Twenty-four-hour pattern of operations-related injury occurrence and severity of off-site/on-call volunteer French firefighters.

We assessed the 24-h pattern of operations-related injuries (ORI) experienced by scheduled off-site/on-call French volunteer firefighters (VFF) through analysis of an archival database. Occurrence and severity - evaluated by number of lost work days (LWD) and total medical costs (TMC) - of ORI were explored in terms of risk ratios, respectively, number of ORI/number of service operations (RRORI), number of LWD/number of ORI (RSLWD,) and TMC/number of ORI (RSTMC). Additionally, the collective work performance of all involved VFF was measured in terms of the lag time (LT) between emergency call-center firefighter-answered communication for service of observer-presumed out-of-hospital cardiac arrest (OHCA) and departure of vehicle from fire station to render aid, designated LTOHCA. Cosinor and cross-correlation statistical methods were applied. A total of 252 ORI occurred while performing 146,479 service operations. High-amplitude 24 h variation was detected in RRORI (p < .003), SRLWD (p < .001), SRTMC (p < .012), and LTOHCA (p < .001), all with nocturnal peak time. Coherence was found between the day/night variation of LTOHCA and RRORI (r = 0.7, p < .0002), SRLWD (r = 0.5, p < .02), and SRTMC (r = 0.4, p < .05). This investigation verifies the occurrence and severity of ORI of scheduled off-site/on-call VFF exhibit high-amplitude 24 h patterning with nocturnal excess that closely coincides with their day/night work performance measured by LTOHCA. These findings, which are essentially identical to ones of a previous study entailing on-site/on-call career firefighters, indicate the need for fatigue management and ORI prevention programs not yet available to VFF, who compose the majority of the field service workforce of French fire departments. Abbreviations:FF: firefighters; CFF: career firefighters; VFF: volunteer firefighters; FD: fire department; LTOHCA: lag time (LT) response in min:sec between fire department call-center-answered communication for service of presumed out-of-hospital cardiac arrest (OHCA) and departure from fire station of vehicle to render aid; LWD: lost work days; ORI: operations-related injuries; SRLWD: severity ratio of operations-related injuries in terms of number of lost work days, calculated as number of lost work days/number of operations-related injuries; RRORI: risk ratio of operations-related injuries calculated as number of operations-related injuries/number of operations; SRTMC: severity ratio of operations-related injuries in terms of total medical costs, calculated as total medical costs/number of operations-related injuries; TMC: total medical costs.

Risk of obesity in male shift workers: A chronophysiological approach.

AIMS: Why are some healthy male shift workers (SWers) overweight [body mass index (BMI) >25 and <30] if not obese (BMI >30)? Seven risk factors potentially causing overweight and obesity were evaluated, namely (1) age, (2) physical/sports activity, (3) length of exposure to shift work (SW), (4) speed of shift rotation, (5) tolerance to SW, (6) internal desynchronization of circadian rhythms and (8) night eating (nocturnal nibbling). "New" as well as "old" data, acquired from longitudinal and individual time series of 5-56 days recording span, were reanalyzed. The data were analyzed from a set of field studies of 67 SWers and 53 non-shift workers (non-SWers). To estimate the respective weight of these factors, a multiple regression analysis (MRA) was used among other statistical tools. A similar age-related increase in BMI was validated (with p < 0.001) in both SWers and non-SWers. However, in SWers, desynchronization of rhythms increases the effect of age on BMI. Length of exposure to SW, tolerance to SW and speed of rotation do not seem to play a role as risk factors. Major effects are likely to relate to a sedentary lifestyle (lack of regular physical or sport activities) (MRA with p < 0.01), as well as, presumably, to a nocturnal nibbling of carbohydrates, which mimics the night eating syndrome.

Chronobiologic perspectives of black time--Accident risk is greatest at night: An opinion paper.

Simon Folkard in 1997 introduced the phrase black time to draw attention to the fact that the risk of driving accidents (DA) is greater during the night than day in usually diurnally active persons. The 24 h temporal pattern in DA entails circadian rhythms of fatigue and sleep propensity, cognitive and physical performance, and behavior that are controlled, at least in part, by endogenous clocks. This opinion paper extends the concept of black time to reports of excess nighttime accidents and injuries of workers and nocturnal occurrence of certain man-caused catastrophes. We explore the chronobiology of work-related black time accidents and injuries taking into account laboratory and field investigations describing, respectively, circadian rhythms in cognitive performance and errors and mistakes by employees in the conduct of routine occupational tasks. Additionally, we present results of studies pertaining to 24 h patterns of both the number and relative risk (number of events per h/number of workers exposed per h) of work-related accidents (WRA) and injuries (WRI) as well as indices of performance and alertness of a self-selected homogenous survivor cohort of French firefighters (FFs) to explore two possible explanations of black time, namely, 24 h variation in sleep propensity/drossiness characterized by a nocturnal peak and circadian rhythms in cognitive performance characterized by a nocturnal trough. We propose the 24 h pattern of WRA and WRI, particularly of FFs and other highly skilled self-selected cohorts, is more strongly linked to circadian rhythms of fatigue and sleepiness than cognitive performance. Other possible explanations--suppressed expression of circadian rhythms and/or unmasking of ultradian periodicities in cognitive performance in specific circumstances, e.g., highly stressful work, competitive, or life-threatening settings, are also discussed.

Daily rhythmicity of attention in morning- vs. evening-type adolescents at boarding school under different psychosociological testing conditions.

This study used a single protocol to investigate the respective and related effects of the psychosocial conditions of testing (individual vs. group) and personality on the levels and daily variation of attentional performance of adolescents attending boarding school. From scores obtained on an adapted version of Horne and Ostberg's Morningness-Eveningness Questionnaire (MEQ), 17 male (9 morning-type and 8 evening-type) participants were selected from among 50 volunteers. Attention was measured using a number crossing-out test carried out at four times of the day (07:30, 12:00, 14:00, and 19:30). No main effect of testing mode and personality trait was found on the mean level of performance. Time-of-day had an effect on the level of performance, which differed depending on whether the test was administered in a group or individually and on the morningness and eveningness dimension. The difference between the daily profiles appears to be dependent on the interaction of the factors studied. This study investigated the concept of "group psychological rhythmicity" and highlights the importance of synchronizing social rhythms.