Puttonen S, Härmä M, Hublin C. Shift work and cardiovascular disease: pathways from circadian stress to morbidity

Centre of Expertise on Human Factors at Work, Finnish Institute of Occupational Health, FI-00250 Helsinki, Finland.
Scandinavian Journal of Work, Environment & Health (Impact Factor: 3.45). 03/2010; 36(2):96-108. DOI: 10.2307/40967836
Source: PubMed


In order to establish a causal relation between shift work and cardiovascular disease (CVD), we need to verify the pathways from the former to the latter. This paper aims to review the current knowledge of the mechanisms between shift work and CVD. Shift work can increase the risk of CVD by several interrelated psychosocial, behavioral, and physiological mechanisms. The psychosocial mechanisms relate to difficulties in controlling working hours, decreased work-life balance, and poor recovery following work. The most probable behavioral changes are weight gain and smoking. The plausible physiological and biological mechanisms are related to the activation of the autonomic nervous system, inflammation, changed lipid and glucose metabolism, and related changes in the risk for atherosclerosis, metabolic syndrome, and type II diabetes. The data provide evidence for possible disease mechanisms between shift work and CVD, but compelling evidence on any specific mechanism is missing.

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    • "Frequently explored experimental models of circadian disruption, which are mainly focused on the SCN, employ exposure of rodents to constant light [13], altered length of LD period [14] or repeated shifts in LD cycle [2] [15]. Disturbed circadian oscillations can induce causal pathways leading to an increased risk of disease development through physiological, psychosocial and behavioural mechanisms [16]. In rodents, physiological effects of altered light conditions are implicated in metabolic functions, especially in glucose metabolism [12]. "
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    ABSTRACT: Disturbed light–dark (LD) cycles are associated with circadian disruption of physiological and behavioural rhythms and in turn with an increased risk of disease development. However, direct causal links and underlying mechanisms leading to negative health consequences still need to be revealed. In the present study, we exposed male Wistar rats to repeated phase shifts of LD cycle and analysed their ability to cope with mild emotional stressors. In experiment 1, rats were submitted to either a regular 12:12 LD cycle (CTRL rats) or 8-h phase delay shifts applied every 2 days for 5 weeks (SHIFT rats). Subsequently, the behaviour was examined in the open-field, black–white box and elevated plus maze tests. In experiment 2, changes in blood pressure (BP), heart rate (HR) as well as the activity of autonomic nervous system were measured in telemeterised rats in response to open-field and black–white box tests before and after 5-week exposure to shifted LD regime. Locomotor activity was consistently higher in SHIFT than CTRL rats in in the open-field and black–white box tests. Interestingly, in the elevated plus maze, SHIFT rats displayed increased risk assessment and decreased grooming compared to CTRL rats. Anxiety measures were affected only in the black–white box, where SHIFT rats displayed reduced anxiety-like behaviour compared to CTRL rats. Differences in behavioural reactivity between SHIFT and CTRL rats did not correspond with BP and HR changes. However, exposure to phase shifts increased the sympathovagal reactivity in the black–white box. Together, our results demonstrated that disturbed LD conditions decreased emotional reactivity of rats and affected their ability to cope with emotional stressors denoting an additional risk mechanism linking disrupted circadian organisation to adverse health effects.
    No preview · Article · Mar 2016 · Physiology & Behavior
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    • "Relationships among these entraining signals are complicated because lesions of SCN do not diminish the sensitivity of animals to food availability mediated by separate food entrainable oscillators (FEO) located in the dorsomedial (Gooley et al. 2006; Mieda et al. 2006) or ventromedial (Krieger et al. 1977) nucleus of the hypothalamus. Shift work, night work and jet lag are important elements in modern human life, but they can disturb circadian oscillations and have negative health consequences (Puttonen et al. 2010). Epidemiological and clinical studies provide inconclusive results about the negative effects of shift work on cardiovascular diseases (Frost et al. 2009; Wang et al. 2011) and cannot reveal any causal relationship. "
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    ABSTRACT: Effects of phase delay shifts (PDS) of light in combination with moderately increased salt intake (SL) (2%) or time restriction of food (FR) during the light-time (passive phase) on heart rate (HR), blood pressure (BP) and locomotor activity (LA) in radiotelemetry-measured rats were evaluated. PDS decreased amplitude and spectral power of circadian oscillations of HR, BP and LA. Moderately increased SL did not interfere with the circadian rhythmicity of HR, BP or LA. A prominent decrease in amplitude and spectral power of circadian oscillations was observed if food was available during the lighttime. Combination of PDS with FR split cardiovascular and behavioural parameters. In conclusion, food availability during the light-time in combination with PDS decreased amplitude and spectral power of circadian oscillations of BP, HR and LA more than PDS only. Different response of cardiovascular and behavioural parameters to photic and non-photic stimuli can have consequences for shift workers.
    Full-text · Article · Nov 2015 · Biological Rhythm Research
    • "Shift work is associated with impaired health. For example, it has been shown that working shifts increase the risk of sleep disturbances, gastrointestinal and cardiovascular complaints and possibly also cancer (Akerstedt, 2003; Knutsson & Boggild, 2010; Megdal et al., 2005; Puttonen et al., 2010). Sleep disturbances are considered to be the most common problem, especially in rotational shift work and in night work (Akerstedt, 1998, 2003). "
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    ABSTRACT: The aim of this study was to investigate whether different shift work schedules were associated with nonrapid eye movement (NREM)- and/or REM-related parasomnias. A total of 2198 nurses with different work schedules participated in a longitudinal cohort study. The parasomnia questions were included in the fourth wave of the data collection, with a response rate of 74.1%. Logistic regression analyses with the different parasomnias as dependent variables were conducted. Nurses working two shift (day and evening) and nurses working three shift (day, evening and night) rotational schedules had increased risk of confusional arousal, a NREM-related parasomnia, compared to nurses working daytime only (odds ratios = 2.10 and 1.71, respectively). Similarly, nurses working two and three shift rotational schedules had increased risk of nightmares, a REM-related parasomnia (odds ratios = 1.64 and 1.57, respectively). The other parasomnias were not significantly associated with work schedule. Working night shifts only was not associated with any of the parasomnias. In conclusion, confusional arousal and nightmares were more commonly reported by nurses working rotational shift work schedules compared to nurses working daytime only. This is likely related to the circadian rhythm misalignment and sleep deprivation caused by such shift schedules.
    No preview · Article · Nov 2015 · Chronobiology International
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