Effects of shift work on the eating behavior of police officers on patrol

Recent studies indicate that the timing of food intake can significantly affect metabolism and weight management. Workers operating at atypical times of the 24-h day are at risk of disturbed feeding patterns. Given the increased risk of weight gain, obesity and metabolic syndrome in shift working populations, further research is required to understand whether their eating behavior could contribute to these increased metabolic risks. The objective of this study was to characterize the dietary patterns of police officers across different types of shifts in their natural environments. Thirty-one police officers (six women; aged 32.1 +/- 5.4 years, mean +/- SD) from the province of Quebec, Canada, participated in a 28- to 35-day study, comprising 9- to 12-h morning, evening, and night shifts alternating with rest days. Sleep and work patterns were recorded with actigraphy and diaries. For at least 24 h during each type of work day and rest day, participants logged nutrient intake by timestamped photographs on smartphones. Macronutrient composition and caloric content were estimated by registered dieticians using the Nutrition Data System for Research database. Data were analyzed with linear mixed effects models and circular ANOVA. More calories were consumed relative to individual metabolic requirements on rest days than both evening- and night-shift days (p = 0.001), largely sourced from increased fat (p = 0.004) and carbohydrate (trend, p = 0.064) intake. Regardless, the proportions of calories from carbohydrates, fat, and protein did not differ significantly between days. More calories were consumed during the night, between 2300 h and 0600 h, on night-shift days than any other days (p < 0.001). Caloric intake occurred significantly later for night-shift days (2308 h 0114 h, circular mean +/- SD) than for rest days (1525 h +/- 0029 h; p < 0.01) and was dispersed across a longer eating window (13.9 h 3.1 h vs. 11.3 h +/- 1.8 h, mean +/- SD). As macronutrient proportions were similar and caloric intake was lower, the finding of later meals times on night-shift days versus rest days is consistent with emerging hypotheses that implicate the biological timing of food intake-rather than its quantity or composition-as the differentiating dietary factor in shift worker health.Circadian clocks in health and diseas

The influence of split sleep-wake schedules and daytime sleep strategies on neurobehavioural performance

Demand for 24-h access to services and goods has led to an increase in the number of employees engaged in shiftwork. However, while shiftwork has become necessary to meet community expectations, it has serious consequences for health and safety. The risk of fatigue-related accidents and injuries is a significant problem for the shift working population. This is because shiftwork places restrictions on the opportunities available for workers to obtain sleep. Shiftworkers, especially those who work night shifts, must often stay awake for long hours and sleep at times inconsistent with their body clocks, so sleep loss is common. This dissertation evaluates alternative options for arranging sleep that could potentially optimise neurobehavioural function in circumstances where long nocturnal sleep episodes are not possible. Two main approaches were used to address these aims. The first was to assess the effectiveness of split sleep-wake schedules at sustaining neurobehavioural function around the clock – with and without sleep restriction – which could have implications for work rosters in certain safety-critical industries. The second approach was to assess the effectiveness of different arrangements of daytime sleep at ameliorating the decline of night-time performance, which could have implications for the sleep strategies shiftworkers employ before and after night shifts

The influence of split sleep-wake schedules and daytime sleep strategies on neurobehavioural performance

Demand for 24-h access to services and goods has led to an increase in the number of employees engaged in shiftwork. However, while shiftwork has become necessary to meet community expectations, it has serious consequences for health and safety. The risk of fatigue-related accidents and injuries is a significant problem for the shift working population. This is because shiftwork places restrictions on the opportunities available for workers to obtain sleep. Shiftworkers, especially those who work night shifts, must often stay awake for long hours and sleep at times inconsistent with their body clocks, so sleep loss is common. This dissertation evaluates alternative options for arranging sleep that could potentially optimise neurobehavioural function in circumstances where long nocturnal sleep episodes are not possible. Two main approaches were used to address these aims. The first was to assess the effectiveness of split sleep-wake schedules at sustaining neurobehavioural function around the clock – with and without sleep restriction – which could have implications for work rosters in certain safety-critical industries. The second approach was to assess the effectiveness of different arrangements of daytime sleep at ameliorating the decline of night-time performance, which could have implications for the sleep strategies shiftworkers employ before and after night shifts.Associated Grant:Australian Research Council; RTS; APA; Bushfire CRCAssociated Grant Code:DP13010484

Metabolic and cardiovascular consequences of shift work: The role of circadian disruption and sleep disturbances

Shift work, defined as work occurring outside typical daytime working hours, is associated with an increased risk of various non-communicable diseases, including diabetes and cardiovascular disease. Disruption of the internal circadian timing system and concomitant sleep disturbances is thought to play a critical role in the development of these health problems. Indeed, controlled laboratory studies have shown that short-term circadian misalignment and sleep restriction independently impair physiological processes, including insulin sensitivity, energy expenditure, immune function, blood pressure and cardiac modulation by the autonomous nervous system. If allowed to persist, these acute effects may lead to the development of cardiometabolic diseases in the long term. Here, we discuss the evidence for the contributions of circadian disruption and associated sleep disturbances to the risk of metabolic and cardiovascular health problems in shift workers. Improving the understanding of the physiological mechanisms affected by circadian misalignment and sleep disturbance will contribute to the development and implementation of strategies that prevent or mitigate the cardiometabolic impact of shift work.Circadian clocks in health and diseas

Light and melatonin treatment for shift work

Between 10 and 30% of workers carry out night work at least once a month and 12–13% are working on rotating or regular night shifts. These atypical work schedules cause irregular, fragmented sleep patterns, as well as alertness and performance impairments at night. Atypical work schedules result in circadian misalignment, a state of desynchronization between the endogenous circadian system and the environment. Working at night also produces a state of internal desynchronization between several levels of the circadian system. Circadian adaptation to a night-oriented schedule is a gradual process requiring extended, consistent, and regular exposure to the altered work-rest cycle. There is a high degree of variability in the capacity of individuals to adapt to night schedules and it is estimated only 1 out of 4 workers is able to do so without specific interventions to facilitate circadian phase shifts. As light is the must powerful synchronizer of human circadian rhythms, countermeasures based on strategic light-dark interventions can favor circadian adaptation to atypical work schedules or modulate the secretion of melatonin at night. Melatonin, a hormone secreted by the pineal gland at night can also be administered exogenously to promote sleep in the daytime and shift human circadian rhythms. Most of our knowledge on the resetting and melatonin suppressive effects of light are based on the study of non-shift working populations in highly controlled laboratory conditions. In the field, exogenous melatonin proved useful to extend daytime sleep, although, still today, its resetting effects of shift workers' circadian rhythms remain unclear. The aim of this article is to review the latest scientific evidence on the usefulness of strategic light-dark interventions and on the use of melatonin and melatonin agonists prior to daytime sleep periods in shift working populations

Is it on? An algorithm for discerning wrist-accelerometer non-wear times from sleep/wake activity

The accuracy of sleep/wake estimates derived with actigraphy is often dependent on researchers being able to discern non-wear times from sleep or quiescent wakefulness when confronted by discrepancies in a sleep log. Without knowing when an accelerometer is being worn, non-wear could be inferred from periods of inactivity unlikely to occur while in bed. Data collected in our laboratory suggest that more than 50% of inactive periods during time in bed are <8 min in duration. This duration may be an appropriate minimum threshold for routine non-wear classification during self-reported wake. Higher thresholds could be chosen to derive non-wear definitions for self-reported bedtimes depending on the desired level of certainty. To determine non-wear at thresholds of 75%, 95% and 99%, for example, would require periods of inactivity lasting ≥18 min, ≥53 min and ≥85 min, respectively

Food consumption and food choice following one week of sleep restriction a pilot study /

There is evidence to suggest that restricting sleep may result in overconsumption of food and poor food choices. This has been attributed to disruption in appetite hormones following sleep restriction (SR). The aim of this study was to investigate food consumption and food choices before and after either one week of SR or a control condition consisting of one week of 8 h time in bed (TIB)

Disturbance of the Circadian System in Shift Work and Its Health Impact

The various non-standard schedules required of shift workers force abrupt changes in the timing of sleep and light-dark exposure. These changes result in disturbances of the endogenous circadian system and its misalignment with the environment. Simulated night-shift experiments and field-based studies with shift workers both indicate that the circadian system is resistant to adaptation from a day- to a night-oriented schedule, as determined by a lack of substantial phase shifts over multiple days in centrally controlled rhythms, such as those of melatonin and cortisol. There is evidence that disruption of the circadian system caused by night-shift work results not only in a misalignment between the circadian system and the external light-dark cycle, but also in a state of internal desynchronization between various levels of the circadian system. This is the case between rhythms controlled by the central circadian pacemaker and clock genes expression in tissues such as peripheral blood mononuclear cells, hair follicle cells, and oral mucosa cells. The disruptive effects of atypical work schedules extend beyond the expression profile of canonical circadian clock genes and affects other transcripts of the human genome. In general, after several days of living at night, most rhythmic transcripts in the human genome remain adjusted to a day-oriented schedule, with dampened group amplitudes. In contrast to circadian clock genes and rhythmic transcripts, metabolomics studies revealed that most metabolites shift by several hours when working nights, thus leading to their misalignment with the circadian system. Altogether, these circadian and sleep-wake disturbances emphasize the all-encompassing impact of night-shift work, and can contribute to the increased risk of various medical conditions. Here, we review the latest scientific evidence regarding the effects of atypical work schedules on the circadian system, sleep and alertness of shift-working populations, and discuss their potential clinical impacts.</p

No first night shift effect observed following a nocturnal main sleep and a prophylactic 1-h afternoon nap.

Sargent, C ORCiD: 0000-0001-5340-4701Neurobehavioural impairment on the first night shift is often greater than on subsequent night shifts due to extended wakefulness. The aim of the study was to determine whether a 1-h afternoon nap prior to the first night shift is sufficient to produce neurobehavioural performance at levels comparable to the second night shift. Twelve male volunteers (mean age 22.9 years) participated in a laboratory protocol that simulated two 12-h night shifts. A nap preceded the first shift and a 7-h daytime sleep was scheduled between shifts. Neurobehavioural performance and subjective sleepiness measured across each night did not significantly differ between first and second shifts