Showing papers on "Morning published in 2017"

Comparison of Insulin Glargine 300 Units/mL and 100 Units/mL in Adults With Type 1 Diabetes: Continuous Glucose Monitoring Profiles and Variability Using Morning or Evening Injections.

Abstract: OBJECTIVE The objective of this study was to compare glucose control in participants with type 1 diabetes receiving insulin glargine 300 units/mL (Gla-300) or glargine 100 units/mL (Gla-100) in the morning or evening, in combination with mealtime insulin. RESEARCH DESIGN AND METHODS In this 16-week, exploratory, open-label, parallel-group, two-period crossover study (clinicaltrials.gov identifier NCT01658579), 59 adults with type 1 diabetes were randomized (1:1:1:1) to once-daily Gla-300 or Gla-100 given in the morning or evening (with crossover in the injection schedule). The primary efficacy end point was the mean percentage of time in the target glucose range (80–140 mg/dL), as measured using continuous glucose monitoring (CGM), during the last 2 weeks of each 8-week period. Additional end points included other CGM glycemic control parameters, hypoglycemia (per self-monitored plasma glucose [SMPG]), and adverse events. RESULTS The percentage of time within the target glucose range was comparable between the Gla-300 and Gla-100 groups. There was significantly less increase in CGM-based glucose during the last 4 h of the 24-h injection interval for Gla-300 compared with Gla-100 (least squares mean difference −14.7 mg/dL [95% CI −26.9 to −2.5]; P = 0.0192). Mean 24-h glucose curves for the Gla-300 group were smoother (lower glycemic excursions), irrespective of morning or evening injection. Four metrics of intrasubject interstitial glucose variability showed no difference between Gla-300 and Gla-100. Nocturnal confirmed ( CONCLUSIONS Less increase in CGM-based glucose levels in the last 4 h of the 24-h injection interval, smoother average 24-h glucose profiles irrespective of injection time, and reduced nocturnal hypoglycemia were observed with Gla-300 versus Gla-100.

Chronotype differences in timing of energy and macronutrient intakes: A population-based study in adults.

Abstract: Objective To examine the association between chronotype and timing of energy and macronutrient intakes in adults. Methods The study sample included 1,854 participants from the National FINRISK 2007 and FINDIET 2007 studies, aged 25 to 74 years. Diet was assessed with 48-hour dietary recalls. Chronotype was assessed with a shortened version of Horne and Ostberg's Morningness–eveningness Questionnaire. Associations between chronotype and intakes of energy and macronutrients in the morning (by 10 am) and in the evening (after 8 pm) were analyzed with linear regression and ANOVA followed by Bonferroni post hoc test. Results In the morning, evening types had lower energy and macronutrient intakes (except for sucrose of which they had a higher intake) than morning types (P < 0.05), while in the evening, evening types had higher intakes of energy, sucrose, fat, and saturated fatty acids than morning types (P < 0.05). On the weekend, chronotype differences in evening intakes of energy, sucrose, and fat intake were more pronounced, and evening types had more eating occasions and more irregular meal times than morning types. Conclusions Postponed energy and macronutrient intake timing of evening types with unfavorable dietary patterns may put them at higher risk of obesity and metabolic disturbances in the future.

The Efficacy of Proton Pump Inhibitors for the Treatment of Asthma in Adults

Abstract: Methods: A literature search was undertaken using MEDLINE (1950-January 2010), PubMed (1950January 2010), EMBASE (1980-January 2010), and Cochrane Central Register of Controlled Trials (through January 31, 2010). Randomized, placebo-controlled trials evaluating the efficacy of PPIs for treatment of asthma in adults were selected. The primary outcome of interest was morning peak expiratory flow (PEF) rate. Secondary outcomes included objective (evening PEF rate and forced expiratory volume in 1 second) and subjective (asthma symptoms score and Asthma Quality of Life Questionnaire score) measures. Influence of study characteristics on outcomes was examined by subgroup analyses and meta-regression. Results: Eleven trials (2524 patients) met inclusion criteria. Overall, patients had a higher mean morning PEF rate after treatmentwithPPIscomparedwithplacebo(meandifference,8.68L/min[95%confidence interval,2.35-15.02]). No significant single large-study effect, temporal effect, or publicationbiaswasseen.Subgroupanalysisrevealedatrend toward a larger improvement in morning PEF rate in studiesenrollingonlypatientswithgastroesophageal refluxdisease (mean difference,16.90 L/min [95% confidence interval,0.85-32.95]).Analysesof secondaryoutcomes(asthma symptomsscore,AsthmaQualityofLifeQuestionnairescore, eveningPEFrate,andforcedexpiratoryvolumein1second) showednosignificantdifferencebetweenPPIsandplacebo.

Eating your feelings? Testing a model of employees' work-related stressors, sleep quality, and unhealthy eating

Abstract: Although organizational research on health-related behaviors has become increasingly popular, little attention has been paid to unhealthy eating. Drawing on the self-regulation perspective, we conducted 2 daily diary studies to examine the relationships between work-related stressors, sleep quality, negative mood, and eating behaviors. Study 1 sampled 125 participants from 5 Chinese information technology companies and showed that when participants experienced higher levels of job demands in the morning, they consumed more types of unhealthy food and fewer types of healthy food in the evening. In addition, sleep quality from the previous night buffered the effect of morning job demands on evening unhealthy food consumption. Study 2 used data from 110 customer service employees from a Chinese telecommunications company and further demonstrated a positive association between morning customer mistreatment and evening overeating behaviors, as well as the buffering effect of sleep quality. Results from Study 2 also supported afternoon negative mood as a mediator linking morning customer mistreatment to evening overeating behaviors. Finally, our findings revealed that the buffering effect of sleep quality was channeled through employees' vigor in the morning, which subsequently weakened the effect of customer mistreatment on negative mood. (PsycINFO Database Record

Annual variation in daily light exposure and circadian change of melatonin and cortisol concentrations at a northern latitude with large seasonal differences in photoperiod length.

Abstract: Seasonal variations in physiology and behavior have frequently been reported. Light is the major zeitgeber for synchronizing internal circadian rhythms with the external solar day. Non-image forming effects of light radiation, for example, phase resetting of the circadian rhythms, melatonin suppression, and acute alerting effects, depend on several characteristics of the light exposure including intensity, timing and duration, spectral composition and previous light exposure, or light history. The aim of the present study was to report on the natural pattern of diurnal and seasonal light exposure and to examine seasonal variations in the circadian change of melatonin and cortisol concentrations for a group of Swedish office workers. Fifteen subjects participated in a field study that was carried out in the south of Sweden. Ambulatory equipment was used for monthly measurements of the daily exposure to light radiation across the year. The measurements included illuminance and irradiance. The subjects collected saliva samples every 4 h during 1 day of the monthly measuring period. The results showed that there were large seasonal differences in daily amount of light exposure across the year. Seasonal differences were observed during the time periods 04:00–08:00, 08:00–12:00, 12:00–16:00, 16:00–20:00, and 20:00–24:00. Moreover, there were seasonal differences regarding the exposure pattern. The subjects were to a larger extent exposed to light in the afternoon/evening in the summer. During the winter, spring, and autumn, the subjects received much of the daily light exposure in the morning and early afternoon. Regarding melatonin, a seasonal variation was observed with a larger peak level during the winter and higher levels in the morning at 07:00. This study adds to the results from other naturalistic studies by reporting on the diurnal and seasonal light exposure patterns for a group living at a northern latitude of 56° N, with large annual variations in photoperiod length. It seems to be seasonal variation in the lighting conditions, both concerning intensities as well as regarding the pattern of the light exposure to which people living at high latitudes are exposed which may result in seasonal variation in the circadian profile of melatonin.

Variation of Human Milk Glucocorticoids over 24 hour Period

Abstract: Human milk (HM) contains a complex array of hormones, including members of the glucocorticoid family. The predominant glucocorticoids, cortisol and cortisone may influence the growth and behaviour of the breastfed infant. However, little is understood of the factors regulating the levels of these hormones within HM. The aim of the study was to examine HM cortisol and cortisone concentration, measured in samples collected at each feed during a 24 hour period. Twenty three exclusively breastfeeding mothers collected milk, prior to and after each breastfeeding session over 24 hour period at 3.2(1.60) months. HM cortisol and cortisone levels were measured using high pressure liquid chromatography mass spectroscopy. Cortisone was the predominant glucocorticoid (3.40 ng/ml), and cortisol was detected in all samples (1.62 ng/ml). A positive correlation was found between cortisone and cortisol (r = 0.61, y = 1.93 ± 0.24, p < 0.0001). Cortisol and cortisone concentrations were significantly higher in feeds in the morning (2.97 ng/ml and 4.88 ng/ml), compared to afternoon (1.20 ng/ml and 3.54 ng/ml), evening (0.69 ng/ml and 2.13 ng/ml) and night (1.59 and 3.27 ng/ml). No difference was found between glucocorticoids level of the milk expressed for collection either before or immediately after the breastfeed, or between milk collected from the left or right breast. This study shows that HM glucocorticoid concentrations exhibit a 24 hour pattern, with highest peak levels in the early morning, reflecting the circadian pattern as previously reported in plasma. Thus, HM glucocorticoid concentrations are likely to reflect those in the maternal circulation.

Circadian rhythm effect on physical tennis performance in trained male players

Abstract: To determine the effect of circadian rhythm on neuromuscular responses and kinematics related to physical tennis performance, after a standardised warm-up, 13 highly competitive male tennis players were tested twice for serve velocity/accuracy (SVA), countermovement vertical jump (CMJ), isometric handgrip strength (IS), agility T-test (AGIL) and a 10-m sprint (10-m RUN). In a randomised, counter-balance order, tennis players underwent the test battery twice, either in the morning (i.e., AM; 9:00 h) and in the afternoon (i.e., PM; 16:30 h). Paired t-tests were used to analyse differences due to time-of-day in performance variables. Comparison of morning versus afternoon testing revealed that SVA (168.5 ± 6.5 vs. 175.2 ± 6.1 km · h−1; P = 0.003; effect size [ES] = 1.07), CMJ (32.2 ± 0.9 vs. 33.7 ± 1.1 cm; P = 0.018; ES = 1.46), AGIL (10.14 ± 0.1 vs. 9.91 ± 0.2 s; P = 0.007; ES = 1.23) and 10-m RUN time (1.74 ± 0.1 vs. 1.69 ± 0.1 s; P = 0.021; ES = 0.67) were significantly blunted during the morning ...

Fine Particulate Constituents and Lung Dysfunction: A Time-Series Panel Study.

Abstract: The evidence is quite limited regarding the constituents of fine particulate matter (PM2.5) responsible for lung dysfunction. We designed a time-series panel study in 28 patients to examine the effects of 10 major constituents of PM2.5 on lung function with repeated daily measurements from December 2012 to May 2013 in Shanghai, China. We applied a linear mixed-effect model combined with a distributed lag model to estimate the cumulative effects of PM2.5 constituents on morning/evening forced expiratory volume in 1-s (FEV1) and peak expiratory flow (PEF) over a week. The cumulative decreases in morning FEV1, evening FEV1, morning PEF and evening PEF associated with an interquartile range (35.8 μg/m3) increase in PM2.5 concentrations were 33.49 [95% confidence interval(CI):2.45,54.53] mL, 16.80 (95%CI:3.75,29.86) mL, 4.48 (95%CI:2.30,6.66) L/min, and 1.31 (95%CI:-0.85,3.47) L/min, respectively. These results were not substantially changed after adjusting for gases in two-pollutant models. The associations o...

Chronotype Differences in Timing of Energy and Macronutrient Intakes: A Population-Based Study in Adults

Abstract: Objective To examine the association between chronotype and timing of energy and macronutrient intakes in adults. Methods The study sample included 1,854 participants from the National FINRISK 2007 and FINDIET 2007 studies, aged 25 to 74 years. Diet was assessed with 48-hour dietary recalls. Chronotype was assessed with a shortened version of Horne and Ostberg's Morningness–eveningness Questionnaire. Associations between chronotype and intakes of energy and macronutrients in the morning (by 10 am) and in the evening (after 8 pm) were analyzed with linear regression and ANOVA followed by Bonferroni post hoc test. Results In the morning, evening types had lower energy and macronutrient intakes (except for sucrose of which they had a higher intake) than morning types (P < 0.05), while in the evening, evening types had higher intakes of energy, sucrose, fat, and saturated fatty acids than morning types (P < 0.05). On the weekend, chronotype differences in evening intakes of energy, sucrose, and fat intake were more pronounced, and evening types had more eating occasions and more irregular meal times than morning types. Conclusions Postponed energy and macronutrient intake timing of evening types with unfavorable dietary patterns may put them at higher risk of obesity and metabolic disturbances in the future.

Stress in School. Some Empirical Hints on the Circadian Cortisol Rhythm of Children in Outdoor and Indoor Classes

Abstract: This prospective longitudinal survey compared the stress levels of students taught using an outdoor curriculum in a forest, with children in a normal school setting. We were especially interested in the effect outdoor teaching might have on the children’s normal diurnal cortisol rhythm. 48 children (mean age = 11.23; standard deviation (SD) = 0.46) were enrolled, with 37 in the intervention group (IG), and 11 in the control group (CG). The intervention consisted of one full school day per week in the forest over the school year. Stress levels were measured in cortisol with three samples of saliva per day. Furthermore, the data allowed for statistical control of physical activity (PA) values. For data analysis, we used a linear mixed-effects model (LMM) with random intercept and general correlation matrix for the within-unit residuals. The LMM yields that IG have expected greater decline of cortisol compared to CG; rate 0.069 µg/L vs. 0.0102 µg/L (log-units/2 h), p = 0.009. PA does not show a statistically significant interaction with cortisol (p = 0.857), despite being higher in the intervention group (p < 0.001). The main effect in our measures was that the IG had a steady decline of cortisol during the school day. This is in accordance with a healthy child’s diurnal rhythm, with a significant decline of cortisol from morning to noon. This effect is constant over the school year. The CG does not show this decline during either measurement day. Further research is needed to fully explain this interesting phenomenon.

Do associations between objectively-assessed physical activity and neighbourhood environment attributes vary by time of the day and day of the week? IPEN adult study

Abstract: To more accurately quantify the potential impact of the neighbourhood environment on adults’ physical activity (PA), it is important to compare environment-PA associations between periods of the day or week when adults are more versus less likely to be in their neighbourhood and utilise its PA resources. We examined whether, among adults from 10 countries, associations between objectively-assessed neighbourhood environment attributes and moderate-to-vigorous physical activity (MVPA) varied by time of the day and day of the week. The secondary aim was to examine whether such associations varied by employment status, gender and city. This cross-sectional study included 6,712 adults from 14 cities across 10 countries with ≥1 day of valid accelerometer-assessed MVPA and complete information on socio-demographic and objectively-assessed environmental characteristics within 0.5 and 1 km street-network buffers around the home. Accelerometer measures (MVPA min/h) were created for six time periods from early morning until late evening/night, for weekdays and weekend days separately. Associations were estimated using generalized additive mixed models. Time of the day, day of week, gender and employment status were significant moderators of environment-MVPA associations. Land use mix was positively associated with MVPA in women who were employed and in men irrespective of their employment status. The positive associations between MVPA and net residential density, intersection density and land use mix were stronger in the mornings of weekdays and the afternoon/evening periods of both weekdays and weekend days. Associations between number of parks and MVPA were stronger in the mornings and afternoon/evenings irrespective of day of the week. Public transport density showed consistent positive associations with MVPA during weekends, while stronger effects on weekdays were observed in the morning and early evenings. This study suggests that space and time constraints in adults’ daily activities are important factors that determine the impact of neighbourhood attributes on PA. Consideration of time-specific associations is important to better characterise the magnitude of the effects of the neighbourhood environment on PA. Future research will need to examine the contribution of built environment characteristics of areas surrounding other types of daily life centres (e.g., workplaces) to explaining adults’ PA at specific times of the day.

Salivary cortisol concentration after high-intensity interval exercise: Time of day and chronotype effect

Abstract: Due to personal and working necessities, the time for exercise is often short, and scheduled early in the morning or late in the afternoon. Cortisol plays a central role in the physiological and behavioral response to a physical challenge and can be considered as an index of exercise stress. Therefore, the aim of this study was to evaluate the influence of the circadian phenotype classification on salivary cortisol concentration in relation to an acute session of high-intensity interval exercise (HIIE) performed at different times of the day. Based on the morningness-eveningness questionnaire, 12 M-types (N = 12; age 21 ± 2 years; height 179 ± 5 cm; body mass 74 ± 12 kg, weekly training volume 8 ± 1 hours) and 11 E-types (N = 11; age 21 ± 2 years; height 181 ± 11 cm; body mass 76 ± 11 kg, weekly training volume 7 ± 2 hours) were enrolled in a randomized crossover study. All subjects underwent measurements of salivary cortisol secretion before (PRE), immediately after (POST), and 15 min (+15 min), 30 min (+30 min), 45 min (+45 min) and 60 min (+60 min) after the completion of both morning (08.00 am) and evening (08.00 p.m.) high-intensity interval exercise. Two-way analysis of variance with Tuckey's multiple comparisons test showed significant increments over PRE-cortisol concentrations in POSTcondition both in the morning (4.88 ± 1.19 ng · mL-1 vs 6.60 ± 1.86 ng · mL-1, +26.1%, P 0.8) and in the evening (1.56 ± 0.48 ng · mL-1 vs 2.34 ± 0.37, +33.4%, P = 0.034, d > 0.6) exercise in all the 23 subject that performed the morning and the evening HIIE. In addition, during morning exercise, significant differences in cortisol concentration between M-types and E-types at POST (5.49 ± 0.98 ng · mL-1 versus 8.44 ± 1.08 ng · mL-1, +35%, P 0.8), +15 min (4.52 ± 0.42 ng · mL-1 versus 6.61 ± 0.62 ng · mL-1, +31.6%, P 0.8), +30 min (4.10 ± 1.44 ng · mL-1 versus 6.21 ± 1.60 ng · mL-1, +34.0%, P < 0.0001, d = 0.7), + 45 min (3.78 ± 0.55 ng · mL-1 versus 5.80 ± 0.72 ng · mL-1, +34.9%, P < 0.0001, d = 0.7), and + 60 min condition(3.53 ± 0.45 ng · mL-1 versus 5.78 ± 1.13 ng · mL-1, 38.9%, P = 0.0008, d = 0.7) were noted. No statistical significant differences between M-types and E-types during evening HIIE on post-exercise cortisol concentration were detected. E-types showed a higher morning peak of salivary cortisol respect to M-types when performing a HIIE early in the morning and produced higher salivary cortisol concentrations after the cessation of the exercise. Practical applications suggest that it is increasingly important for the exercise professionals to identify the compatibility between time of day for exercising and chronotype to find the individual's favorable circadian time to perform a HIIE.

Chronotype, class times, and academic achievement of university students.

Abstract: Numerous studies over the years have documented an effect of human chronotypes on physiological and psychological processes. Studies evaluating the impact of an individual's chronotype on his/her academic achievement have indicated that morning chronotypes have an academic advantage over evening chronotypes. However, these studies did not account for the time of day in which the participants were being evaluated. The goal of the present study was to examine whether morning chronotypes do have an academic advantage over evening chronotypes when the time of day of classes and exams is taken into consideration. We obtained morningness-eveningness scores and course grades from 207 university students who took classes (and exams) at different times of the day. We confirmed that morning chronotypes attain better grades than evening chronotypes, although the association is weak (r2 = 0.02). The difference persisted even after the time of day of classes and exams was taken into consideration. This is probably due to the fact that evening chronotypes are generally more sleep deprived than morning chronotypes as a result of the early schedule of most schools, which can impair their performance both early and late in the day.

Daily rhythmicity of the thermoregulatory responses of locally adapted Brazilian sheep in a semiarid environment

Abstract: The goal of this study was to evaluate the daily rhythmicity of the thermoregulatory responses of Morada Nova ewes that were raised in a semiarid environment. The experiment was conducted during the dry season. Data were collected from 5:00 a.m. to 4:00 a.m.. Samples were taken over the course of 8 days, with a 1-week interval between sampling periods. During each day that the data were collected, animals were measured once an hour for 24 h in an area directly exposed to solar radiation. The environment was characterized by measuring the following variables: air temperature (TA), relative humidity (RH), Black Globe Humidity Index (BGHI), radiant heat load (RHL), and wind speed (WS). Physiological variables that were measured included rectal temperature (RT, °C), respiratory rate (RR, breaths/min), surface temperature (ST, °C), and sweating rate (SR, g m2 h−1). We observed that RT, RR, and ST increased as environmental conditions became more stressful. Specifically, environmental conditions became more stressful as RHL, air temperature, and BGHI increased, while RH decreased. All physiological variables of the animals were strongly affected by the time of the day: environmental variables changed drastically between nighttime and noon. Physiological parameters increased sharply from the morning (7:00 a.m.–10:00 a.m.) until noon (11:00 a.m.–2:00 p.m.), except for sweating rate. After noon, these variables began to drop until nighttime (11:00 p.m.–6:00 am), and values of the main physiological indexes were stable during this period. The Morada Nova breed exhibited daily cyclic variations in thermoregulatory responses. Evaporative heat loss mechanisms were triggered during the most stressful times of the day. The first mechanism that animals used was panting, which was an immediate response to environmental heat stress. Cutaneous evaporation had a slower response mechanism to environmental heat stress. Homeothermy conditions were restored to the animals at approximately 5:00 p.m.; however, these findings confirm the importance of providing environmental protection during critical periods of the day, even for locally adapted breeds. These responses suggest that the use of thermal storage allowed the animals to achieve equilibrium with the environment and maintain a stable body temperature.

Seasonal and time-of-day variations in acute non-image forming effects of illuminance level on performance, physiology, and subjective well-being.

Abstract: This study investigated seasonal and time-of-day dependent moderations in the strength and direction of acute diurnal non-image forming (NIF) effects of illuminance level on performance, physiology, and subjective well-being. Even though there are indications for temporal variations in NIF-responsiveness to bright light, scientific insights into potential moderations by season are scarce. We employed a 2 (Light: 165 versus 1700 lx at the eye level, within) × 2 (Season: autumn/winter versus spring, between) × 2 (Time of day: morning versus afternoon, between) mixed-model design. During each of the two 90-min experimental sessions, participants (autumn/winter: N = 34; spring: N = 39) completed four measurement blocks (incl. one baseline block of 120 lx at the eye level) each consisting of a Psychomotor Vigilance Task (PVT) and a Backwards Digit-Span Task (BDST) including easy trials (4-6 digits) and difficult trials (7-8 digits). Heart rate (HR) and skin conductance level (SCL) were measured continuously. At the end of each lighting condition, subjective sleepiness, vitality, and mood were measured. The results revealed a clear indication for significant Light * Season interaction effects on both subjective sleepiness and vitality, which appeared only during the morning sessions. Participants felt significantly more vital and less sleepy in winter, but not in spring during bright light exposure in the morning. In line with these subjective parameters, participants also showed significantly better PVT performance in the morning in autumn/winter, but not in spring upon bright light exposure. Surprisingly, for difficult working memory performance, the opposite was found, namely worse performance during bright light exposure in winter, but better performance when exposed to bright light in spring. The effects of bright versus regular light exposure on physiology were quite subtle and largely nonsignificant. Overall, it can be concluded that acute illuminance-induced NIF effects on subjective alertness and vitality as well as objectively measured vigilance in the morning are significantly moderated by season. Possibly, these greater illuminance-induced benefits during the morning sessions in autumn/winter compared to spring occurred due to increased responsiveness to bright light exposure as a function of a relatively low prior light dose in autumn/winter.

Effect of Time-of-Day on Biochemical Markers in Response to Physical Exercise

Abstract: Ammar, A, Chtourou, H, and Souissi, N. Effect of time-of-day on biochemical markers in response to physical exercise. J Strength Cond Res 31(1): 272-282, 2017-It is well established that many physiological functions are time-of-day (TOD) dependent, and their circadian rhythms are well documented in healthy populations at resting state. In fact, greater rate of oxidative stress, white blood cell, homocysteine, and muscle damage markers were shown in the early evening (≈18:00 hours), and more efficient antioxidant activity was observed in the early morning (≈06:00 hours). During physical tasks, the majority of the above-mentioned physiological functions increase from pre to post physical exercise with different rates of increases from morning to evening. These different rates of increases are suggested to alter the physiological resting diurnal variation. In this context, given the possible significant interaction "TOD × physical exercise," circadian rhythms of the physiological responses during physical activity are still not well established in trained subjects. Otherwise, it was suggested that the diurnal variation of these biochemical parameters could, in part, explain the typical diurnal fluctuation of physical performance. Therefore, the aim of this review was to summarize the currently available studies investigating the circadian rhythms of physiological functions at rest and after physical exercise and to establish their possible effect on the diurnal variation of sport performance. Although studies in this field are limited, the available information shows that compared with sedentary subjects, trained population maintained similar diurnal variations of hematological parameters, homocysteine, and some biochemical markers at rest and even after physical exercise. However, after strength exercises, the circadian rhythms for the majority of oxidative stress and muscle damage markers were altered because of the higher rate of increased pre-post exercises registered in the morning compared with the afternoon and evening. The available studies reveal that the significant circadian variation observed for sport performances could be more likely explained by the alteration of ionic movement and the diurnal fluctuation of homocysteine, lactate, muscle damage, and antioxidant markers.

Latitude affects Morningness-Eveningness: evidence for the environment hypothesis based on a systematic review.

Abstract: Morningness-eveningness (M/E) is an individual trait related to a person's sleep-wake cycle and preference for morning or evening hours. The "environment hypothesis" suggests that M/E is dependent on environmental factors, such as latitude, mean average temperature and photoperiod. We here analyzed a large number of datasets to assess this effect based on a systematic review. Data were from a total of 87 datasets and 35,589 individuals based on 28 countries. Partial correlations correcting for age revealed significant relationships between M/E and latitude, mean yearly temperature, photoperiod and sunset. Evening orientation was related to higher latitude, longer days and later sunset. Morning orientation was related to higher average temperatures. Percentage of females and sunrise time had no significant influence. These variables (sunset, temperature, photoperiod) were then input in a general linear model. The full model showed an influence of age and of sunset on CSM scores, but not of photoperiod and average temperature. Sunset, therefore, seems to be the most important statistical predictor for the observed latitudinal gradient.

The effects of diurnal Ramadan fasting on energy expenditure and substrate oxidation in healthy men.

Abstract: The study aimed to examine the effects of diurnal Ramadan fasting (RF) on substrate oxidation, energy production, blood lipids and glucose as well as body composition. Nine healthy Muslim men (fasting (FAST) group) and eight healthy non-practicing men (control (CNT) group) were assessed pre- and post-RF. FAST were additionally assessed at days 10, 20 and 30 of RF in the morning and evening. Body composition was determined by hydrodensitometry, substrate oxidation and energy production by indirect calorimetry, blood metabolic profile by biochemical analyses and energy balance by activity tracker recordings and food log analyses. A significant group×time interaction revealed that chronic RF reduced body mass and adiposity in FAST, without changing lean mass, whereas CNT subjects remained unchanged. In parallel to these findings, a significant main diurnal effect (morning v. evening) of RF on substrate oxidation (a shift towards lipid oxidation) and blood metabolic profile (a decrease in glucose and an increase in total cholesterol and TAG levels, respectively) was observed, which did not vary over the course of the Ramadan. In conclusion, although RF induces diurnal metabolic adjustments (morning v. evening), no carryover effect was observed throughout RF despite the extended daily fasting period (18·0 (sd 0·3) h) and changes in body composition.

Ratings of Perceived Exertion and Self-reported Mood State in Response to High Intensity Interval Training. A Crossover Study on the Effect of Chronotype.

Abstract: The aim of this study was to investigate the influence of chronotype on mood state and ratings of perceived exertion (RPE) before and in response to acute high intensity interval exercise (HIIE) performed at different times of the day. Based on the morningness-eveningness questionnaire, 12 morning-types (M-types; N=12; age 212 years; height 1795 cm; body mass 7412 kg) and 11 evening-types (E-types; N=11; age 212 years; height 18111 cm; body mass 7611 kg) were enrolled in a randomized crossover study. All subjects underwent measurements of Profile of Mood States (POSM), before (PRE), after 12 (POST12) and 24 hours (POST24) the completion of both morning (08.00 am) and evening (08.00 p.m.) training. Additionally, Global Mood Disturbance (GMD), and Energy Index (EI) were calculated. RPE was obtained PRE and 30 min POST HIIE. Two-way ANOVA with Tuckey’s multiple comparisons test of POMS parameters during morning training showed significant differences in fatigue, vigour and EI at PRE and POST24 between M-types and E-types. In addition, significant chronotype differences were found only in POST12 after the evening HIIE for fatigue, vigour and EI. For what concerns Borg perceived exertion, comparing morning versus evening values in PRE condition, an higher RPE was observed in relation to evening training for M-types (P=0.0107) while E-types showed higher values in the morning (P=0.008). Finally, intragroup differences showed that E-types had a higher ratings of perceived exertion respect to M-types before (P=0.002) and after 30 min (P=0.042) the morning session of HIIE. No significant changes during the evening training session were found. In conclusion, chronotype seems to significantly influence fatigue values, perceived exertions and vigour in relation to HIIE performed at different times of the day. Specifically, E-types will meet more of a burden when undertaking a physical task early in the day. Practical results suggest that performing an high intensity interval exercise at those times of day that do not correspond to subjects’ circadian preference can lead to increased mood disturbances and perceived exertion. Therefore, an athlete’s chronotype should be taken into account when scheduling HIIE.

Comparing Performance During Morning vs. Afternoon Training Sessions in Intercollegiate Basketball Players

Abstract: Time of day is a key factor that influences the optimization of athletic performance. Intercollegiate coaches oftentimes hold early morning strength training sessions for a variety of factors including convenience. However, few studies have specifically investigated the effect of early morning vs. late afternoon strength training on performance indices of fatigue. This is athletically important because circadian and/or ultradian rhythms and alterations in sleep patterns can affect training ability. Therefore, the purpose of the present study was to examine the effects of morning vs. afternoon strength training on an acute performance index of fatigue (countermovement jump height, CMJ), player readiness (Omegawave), and self-reported sleep quantity. We hypothesized that afternoon training sessions would be associated with increased levels of performance, readiness, and self-reported sleep. A retrospective analysis was performed on data collected over the course of the preseason on 10 elite National Collegiate Athletic Association Division 1 male basketball players. All basketball-related activities were performed in the afternoon with strength and conditioning activities performed either in the morning or in the afternoon. The average values for CMJ, power output (Power), self-reported sleep quantity (sleep), and player readiness were examined. When player load and duration were matched, CMJ (58.8 ± 1.3 vs. 61.9 ± 1.6 cm, p = 0.009), Power (6,378.0 ± 131.2 vs. 6,622.1 ± 172.0 W, p = 0.009), and self-reported sleep duration (6.6 ± 0.4 vs. 7.4 ± 0.25 p = 0.016) were significantly higher with afternoon strength and conditioning training, with no differences observed in player readiness values. We conclude that performance is suppressed with morning training and is associated with a decrease in self-reported quantity of sleep.

One night of sleep restriction following heavy exercise impairs 3-km cycling time-trial performance in the morning

Abstract: The goal of this project was to examine the influence of a single night of sleep restriction following heavy exercise on cycling time-trial (TT) performance and skeletal muscle function in the morn...

Diurnal Blood Pressure Rhythmicity in Relation to Environmental and Genetic Cues in Untreated Referred Patients.

Abstract: No previous study has addressed the relative contributions of environmental and genetic cues to the diurnal blood pressure rhythmicity. From 24-hour ambulatory recordings of systolic blood pressure obtained in untreated patients (51% women; mean age, 51 years), we computed the night-to-day ratio in 897 and morning surge in 637. Environmental cues included season, mean daily outdoor temperature, atmospheric pressure, humidity and weekday, and the genetic cues 14 single nucleotide polymorphisms in 10 clock genes. Systolic blood pressure averaged (±SD) 126.7±11.9 mm Hg, night-to-day ratio 0.86±0.07, and morning surge 24.8±10.7 mm Hg. In adjusted analyses, night-to-day ratio was 2.4% higher in summer and 1.8% lower in winter (P<0.001) compared with the annual average with a small effect of temperature (P=0.079); morning surge was 1.7 mm Hg lower in summer and 1.1 mm Hg higher in winter (P<0.001). The other environmental cues did not add to the night-to-day ratio or morning surge variance (P≥0.37). Among the 14 genetic variations, only CLOCK rs180260 was significantly associated with morning surge after adjustment for season, temperature, and other host factors and after Bonferroni correction (P=0.044). In CLOCK rs1801260 C allele carriers (n=83), morning surge was 3.7 mm Hg higher than in TT homozygotes (n=554). Of the night-to-day ratio and morning surge variance, season and temperature explained ≈8% and ≈3%, while for genetic cues, these proportions were ≈1% or less. In conclusion, environmental compared with genetic cues are substantially stronger drivers of the diurnal blood pressure rhythmicity.