increase ofcentral dopamine activity.
Abstract: The daily pattern of spontaneous eye-blink rate (BR), a non-invasive peripheral measure of central dopamine activity, was investigated in 24 healthy subjects. The spontaneous eye-blink rate showed a stable pattern in morning, midday and afternoon hours. A significant increase was found at the evening time point (20.30 h). The finding is suggestive of a late evening increase of central dopamine activity. An increased level of subjective sleepiness was also found at the same evening point, at a time corresponding to the ‘evening wake maintenance zone’ or the ‘forbidden zone for sleep’. A possible hypothesis is that the ‘forbidden zone for sleep’ may reflect a dopamine-mediated activation that counteracts a rising sleep drive. The role of diurnal variation of dopamine function should be considered both in the choice of the drug treatment regimen, and in the evaluation of biological and neuropsychological parameters.
189 citations
TL;DR: Measured drug adherence diminishes significantly when treating children with mild asthma in a long term trial, and emphasises the importance of monitoring compliance in clinical trials.
Abstract: AIM—To measure drug adherence in children with mild asthma receiving long term prophylactic treatment.
METHODS—Double blind randomised placebo controlled trial. Patients received inhaled budesonide 100 µg or 200 µg daily, or placebo for 27 months. All participants were asked to inhale medication or placebo from two different Turbuhalers (morning and evening) during the study. A total of 122 children (80 boys, 42 girls) aged 7-16 years with mild asthma (mean FEV1 103.7% of predicted) were included in the trial. Drug adherence was assessed by counting the number of remaining doses in the inhaler when study medication was returned at six month intervals.
RESULTS—A statistically significant and continuing decrease in measured drug adherence was found from three to nine months and then to 27 months, reaching mean values of 40.6% and 46.9% for inhaled morning and evening medication respectively. Drug adherence declined more rapidly in the placebo group (compared to active treatment); this difference became significant after two years of treatment. Children aged 9 years or less had better drug adherence during the entire study period, but the difference was only significant for the first three months of the study. Measured drug adherence was significantly higher for evening medication compared to morning medication for all study intervals after nine months.
CONCLUSION—Measured drug adherence diminishes significantly when treating children with mild asthma in a long term trial. This emphasises the importance of monitoring compliance in clinical trials.
164 citations
TL;DR: The results show that circadian rhythmicity of UI in adults and children was found independent of the individual subject, age, gender, and season.
Abstract: Our overall aim is to monitor iodine supply in a prospective study before and after the September 1998 increase of salt iodide content in Switzerland. Because iodide is supplied by alimentation, we moreover wondered whether urinary iodine concentration (UI) is governed by circadian rhythmicity. Forty-two subjects (18 males and 24 females, including 13 children) collected 3023 urine spots between May 1996 and May 1998, at a rate of three to five samples per month, at any time of the day. The results show that circadian rhythmicity of UI in adults and children was found independent of the individual subject, age, gender, and season. Lowest UI levels were found between 8-11 h. A curve increasing progressively between 12 and 24 h was obtained. UI returned to base-line levels between 21 and 22 h in children only. UI peaks occurred 4-5 h after main meals; children's peaks occurred later than that of adults. Although the existence of a circadian rhythm of UI is probably universal, its profile, however, depends on alimentation. Because nadir of UI is represented by morning spots, this might seem an appropriate collecting period. In view of the significant circadian rhythmicity of UI, studies with restriction of sampling time to morning hours, for example, cannot be directly compared with studies in which urine is sampled all over the day.
135 citations
Journal Article•
TL;DR: Viscosity of whole blood increases in the morning in OSAS patients but not in healthy controls, which may be related to the increased susceptibility to cerebral ischemia in patients affected by OSAS, particularly evident in the early morning.
Abstract: Objective: Patients affected by obstructive sleep apnea syndrome (OSAS) have an increased risk of cardiovascular diseases such as stroke and myocardial infarction. The pathophysiological mechanisms leading to increased vascular risk are still matter of debate. A relative morning hyperviscosity could be one of the leading mechanisms of cardiovascular morbidity which is actually known to be especially high in the morning hours. Methods: Whole blood viscosity (WBV) at seven shear rates, ranging from 0.47 to 118 sec -1 , haematocrit (Hct), and plasma fibrinogen (F) concentration, were measured on venous blood samples in 12 patients with OSAS and in 8 healthy controls at 8-9 p.m. and at 7-8 a.m. the morning after. WBV values were normalized on Hct by the computation of the standardised normal deviate z on the normal database of the laboratory. Results: No changes were observed in controls. Hct, F and normalized WBV (independently from Hct changes) significantly increased in the morning hours in OSAS patients. Conclusions: Viscosity of whole blood increases in the morning in OSAS patients but not in healthy controls. This condition may be related to the increased susceptibility to cerebral ischemia in patients affected by OSAS, particularly evident in the early morning.
117 citations
TL;DR: Nighttime salivary cortisol sampling is a simple, accurate way to screen for hypercortisolism in children and rules out Cushing's syndrome in nearly all cases.
99 citations
TL;DR: If current diabetes diagnostic criteria are applied to patients seen in the afternoon, approximately half of all cases of undiagnosed diabetes in these patients will be missed.
Abstract: ContextCurrent diagnostic criteria for diabetes are based on plasma glucose
levels in blood samples obtained in the morning after an overnight fast, with
a value of 7.0 mmol/L (126 mg/dL) or more indicating diabetes. However, many
patients are seen by their physicians in the afternoon. Because plasma glucose
levels are higher in the morning, it is unclear whether these diagnostic criteria
can be applied to patients who are tested for diabetes in the afternoon.ObjectivesTo document diurnal variation in fasting plasma glucose levels in adults
not known to have diabetes, and to examine the applicability to afternoon-examined
patients of the current diagnostic criteria for diabetes.Design, Setting, and ParticipantsAnalysis of data from the US population–based Third National Health
and Nutrition Examination Survey (1988-1994) on participants aged 20 years
or older who had no previously diagnosed diabetes, who were randomly assigned
to morning (n = 6483) or afternoon (n = 6399) examinations, and who fasted
prior to blood sampling.Main Outcome MeasuresFasting plasma glucose levels in morning vs afternoon-examined participants;
diabetes diagnostic value for afternoon-examined participants.ResultsThe morning and afternoon groups did not differ in age, body mass index,
waist-to-hip ratio, physical activity index, glycosylated hemoglobin level,
and other factors. Mean (SD) fasting plasma glucose levels were higher in
the morning group (5.41 [0.01] mmol/L [97.4 {0.3} mg/dL]) than in the afternoon
group (5.12 [0.02] mmol/L [92.4 {0.4} mg/dL]; P<.001).
Consequently, prevalence of afternoon-examined participants with fasting plasma
glucose levels of 7.0 mmol/L (126 mg/dL) or greater was half that of participants
examined in the morning. The diagnostic fasting plasma glucose value for afternoon-examined
participants that resulted in the same prevalence of diabetes found in morning-examined
participants was 6.33 mmol/L (114 mg/dL) or greater.ConclusionsOur results indicate that if current diabetes diagnostic criteria are
applied to patients seen in the afternoon, approximately half of all cases
of undiagnosed diabetes in these patients will be missed.
96 citations
TL;DR: In healthy overnight fasted humans, neuroendocrine, autonomic nervous system, and metabolic counterregulatory responses are sensitive to the blunting effects of even short-duration prior hypoglycemia, which results in a hierarchy of blunted physiological responses with hypoglycemic symptom awareness less vulnerable than neuro endocrine responses.
Abstract: The aim of this study was to determine whether the duration of antecedent hypoglycemia regulates the magnitude of subsequent counterregulatory failure. A total of 31 lean healthy overnight-fasted individuals (16 men/15 women) were studied. There were 15 subjects (8 men/7 women) who underwent two separate 2-day randomized experiments separated by at least 2 months. On day 1, 2-h hyperinsulinemic (9 pmol x kg(-1) x min(-1)) euglycemic (5.2 +/- 0.1 mmol/l) or hypoglycemic (2.9 +/- 0.1 mmol/l) glucose clamps (prolonged hypoglycemia) were carried out in the morning and afternoon. Of the other subjects, 16 participated in a 2-day study in which day 1 consisted of morning and afternoon short-duration hypoglycemia experiments (hypoglycemic nadir of 2.9 +/- 0.1 mmol for 5 min), and 10 of these individuals underwent an additional 2-day study in which day 1 consisted of morning and afternoon intermediate-duration hypoglycemia (hypoglycemic nadir of 2.9 +/- 0.1 mmol for 30 min). The next morning (day 2) all subjects underwent an additional 2-h hyperinsulinemic-hypoglycemic clamp (2.9 +/- 0.1 mmol/l). The rate of fall of glucose (0.07 mmol/min) was carefully controlled during all hypoglycemic studies so that the glucose nadir was reached at 30 min. Despite equivalent day 2 plasma glucose and insulin levels, there were significant differences in counterregulatory physiological responses. Steady-state epinephrine, glucagon, growth hormone, cortisol, and pancreatic polypeptide levels were similarly significantly blunted (P < 0.01) by the differing duration day 1 hypoglycemia compared with day 1 euglycemia. Muscle sympathetic nerve activity and endogenous glucose production were also similarly blunted (P < 0.01) by day 1 hypoglycemia (relative to day 1 euglycemia). Day 2 hypoglycemic symptoms were significantly reduced (P < 0.01) after day 1 prolonged intermediate- but not short-duration hypoglycemia. In summary, two episodes of short-duration moderate hypoglycemia can produce significant blunting of key neuroendocrine and metabolic counterregulatory responses. Hypoglycemic symptom scores are reduced by prolonged but not short-duration prior hypoglycemia. We conclude that in healthy overnight fasted humans, 1) neuroendocrine, autonomic nervous system, and metabolic counterregulatory responses are sensitive to the blunting effects of even short-duration prior hypoglycemia, and 2) the duration of antecedent hypoglycemia results in a hierarchy of blunted physiological responses with hypoglycemic symptom awareness less vulnerable than neuroendocrine responses.
TL;DR: Levels of melatonin and of creatinine‐corrected 6‐OHMS in the first morning void urine are strongly correlated with total nocturnal plasma melatonin output and also with peakNocturnal melatonin values, indicating cost‐effective, widespread testing of the role played by melatonin in human health and disease.
Abstract: We evaluated the feasibility of using morning urine samples in epidemiological studies aimed at clarifying the relationship between nocturnal melatonin levels and breast cancer risk. Initially, a laboratory-based study of 29 women (40- 70 yr old) was performed to examine the correlation between plasma melatonin levels in hourly nocturnal blood samples and both melatonin and its major enzymatic metabolite, 6-hydroxymelatonin-sulfate (6-OHMS) in morning urine samples. In a companion field study, morning urine samples were collected from 203 healthy women to assess similarities and differences in laboratory versus field measures. Taken together, our results indicate: 1) levels of melatonin and of creatinine-corrected 6-OHMS in the first morning void urine are strongly correlated with total nocturnal plasma melatonin output (P < 0.001) and also with peak nocturnal melatonin values (P < 0.001); 2) similar ranges for 6-OHMS were found in the laboratory and the field; and 3) neither menopausal status nor hormonal replacement therapy altered 6-OHMS values in morning void urine. The inclusion of morning urine samples in epidemiological studies of cancer could allow cost-effective, widespread testing of the role played by melatonin in human health and disease.
TL;DR: Results indicate that among young women, acute strenuous resistance exercise of the nature used in this study is capable of producing modest but prolonged elevations of postexercise metabolic rate and possibly fat oxidation.
Abstract: This study determined the effect of an intense bout of resistive exercise on postexercise oxygen consumption, resting metabolic rate, and resting fat oxidation in young women (N=7, ages 22-35). On the morning of Day 1, resting metabolic rate (RMR) was measured by indirect calorimetry. At 13:00 hr, preexercise resting oxygen consumption was measured followed by 100 min of resistive exercise. Postexercise oxygen consumption was then measured for a 3-hr recovery period. On the following morning (Day 2), RMR was once again measured in a fasted state at 07:00. Postexercise oxygen consumption remained elevated during the entire 3-hr postexercise recovery period compared to the pre-exercise baseline. Resting metabolic rate was increased by 4.2% (p<.05) from Day 1 (morning prior to exercise: 1,419 +/- 58 kcal/24hr) compared to Day 2 (16 hr following exercise: 1,479 +/- kcal/24hr). Resting fat oxidation as determined by the respiratory exchange ratio was also significantly elevated on Day 2 compared to Day 1. These results indicate that among young women, acute strenuous resistance exercise of the nature used in this study is capable of producing modest but prolonged elevations of postexercise metabolic rate and possibly fat oxidation.
TL;DR: It is indicated that human circadian phase is dependent on the timing of darkness and/or sleep exposure and that strategies to treat circadian misalignment should consider not only the timing and intensity of light, but also the timing for sleep.
Abstract: To systematically determine the effects of daytime exposure to sleep in darkness on human circadian phase, four groups of subjects participated in 4-day studies involving either no nap (control), a morning nap (0900-1500), an afternoon nap (1400-2000), or an evening nap (1900-0100) in darkness. Except during the scheduled sleep/dark periods, subjects remained awake under constant conditions, i.e., constant dim light exposure (36 lx), recumbence, and caloric intake. Blood samples were collected at 20-min intervals for 64 h to determine the onsets of nocturnal melatonin and thyrotropin secretion as markers of circadian phase before and after stimulus exposure. Sleep was polygraphically recorded. Exposure to sleep and darkness in the morning resulted in phase delays, whereas exposure in the evening resulted in phase advances relative to controls. Afternoon naps did not change circadian phase. These findings indicate that human circadian phase is dependent on the timing of darkness and/or sleep exposure and that strategies to treat circadian misalignment should consider not only the timing and intensity of light, but also the timing of darkness and/or sleep.
TL;DR: It is concluded that the bacterioplankton in the euphotic layer of the subtropical Atlantic are not limited by the availability of N+P in the morning but at noon when they are competing with phytoplankon for the inorganic N+ P sources.
Abstract: We tested the hypothesis that in the euphotic zone of oligotrophic oceanic waters, the growth-limiting nutrients for bacterioplankton vary over a diel cycle due to competition with phyto- plankton, leading to distinct diel patterns in bacterioplankton. During a cruise across the subtropical Atlantic Ocean, a distinct diel periodicity in bacterioplankton was detectable, with highest bacterial abundance in the early morning and declining over the day. A peak in the frequency of dividing cells (FDC, 20 to 25% of the total bacterial community) was recorded at midnight; FDC rates were consis- tently low during the day and cell volume increased over the day until the early night period. No diel variations in these parameters were detectable in the layers below the deep chlorophyll maximum (DCM). Bio-assay experiments with freshly collected, N+P amended water were started in the early morning. No significant bacterial growth was detectable in the early morning while, in the bio-assays that started at noon, significant bacterial growth was detectable in the N+P treatments. P amendment alone also caused an increase in bacterial abundance although to a lesser extent. Thus, we have evi- dence that the bacterioplankton in the euphotic layer of the subtropical Atlantic are not limited by the availability of N+P in the morning (most likely limited in C) but at noon when they are competing with phytoplankton for the inorganic N+P sources. Based on the concomitantly measured decline in inorganic N+P in the bio-assays, we estimated the C:N:P ratio of newly produced bacteria. The mean atomic C:N:P ratio for the bacteria in the N+P amended bio-assay experiments started in the early morning was C:N:P = 15:13:1 while the corresponding ratio for bacteria in the bio-assays started at noon was C:N:P = 118:11:1. This diel variation in the C:N:P ratio was caused by the 1 order of mag- nitude higher bacterial C production at noon as compared to the early morning. Thus, excess uptake of N+P occurs during the morning and luxury C uptake during noon. This plasticity in the C:N:P ratio of bacterioplankton might be a strategy to overcome, at least partly, periods of shortage in a specific nutrient species in the oligotrophic subtropical Atlantic.
TL;DR: The platelet peak appears to coincide with late afternoon peak frequencies of sudden cardiac death and fatal stroke, and the data suggest that proper timing of single samples may improve the usefulness and accuracy of diagnosis, risk assessment, and therapy.
TL;DR: A systematic review of the published literature on morning report was done in order to identify the various purposes and modalities of morning report, to find evidence in support of its educational value, and to discuss possible future directions for research onMorning report.
Abstract: Residents rank morning report as the most important educational activity of their residency training. Although there is a lack of documented evidence as to the educational value of morning report, the practice is ubiquitous across almost all primary care residency programs in North America. The ever-changing practice of medicine and ongoing demands for evidence in medical education force us to examine essential aspects of morning report in order to base future decisions about morning report on sound educational evidence. Thus, a systematic review of the published literature on morning report was done in order to identify the various purposes and modalities of morning report, to find evidence in support of its educational value, and to discuss possible future directions for research on morning report. The term ‘‘morning report’’ is used to describe case-based conferences where residents, attending physicians, and others meet to present and discuss clinical cases. The term includes resident reports, morning or housestaff conferences, and morning sessions but excludes work rounds or teaching rounds. In a typical morning report, the team on duty during the night presents recently admitted patients, followed by a general discussion of the cases and related topics.
TL;DR: The body's ability to remove a heat load is less in the early morning, when the circadian system is in a “heat gain” mode, than in the late afternoon, when heat gain and “ heat loss” modes are balanced more evenly.
Abstract: Twelve healthy male subjects each undertook two bouts of moderate exercise (70% VO2max for 30 minutes) in the morning (08:00) and late afternoon (18:00) at least 4 days apart Measurements were made of heart rate, core (rectal) temperature, sternum skin temperature, and forearm skin blood flow during baseline conditions, during the bout of exercise, and throughout a 30-minute recovery period Comparisons were made of the changes of heart rate, temperature, and skin blood flow produced by the exercise at the two times of day Student t tests indicated that baseline values for core temperature (3715 degrees C +/- 006 degrees C vs 3677 degrees C +/- 006 degrees C) and sternum temperature (3360 degrees C +/- 029 degrees C vs 3270 degrees C + 038 degrees C) were significantly (p < 05) higher in the late afternoon than the early morning Two-way analysis of variance (ANOVA) indicated that the increases in core and sternum temperatures during exercise were significantly less (p = 0039 and 0421, respectively) during the afternoon bout of exercise compared with the morning, even though the work loads, as determined by changes in heart rate, were not significantly different (p = 798) at the two times of testing There were also tendencies for resting forearm skin blood flow to be higher in the afternoon than in the morning and for exercise to produce a more rapid rise in this variable in the afternoon The possible mechanisms producing these responses to exercise are discussed in terms of those that are responsible for the normal circadian rhythm of core temperature It is concluded that the body's ability to remove a heat load is less in the early morning, when the circadian system is in a "heat gain" mode, than in the late afternoon, when heat gain and "heat loss" modes are balanced more evenly
TL;DR: The findings in this study suggest that repeated saliva sampling and seasonal variation in cortisol levels may independently affect adrenal response and, therefore, need to be accounted for in longitudinal studies.
Abstract: Assessments of cortisol levels in saliva have been widely used by both researchers and clinicians as an index of adrenal functioning. Quarterly measurements of morning and evening cortisol levels were determined in a longitudinal study of 147 participants (72 women and 75 men) followed for I year each. The analysis of salivary cortisol revealed no significant gender or age differences in the sample. There was a sequence effect in quarterly cortisol values with a progressive decrease in serial measurements, especially notable in the morning values, as well as a seasonal variation in cortisol levels with significantly higher levels found in winter and fall, compared with spring and summer. The findings in this study suggest that repeated saliva sampling and seasonal variation in cortisol levels may independently affect adrenal response and, therefore, need to be accounted for in longitudinal studies.
TL;DR: The overall results of this study do not support the melatonin hypothesis, but there is some suggestion of a possible cumulative effect of magnetic field exposure on the stability of individual melatonin measurements over time.
Abstract: Magnetic field-induced suppression of nocturnal melatonin in humans has been reported in occupational and residential studies, but not in laboratory-based exposure studies. The present study examined whether this contrasting pattern of results might be related to associated differences in exposure duration or to field-induced measurement instability over time. Thirty healthy young men were evaluated using a randomized, double-blind test protocol. Statistical analysis indicated that 4 consecutive nights of exposure to power-frequency magnetic fields at occupational intensity (resultant flux density = 28.3 microtesla, muT, [283 milligauss, mG]) had no differential effect on concentrations of melatonin or its major enzymatic metabolite (6-hydroxymelatonin sulfate, 6-OHMS) in daily morning urine samples, compared to equivalent no-exposure sham control conditions. The consistency of intra-individual urinary measurements over the 4 test nights also was quite high (P < 0.01) in the sham control condition. In contrast, repeated nightly exposure to the magnetic field was associated with reduced consistency. Morning urinary measures obtained after exposure on night 4 differed (P < 0.01) from similar measures obtained after the second and third exposure night. Thus, while the overall results of this study do not support the melatonin hypothesis, there is some suggestion of a possible cumulative effect of magnetic field exposure on the stability of individual melatonin measurements over time. Additional research with longer periods of controlled exposure may be warranted.
TL;DR: In this article, the effect of starting and stopping terbutaline treatment on morning and evening peak flows was investigated in a randomized four-way, double-dummy, cross-over comparison of inhaled terbutalin and budesonide, combined treatment and matching placebo.
TL;DR: There was a positive correlation between foliage weight and production of volatile chemicals that was strongly evident in mature potato plants, and much less evident in young plants during morning and afternoon, and the factors affecting the volatile emissions of intact potato plants are discussed.
Abstract: The quantity, ratios, diurnal rhythm, and correlation with foliage weight of volatile chemicals emitted by young and mature intact potato plants were determined during the fourth (morning), eighth (noon) and fourteenth (afternoon) hour of the photophase. The major compounds released by young and mature intact potato plants, Solanum tuberosum, during the photophase, were the sesquiterpene hydrocarbons β-caryophyllene, (E)-β-farnesene, (Z,Z)-α-farnesene, germacrene-D, β-bisabolene, and an unknown compound A. The quantity of the major volatile chemicals emitted was subject to diurnal rhythm. In young potatoes, all major compounds except unknown A showed a steady increase during the photophase, with afternoon production significantly higher than that in the morning. In mature potatoes, all compounds, including unknown A, were significantly higher during the afternoon when compared to morning. Although the variability in quantity of volatile chemicals released between individual plants was very high, the ratios were stable between the sets of replicates. The correlation of foliage weight and emission of the volatile compounds was affected by the developmental stage of the plant and the time of the day. There was a positive correlation between foliage weight and production of volatile chemicals that was strongly evident in mature potato plants, and much less evident in young plants during morning and afternoon. No positive correlation between foliage weight and production of volatile chemicals was observed during noon for either age tested. The factors affecting the volatile emissions of intact potato plants are discussed.
TL;DR: In general, use of evening milkings less accurately estimated yields than did use of morning milkings, and among the three yield traits the lowest accuracy of estimation of daily yield was found for fat yield.
TL;DR: It is concluded from the data that there is a clear free cortisol response to awakening for both nocturnal and morning awakening although the absolute levels produced are lower forNocturnal awakening when basal cortisol is low.
Abstract: Free cortisol as measured in saliva increased markedly following awakening. This study investigated, with 11 adults (mean age 21.7 yrs) whether the awakening cortisol response can be generated in the middle of nocturnal sleep. In a within subject design, salivary cortisol response was measured under three different awakening conditions: at normal morning awakening time; awakening 4 hrs prior to normal awakening time; and awakening the following morning after interrupted sleep. The overall main effect was a linear increase in free cortisol following awakening with no significant interaction with awakening condition. Cortisol levels differed by awakening condition. The two morning awakening conditions were comparable but values were lower for night awakening. It is concluded from the data that there is a clear free cortisol response to awakening for both nocturnal and morning awakening although the absolute levels produced are lower for nocturnal awakening when basal cortisol is low. Nocturnal interruption of sleep did not affect the subsequent morning response.
TL;DR: In this paper, the authors conducted a study assessing the relationship between Morningness-Eveningness, time-of-day, and performance on the Multidimensional Aptitude Battery IQ (MAB-IQ) and Inspection Time (IT) tasks.
TL;DR: Results show that a single dose of sibutramine in lean humans induces a potent reduction in intake, and that its action is modulated according to the time of occurrence and the structure of the meal.
TL;DR: Once-daily treatment with fluticasone propionate was well tolerated and demonstrated some dose-related trends in improvements in lung function and asthma control in patients with moderate asthma.
TL;DR: Treated black and Hispanic hypertensives are less likely to "dip" than non-Hispanic whites, and of the 10 most commonly prescribed antihypertensives, no single drug was positively associated with nocturnal BP decline.
TL;DR: Results from the two-oscillator model of circadian rhythmicity are interpreted, indicating that two mutually coupled oscillators (evening and morning) differing in their entrainability may participate in measuring of the dark-phase duration.
TL;DR: It is hypothesized that morning bright light in demented patients reduces the agitation rating and directly observed disruptive behavior, but increases observed positive behavior.
Abstract: The objective of this study was to examine the effects of morning bright light on behavioral disturbances in dementia using a repeated measures ABA design. We hypothesized that morning bright light in demented patients reduces the agitation rating and directly observed disruptive behavior, but increases observed positive behavior.The study was done in a special care unit of a long term care facility, with 16 demented residents ages 60 to 89, 13 female and three male. Morning bright light (Day-Light Box 10000, produced by DayLight Technologies, Inc, providing 10,000 lux) was administered Monday to Friday during the treatment week. The Global Deterioration Scale rating at baseline, followed by baseline, treatment and post-treatment ratings in the Cohen-Mansfield Agitation Inventory (CMAI) and Environment-Behavior Interaction Code (EBIC) were used as measurementsCompared to baseline, the mean total Cohen-Mansfield score decreased more during the phototherapy week than during the post-treatment week (p < 0.05...