Role of Patient Chronotype on Circadian Pattern of Myocardial Infarction: A Pilot Study

Population-based studies indicate the risk of acute myocardial infarction (AMI) is greatest in the morning, during the initial hours of diurnal activity. The aim of this pilot study was to determine whether chronotype, i.e., morningness and eveningness, impacts AMI onset time. The sample comprised 63 morning- and 40 evening-type patients who were classified by the Horne-Östberg Morningness-Eveningness Questionnaire (MEQ) in the hospital after experiencing the AMI. The average wake-up and bed times of morning types were ～2?h earlier than evening types. Although the lag in time between waking up from nighttime sleep and AMI onset during the day did not differ between the two chronotypes, the actual clock-hour time of the peak in the 24-h AMI pattern did. The peak in AMI of morning types occurred between 06:01 and 12:00?h and that of the evening types between 12:01 and 18:00?h. Although the results of this small sample pilot study suggest one's chronotype influences the clock time of AMI onset, larger scale studies, which also include assessment of 24-h patterning of events in neither types, must be conducted before concluding the potential influence of chronotype on the timing of AMI onset. (Author correspondence: dryavuzselvi@yahoo.com).     

Chronotype,gender, and time for sex

The study aimed at testing chronotype and gender differences in the time of day when humans feel the greatest need for sex and the time of day they actually undertake sexual activity. A Polish sample of 565 participants aged between 18 and 57 was tested. In females, regardless of chronotype, the greatest need for sex occurred between 18:00 and 24:00, but a secondary peak appeared only in morning types at 6:00–9:00. In males, the greatest need for sex occurred either in the morning or evening hours: in evening types at 9:00–12:00 and 18:00–3:00; in neither types at 6:00–9:00 and 18:00–24:00; in morning types at 6:00–12:00 and 18:00–24:00. Considering time of day when subjects were undertaking sexual activity most frequently, this appeared between 18:00 and 24:00 for all the participants, and prolonged until 3:00 at night in evening type males. Morningness preference was more strongly related to the timing of need for sex than to the timing of actual sexual activity (r?=??0.275 vs. r?=??0.174), while the timing of desire and the timing of sexual activity were positively, but moderately related (r?=?0.320).     

Light exposure among adolescents with delayed sleep phase disorder: a prospective cohort study

The objective of this study was to compare light exposure and sleep parameters between adolescents with delayed sleep phase disorder (DSPD; n=16, 15.3±1.8 yrs) and unaffected controls (n=22, 13.7±2.4 yrs) using a prospective cohort design. Participants wore wrist actigraphs with photosensors for 14 days. Mean hourly lux levels from 20:00 to 05:00 h and 05:00 to 14:00 h were examined, in addition to the 9-h intervals prior to sleep onset and after sleep offset. Sleep parameters were compared separately, and were also included as covariates within models that analyzed associations with specified light intervals. Additional covariates included group and school night status. Adolescent delayed sleep phase subjects received more evening (p< .02, 22:00-02:00 h) and less morning (p .05, 08:00-09:00 h and 10:00-12:00 h) light than controls, but had less pre-sleep exposure with adjustments for the time of sleep onset (p< .03, 5-7 h prior to onset hour). No differences were identified with respect to the sleep offset interval. Increased total sleep time and later sleep offset times were associated with decreased evening (p< .001 and p= .02, respectively) and morning (p= .01 and p< .001, respectively) light exposure, and later sleep onset times were associated with increased evening exposure (p< .001). Increased total sleep time also correlated with increased exposure during the 9 h before sleep onset (p= .01), and a later sleep onset time corresponded with decreased light exposure during the same interval (p< .001). Outcomes persisted regardless of school night status. In conclusion, light exposure interpretation requires adjustments for sleep timing among adolescents with DSPD. Pre- and post-sleep light exposures do not appear to contribute directly to phase delays. Sensitivity to morning light may be reduced among adolescents with DSPD.     

Light Exposure Among Adolescents With Delayed Sleep Phase Disorder: A Prospective Cohort Study

The objective of this study was to compare light exposure and sleep parameters between adolescents with delayed sleep phase disorder (DSPD; n?=?16, 15.3?±?1.8 yrs) and unaffected controls (n?=?22, 13.7?±?2.4 yrs) using a prospective cohort design. Participants wore wrist actigraphs with photosensors for 14 days. Mean hourly lux levels from 20:00 to 05:00?h and 05:00 to 14:00?h were examined, in addition to the 9-h intervals prior to sleep onset and after sleep offset. Sleep parameters were compared separately, and were also included as covariates within models that analyzed associations with specified light intervals. Additional covariates included group and school night status. Adolescent delayed sleep phase subjects received more evening (p?<?.02, 22:00–02:00?h) and less morning (p?<?.05, 08:00–09:00?h and 10:00–12:00?h) light than controls, but had less pre-sleep exposure with adjustments for the time of sleep onset (p?<?.03, 5–7?h prior to onset hour). No differences were identified with respect to the sleep offset interval. Increased total sleep time and later sleep offset times were associated with decreased evening (p?<?.001 and p?=?.02, respectively) and morning (p?=?.01 and p?<?.001, respectively) light exposure, and later sleep onset times were associated with increased evening exposure (p?<?.001). Increased total sleep time also correlated with increased exposure during the 9?h before sleep onset (p?=?.01), and a later sleep onset time corresponded with decreased light exposure during the same interval (p?<?.001). Outcomes persisted regardless of school night status. In conclusion, light exposure interpretation requires adjustments for sleep timing among adolescents with DSPD. Pre- and post-sleep light exposures do not appear to contribute directly to phase delays. Sensitivity to morning light may be reduced among adolescents with DSPD. (Author correspondence: auger.raymond1@mayo.edu)     

A method to evaluate dynamics and periodicity of hormone secretion

Spontaneous hormone secretory dynamics include tonic and pulsatile components and a number of periodic processes. Circadian variations are usually found for melatonin, TSH and GH, with peak secretions at night, and in cortisol secretion, which peaks in the morning. Free thyroxine (FT4) and insulin-like growth factor (IGF)1 levels do not always change with circadian rhythmicity or show only minor fluctuations. Fractional variations explore the dynamics of secretion related to time intervals, and the rate of change in serum levels represents a signal for the receptorial system and the target organ. We evaluated time-related variations and change dynamics for melatonin, cortisol, TSH, FT4, GH and IGF1 levels in blood samples obtained every 4 h for 24 h from eleven healthy males, ages 35-53 years (mean ? SE 43.6 ± 1.7). Nyctohemeral (i.e., day-night) patterns of hormone secretion levels and the fractional rate of variation between consecutive 4-hourly time-qualified hormone serum levels (calculated as percent change from time 1 to time 2) were evaluated for circadian periodicity using a 24 and 12-h cosine model. A circadian rhythm was validated for serum level changes in cortisol with peaks of the 24-h cosine model at 07:48 h, and melatonin, TSH and GH, with phases at 01:35 h, 23:32 h, and 00:00 h, respectively. A weak, but significant, 12-h periodicity was found for FT4 serum levels, with minor peaks in the morning (10:00 h) and evening (22:00 h), and for IGF1, with minor peaks in the morning (07:40 h) and evening (19:40 h). Circadian rhythmicity was found in the 4-hourly fractional variations with phases of increase or surge at 02:00 h for cortisol, 22:29 h for melatonin, 05:14 h for FT4, and 21:19 h for GH. A significant 12-h periodicity was found for the 4-hourly fractional variations of TSH with two peaks in the morning (decrease or drop at 04:42 h) and afternoon (surge at 16:28 h), whereas IGF1 fractional variation changes did not show a significant rhythmic pattern. In conclusion, the calculation of the time-qualified fractional rate of variation allows evaluation of the dynamics of secretion and the specification of the timepoint(s) of maximal change of secretion, not only for hormones whose secretion is characterized by a circadian pattern of variation, but also for hormones that show no circadian or only weak ultradian (12 h) variations (i.e., FT4).     

Wise “birds” follow their clock: The role of emotional intelligence and morningness–eveningness in diurnal regulation of mood

Emotional intelligence (EI) and morningness–eveningness (M-E) preference have been shown to influence mood states. The present article investigates the way in which these two constructs may interact, influencing morning and evening mood levels. A sample of 172 participants completed a multidimensional mood scale measuring energetic arousal (EA), tense arousal (TA), and hedonic tone at 7:00 and at 22:00. As expected, morning and evening types experienced higher EA at their preferred time of day; effects of M-E on other mood dimensions were weaker. EI was found to correlate with lower TA, but the association was stronger at 22:00, perhaps reflecting the role of EI in managing the social events characteristic for the evening hours. An interactive effect of EI and M-E was found for both diurnal changes and morning levels of EA. Namely, in individuals higher in EI, there appeared a more marked synchrony effect between chronotype and EA, which was absent in those low in EI; individuals higher in EI showed more pronounced diurnal changes in EA characteristic for their chronotype (i.e., higher EA at morning hours in morning chronotypes; higher EA at evening hours in evening chronotypes), while in participants low in EI, diurnal changes in EA were smaller. Moreover, the characteristic positive association between morningness and EA during morning hours was apparent only in those high in EI. These findings suggest that individual differences in circadian variation in mood reflect several factors, including an endogenous rhythm in energy, the distribution of social activities throughout the day, and the person’s awareness of their own energy level.     

Theophylline Dose-Concentration Relationship of a 12-Hourly Nuelin SA Regimen Supplemented with Nocturnal Nuelin Liquid in Healthy Volunteers

Twelve healthy male volunteers who were diurnally active between 05:00 and 23:00 took part in a randomized, multiple-dose, double-blind, four-way, crossover study to determine the relationship between the dose of a nonsus-tained-release theophylline (NSRT) formulation added to the evening administration of a 12-hourly sustained-release theophylline (SRT) regimen and the elevation of the early morning (between 02:00 and 05:00) steady-state plasma theophylline concentration. The four treatments were 250 mg Nuelin SA (sustained-release theophylline) every 12 h plus either placebo or Nuelin liquid (non-sustained-release theophylline) equivalent to 100 mg, 200 mg, or 300 mg of theophylline. Without evening supplementation (placebo), the early morning plasma theophylline concentrations were 13% lower than the average 24-h concentration. but with evening supplementation the early morning plasma theophylline concentration could be raised up to and above the average 24-h Concentration. A prediction equation for the early morning plasma theophylline concentration as a function of the additional evening dose of Nuelin liquid, and of the steady-state evening trough plasma theophylline concentration without evening supplementation, was established. This prediction equation can be used to determine the additional evening dose of Nuelin liquid (administered at 19:00) needed to reduce early morning bronchoconstriction in asthmatic patients who are on a 12-hourly Nuelin SA (drug administered at 07:00 and 19:00) regimen.     

Theophylline Dose-Concentration Relationship of a 12-Hourly Nuelin SA Regimen Supplemented with Nocturnal Nuelin Liquid in Healthy Volunteers

Twelve healthy male volunteers who were diurnally active between 05:00 and 23:00 took part in a randomized, multiple-dose, double-blind, four-way, crossover study to determine the relationship between the dose of a nonsus-tained-release theophylline (NSRT) formulation added to the evening administration of a 12-hourly sustained-release theophylline (SRT) regimen and the elevation of the early morning (between 02:00 and 05:00) steady-state plasma theophylline concentration. The four treatments were 250 mg Nuelin SA (sustained-release theophylline) every 12 h plus either placebo or Nuelin liquid (non-sustained-release theophylline) equivalent to 100 mg, 200 mg, or 300 mg of theophylline. Without evening supplementation (placebo), the early morning plasma theophylline concentrations were 13% lower than the average 24-h concentration. but with evening supplementation the early morning plasma theophylline concentration could be raised up to and above the average 24-h Concentration. A prediction equation for the early morning plasma theophylline concentration as a function of the additional evening dose of Nuelin liquid, and of the steady-state evening trough plasma theophylline concentration without evening supplementation, was established. This prediction equation can be used to determine the additional evening dose of Nuelin liquid (administered at 19:00) needed to reduce early morning bronchoconstriction in asthmatic patients who are on a 12-hourly Nuelin SA (drug administered at 07:00 and 19:00) regimen.     

24-hour pattern in lag time of response by firemen to calls for urgent medical aid

The aim of the study was to assess the group 24-h pattern of lag time (LT) in response by regular and volunteer firemen (RFM and VFM) to calls for medical help (CFMH), specifically calls for out-of-hospital cardiac arrest (OHCA). LT, duration in min between a CFMH and departure of service vehicle equipped with a semiautomated defibrillator and generally staffed with four well-trained and ready-to-go FM, represents the integrated duration of several processes, each with separate reaction and decision-making times. The exact time of each CFHM (in min, h, day, month, yr) was recorded electronically, and the exact departure time from the station of the responding FM vehicle was recorded by an on-duty FM. Overall, CFMH made up 53 ± 9% (SEM) of all emergencies calls for aid. To standardize the study methods, the reported findings are based on 568 CFMH specifically regarding OHCA that occurred during the 4-yr study span (January 2005 to December 2008). CFMH exhibited a 24-h pattern with a major peak at 10:00 h (mean ± SEM: n = 9.5 ± 1.6) and major trough at 01:00 h (n = 1.3 ± 0.3; t test, p??.05). In CFMH/h pooled time series, ANOVA-detected differences between the hourly means (p?相似文献   

Comparison of the efficacy of morning versus evening administration of olmesartan in uncomplicated essential hypertension

A total of 18 diurnally active subjects with uncomplicated, mild to moderate, essential hypertension were studied to compare the efficacy of the morning versus evening administration of an oral olmesartan medication. After a two-week, wash-out/placebo run-in period, subjects with clinic diastolic blood pressure (DBP) > or = 90 mm Hg and <110 mm Hg began 12 weeks of 20 mg olmesartan medoxomil tablet therapy at 08:00 h daily. Four of the 18 subjects required dose escalation to 40 mg at eight weeks because of clinic DBP > or = 90 mm Hg. After the 12-week period of once-a-day 08:00 h treatment, subjects were immediately switched to an evening (20:00 h) drug-ingestion schedule for another 12-week period without change in dose. Subjects underwent 24 h ambulatory blood pressure monitoring (ABPM) before the initiation of morning treatment and at the end of both the 12-week morning and evening treatment arms. Dosing time did not exert statistically significant differences on the efficacy of olmesartan: the reduction from baseline in the 24 h mean systolic (SBP) and DBP was, respectively, 18.8 and 14.6 mm Hg with morning dosing and 16.1 and 13.2 mm Hg with evening dosing (p>0.152 between groups). The amplitude of the BP 24 h pattern did not vary with dosing time, indicating full 24 h BP reduction no matter the clock hour of treatment. Although, the BP-lowering effect was somewhat better with morning dosing, the results of this study suggest that the studied olmesartan medoxomil preparation efficiently reduces BP when ingested in the morning (08:00 h) or evening (20:00 h) in equivalent manner, based on statistical testing, throughout the 24 h.     

24-hour Pattern in Lag Time of Response by Firemen to Calls for Urgent Medical Aid

The aim of the study was to assess the group 24-h pattern of lag time (LT) in response by regular and volunteer firemen (RFM and VFM) to calls for medical help (CFMH), specifically calls for out-of-hospital cardiac arrest (OHCA). LT, duration in min between a CFMH and departure of service vehicle equipped with a semiautomated defibrillator and generally staffed with four well-trained and ready-to-go FM, represents the integrated duration of several processes, each with separate reaction and decision-making times. The exact time of each CFHM (in min, h, day, month, yr) was recorded electronically, and the exact departure time from the station of the responding FM vehicle was recorded by an on-duty FM. Overall, CFMH made up 53?±?9% (SEM) of all emergencies calls for aid. To standardize the study methods, the reported findings are based on 568 CFMH specifically regarding OHCA that occurred during the 4-yr study span (January 2005 to December 2008). CFMH exhibited a 24-h pattern with a major peak at 10:00?h (mean?±?SEM: n?=?9.5?±?1.6) and major trough at 01:00?h (n?=?1.3?±?0.3; t test, p?<?.001). From year to year and season to season, a 24-h pattern was detected in the total of CFMH/h with two peaks (～10:00 and ～17:00h) and two troughs (～01:00 and ～15:00?h) (analysis of variance [ANOVA], p?<?.01; Cosinor, p?<?.05 to?<?.003), with neither season- nor year-related differences (χ², p?>?.05). In CFMH/h pooled time series, ANOVA-detected differences between the hourly means (p?<?.01), and Cosinor analysis validated a 24-h rhythm (p?<?.002). In raw data, the longest LT, indicative of poorest performance, occurred at 05:00?h (8.8?±?0.7?min) and the trough of LT, indicative of best performance, at 16:00?h (4.3?±?0.8?min (t test, p?<?.02). 24-h patterning in LT was validated both by ANOVA of hourly means (p?<?.0006) and Cosinor analysis (p?<?.05), with longest LT ～05:00?h and shortest LT ～16.00?h for data of the individual yearly time-series data. The 24-h LT rhythm was also validated in the pooled time series by Cosinor (p?<?.0001), with the 24-h mean?±?SEM?=?6?±?0.17?min and acrophase (peak) of 03:00?h?±?88?min (SD). Curve patterns of CFMH/h and LT/h differed widely. As a group phenomenon, the LT 24-h rhythm mimics the 24-h pattern of performance, as demonstrated by many laboratory and field investigations. The stability of the LT rhythm between years and seasons and its weak relationship with the CFMH 24-h pattern favors the hypothesis of an endogenous component or origin. The nighttime trough of performance is presumably linked to the elevated risk of work accidents in the same population of FM.     

Morning preference in onset of symptomatic third-degree atrioventricular heart block

The aim of this study was to examine 24h patterning in the symptoms indicative of third-degree atrio-ventricular (AV) heart block. We found a total of 227 cases (126 men and 101 women) of third-degree AV block that had been diagnosed by the Emergency Medical Department of the St. Anna Hospital in Ferrara, Italy between 1990 and 2001. Determination of the hour of onset of symptomatic third-degree AV block, however, was possible and listed in the records of only 161 or 70.9% of the cases (92 men and 69 women). The onset time of every event was categorized into one of four 6h spans of the 24h: night (00:00-05:59h), morning (06:00-11:59h), afternoon (12:00-17:59h), and evening (18:00-23:59h). The onset of the symptoms of third-degree AV block in the sample of 161 cases was significantly greater in the morning between 06:00 and 11:59h than any other 6h span of the day and night (chi2-test; p < 0.001). The same phenomenon was substantiated in the subgroup of the 92 males (chi2; p < 0.0001), although it could not be detected for the smaller subgroup of 69 women. The 24h pattern, with morning preference, in the onset of symptomatic third-degree AV block is similar to the one in sudden cardiac death and cardiogenic cardiac arrest. The etiology of the 24h pattern in symptomatic AV block is unknown; it may be an expression of intrinsic biological rhythmicity within the heart tissue or its control system, and/or the timing of environmental triggers resulting in coronary ischemia.     

Older poor-sleeping women display a smaller evening increase in melatonin secretion and lower values of melatonin and core body temperature than good sleepers

Melatonin concentration and core body temperature (CBT) follow endogenous circadian biological rhythms. In the evening, melatonin level increases and CBT decreases. These changes are involved in the regulation of the sleep-wake cycle. Therefore, the authors hypothesized that age-related changes in these rhythms affect sleep quality in older people. In a cross-sectional study design, 11 older poor-sleeping women (aged 62-72 yrs) and 9 older good-sleeping women (60-82 yrs) were compared with 10 younger good-sleeping women (23-28 yrs). The older groups were matched by age and body mass index. Sleep quality was assessed by the Pittsburgh Sleep Quality Index questionnaire. As an indicator of CBT, oral temperature was measured at 1-h intervals from 17:00 to 24:00?h. At the same time points, saliva samples were collected for determining melatonin levels by enzyme-linked immunosorbent assay (ELISA). The dim light melatonin onset (DLMO), characterizing the onset of melatonin production, was calculated. Evening changes in melatonin and CBT levels were tested by the Friedman test. Group comparisons were performed with independent samples tests. Predictors of sleep-onset latency (SOL) were assessed by regression analysis. Results show that the mean CBT decreased in the evening from 17:00 to 24:00?h in both young women (from 36.57°C to 36.25°C, p < .001) and older women (from 36.58°C to 35.88°C, p < .001), being lowest in the older poor sleepers (p < .05). During the same time period, mean melatonin levels increased in young women (from 16.2 to 54.1 pg/mL, p < .001) and older women (from 10.0 to 23.5 pg/mL, p < .001), being lowest among the older poor sleepers (from 20:00 to 24:00?h, p < .05 vs. young women). Older poor sleepers also showed a smaller increase in melatonin level from 17:00 to 24:00?h than older good sleepers (mean?±?SD: 7.0?±?9.63 pg/mL vs. 15.6?±?24.1 pg/mL, p = .013). Accordingly, the DLMO occurred at similar times in young (20:10?h) and older (19:57?h) good-sleeping women, but was delayed ～50?min in older poor-sleeping women (20:47?h). Older poor sleepers showed a shorter phase angle between DLMO and sleep onset, but a longer phase angle between CBT peak and sleep onset than young good sleepers, whereas older good sleepers had intermediate phase angles (insignificant). Regression analysis showed that the DLMO was a significant predictor of SOL in the older women (R(2)?=?0.64, p < .001), but not in the younger women. This indicates that melatonin production started later in those older women who needed more time to fall asleep. In conclusion, changes in melatonin level and CBT were intact in older poor sleepers in that evening melatonin increased and CBT decreased. However, poor sleepers showed a weaker evening increase in melatonin level, and their DLMO was delayed compared with good sleepers, suggesting that it is not primarily the absolute level of endogenous melatonin, but rather the timing of the circadian rhythm in evening melatonin secretion that might be related to disturbances in the sleep-wake cycle in older people.     

Comparison of the Efficacy of Morning versus Evening Administration of Olmesartan in Uncomplicated Essential Hypertension

A total of 18 diurnally active subjects with uncomplicated, mild to moderate, essential hypertension were studied to compare the efficacy of the morning versus evening administration of an oral olmesartan medication. After a two‐week, wash‐out/placebo run‐in period, subjects with clinic diastolic blood pressure (DBP) ≥90 mm Hg and <110 mm Hg began 12 weeks of 20 mg olmesartan medoxomil tablet therapy at 08:00 h daily. Four of the 18 subjects required dose escalation to 40 mg at eight weeks because of clinic DBP≥90 mm Hg. After the 12‐week period of once‐a‐day 08:00 h treatment, subjects were immediately switched to an evening (20:00 h) drug‐ingestion schedule for another 12‐week period without change in dose. Subjects underwent 24 h ambulatory blood pressure monitoring (ABPM) before the initiation of morning treatment and at the end of both the 12‐week morning and evening treatment arms. Dosing time did not exert statistically significant differences on the efficacy of olmesartan: the reduction from baseline in the 24 h mean systolic (SBP) and DBP was, respectively, 18.8 and 14.6 mm Hg with morning dosing and 16.1 and 13.2 mm Hg with evening dosing (p>0.152 between groups). The amplitude of the BP 24 h pattern did not vary with dosing time, indicating full 24 h BP reduction no matter the clock hour of treatment. Although, the BP‐lowering effect was somewhat better with morning dosing, the results of this study suggest that the studied olmesartan medoxomil preparation efficiently reduces BP when ingested in the morning (08:00 h) or evening (20:00 h) in equivalent manner, based on statistical testing, throughout the 24 h.     

The Circadian Energy Scale (CIRENS): two simple questions for a reliable chronotype measurement based on energy

This study presents the Circadian Energy Scale (CIRENS), a very short and simple chronotype measurement tool based on energy. The CIRENS consists of two introspective questions about the usual energy level (very low, low, moderate, high, or very high, scored 1 to 5) in the morning and in the evening. The difference between energy level scores (-4 to 4) felt by respondents in the evening and morning defines the chronotype score and classification. A concurrent validity analysis of the CIRENS with the widely used Horne and ?stberg Morningness-Eveningness Questionnaire (MEQ) was conducted using a sample of 225 college students, and with MSFsc, a sleep-based chronotype assessment tool based on the Munich Chronotype Questionnaire (MCTQ), using a sample of 34,530 subjects (18-83 yrs, 27% males). This large sample was collected in a Web survey for behavioral correlates of the CIRENS with variables previously associated with chronotype differences. The correlation of the CIRENS chronotype score was r?=?-.70 with the MEQ and r?=?.32 with the MSFsc. CIRENS chronotype scores declined with age and were not affected by sex. Both CIRENS and MSFsc chronotype scores were related to differences in tobacco, caffeine, and cola soft-drink consumption (all higher in evening types). The CIRENS provides a simple chronotype index and a measure of absolute energy throughout the day and seems to be a reliable chronotype assessment tool that may be useful both clinically and for large-scale studies.     

24-hour pattern of work-related injury risk of French firemen: nocturnal peak time

The first aim of the study was to assess clock-time patterning of work-related injuries (WRIs) of firemen (FM) of Sa?ne et Loire-71 (France) during the 4-yr span of 1 January 2004 to 31 December 2007. FM of this service are legally required to log every WRI and seek its evaluation by the medical service, whether the WRI was the result of worksite duties or exercise/sport activities at the station. WRI was defined specifically as a (nonexercise, nonsport, and nonemotional/stress) work-associated trauma, verified both by log book and medical records. For the corresponding years, the 24-h pattern of emergency calls (Calls) plus road traffic (Traffic) on the main roads of the service area was also assessed. Relative risk (R) of WRI was calculated as the quantity of WRIs/h divided by the quantity of Call responses/h?×?1000, which takes into account the number of at-risk FM/unit time, since each dispatched emergency vehicle is staffed with 4 FM. Comparably trained regular (RFM) and volunteer (VFM) FM experienced a total of 187 WRIs. The 24-h WRI curve patterns of RFM and VFM were correlated (r?=?0.4, p??.05). Analysis of variance (ANOVA) validated comparable clock-time patterns in WRIs of RFM and VFM each year and each season (all p??.0006; Cosinor analysis, p?相似文献   

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The aim of this study was to examine 24h patterning in the symptoms indicative of third-degree atrio-ventricular (AV) heart block. We found a total of 227 cases (126 men and 101 women) of third-degree AV block that had been diagnosed by the Emergency Medical Department of the St. Anna Hospital in Ferrara, Italy between 1990 and 2001. Determination of the hour of onset of symptomatic third-degree AV block, however, was possible and listed in the records of only 161 or 70.9% of the cases (92 men and 69 women). The onset time of every event was categorized into one of four 6h spans of the 24h: night (00:00–05:59h), morning (06:00–11:59h), afternoon (12:00–17:59h), and evening (18:00–23:59h). The onset of the symptoms of third-degree AV block in the sample of 161 cases was significantly greater in the morning between 06:00 and 11:59h than any other 6h span of the day and night (χ²-test; p<0.001). The same phenomenon was substantiated in the subgroup of the 92 males (χ²; p<0.0001), although it could not be detected for the smaller subgroup of 69 women. The 24h pattern, with morning preference, in the onset of symptomatic third-degree AV block is similar to the one in sudden cardiac death and cardiogenic cardiac arrest. The etiology of the 24h pattern in symptomatic AV block is unknown; it may be an expression of intrinsic biological rhythmicity within the heart tissue or its control system, and/or the timing of environmental triggers resulting in coronary ischemia.     

Chronotype regulates the neural basis of response inhibition during the daytime

Studies have elucidated the various modulatory effects of chronotype and time-of-day on task-dependent brain activity, but it is unclear how chronotype and time-of-day regulate brain activity in response inhibition tasks. To address this question, we used functional magnetic resonance imaging (fMRI) to explore the effects of chronotype and time-of-day on response inhibition in normal day-night conditions. Morning-type (MT) and evening-type (ET) participants conducted the stop-signal task in morning (08:00–12:00 hours) and evening (19:00–23:00 hours) sessions. The results showed that inhibition-related cerebral responses in the medial frontal gyrus (MFG), middle cingulate cortex (MCC), thalamus and other typical regions for the execution of response inhibition significantly decreased from morning to evening in MT participants, whereas activity in the right inferior frontal gyrus (IFG)/insula, MFG, MCC and thalamus remained stable or increased in ET participants. The chronotypical differences in homeostatic sleep pressure may explain the observed individual differences in maintaining cognition-related cortical activation. These results suggest the importance of considering chronotype and time-of-day in the design and analysis of cognitive neuroscience studies.     

Influence of Chronotype,Season, and Sex of Subject on Sleep Behavior of Young Adults

The aim of this study was to investigate whether sex, season, and/or chronotype influence the sleep behavior of university students. Detailed data were collected on activity/rest patterns by wrist actigraphy combined with diaries. Thirty‐four medical students (19 female and 15 male) were monitored by Actiwatch® actometers for 15 consecutive days in May and again in November. The data of a modified Horne and Östberg chronotype questionnaire, which were collected from 1573 female and 1124 male medical school students surveyed in the spring and autumn over an eight‐year period, were evaluated. Actiwatch® sleep analysis software was used to process the activity data with statistical analyses performed with ANOVA. We found no significant sex‐specific differences in sleep efficiency, sleep onset latency, or actual sleep‐time duration. However, we did find a difference in sleep efficiency between morning and evening types, with morning types having a higher sleep efficiency (87.9%, SD=1.3) than evening types (84.3%, SD=0.87%; p=0.007). Seasonal differences were also detected: the actual sleep‐time duration in autumn was significantly longer (mean 6.9 h, SD=0.13 h) than in spring (6.6 h, SD=0.1 h; p=0.013). Evaluation of the chronotype questionnaire data showed that individuals with no special preference for morningness or eveningness (i.e., so‐called intermediates) were most common. The distribution of chronotypes was related to the sex of subject. Men displayed eveningness significantly more often than women (28.9% males vs. 20.8% females; p<0.001), while females exhibited greater morningness (20.3% females vs.15.6% males; p<0.001). Sex influences chronotype distribution, but not actual sleep time‐duration, sleep onset latency, or sleep efficiency. The latter, however, differed among chronotypes, while actual sleep‐time duration was affected by season.     

Chronotype and postmenopausal breast cancer risk among women in the California Teachers Study

ABSTRACT

Chronotype is the behavioral manifestation of an individual’s underlying circadian rhythm, generally characterized by one’s propensity to sleep at a particular time during the 24 hour cycle. Evening chronotypes (“night owls”) generally suffer from worse physical and mental health compared to morning chronotypes (“morning larks”) – for reasons that have yet to be explained. One hypothesis is that evening chronotypes may be more susceptible to circadian disruption, a condition where the coordinated timing of biologic processes breaks down. The role of chronotype as an independent or modifying risk factor for cancer has not been widely explored. The objective of the current study was to evaluate the risk of breast cancer associated with chronotype in a case-control study nested within the California Teachers Study (CTS) cohort. The study population consisted of 39686 post-menopausal CTS participants who provided information on chronotype by completing a questionnaire in 2012–2013. 2719 cases of primary invasive breast cancer diagnosed from 1995/1996 through completion of the chronotype questionnaire were identified by linkage of the CTS to the California Cancer Registry. 36967 CTS participants who had remained cancer-free during this same time period served as controls. Chronotype was ascertained by responses to an abbreviated version of the Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ) and was characterized into five categories: definite morning, more morning than evening, neither morning or evening, more evening than morning, definite evening. Multivariable unconditional logistic regression analyses were performed to estimate the odds ratios (ORs) and 95% confidence intervals (95% CIs) for each of the chronotypes, adjusted for established breast cancer risk factors. Compared to definite morning types, definite evening types had an increased risk of breast cancer with elevated ORs that were statistically significant in both the crude (OR = 1.24, 95% CI: 1.10–1.40) and fully-adjusted models (OR = 1.20, 95% CI: 1.06–1.35). The risk estimates in the fully-adjusted model for all other chronotypes did not significantly differ from one. These results suggest that evening chronotype may be an independent risk factor for breast cancer among a population of women who are not known to have engaged in any substantial night shift work. Further research in other populations of non-shift workers is warranted.