The association between exposure to different aspects of shift work and metabolic risk factors in health care workers, and the role of chronotype

Abstract

ObjectiveShift work has been linked to cardio-metabolic diseases, but insight into different shift work-related aspects and chronotype of shift workers and their relation with metabolic risk factors is limited. This study examined the association between current shift work status, frequency and duration of night shift work, chronotype, and metabolic risk factors in a population of health care workers.MethodsAnthropometrics, questionnaires, and blood samples were collected from 503 shift working and 93 non-shift working health care workers employed in hospitals. Body mass index, waist circumference, cholesterol (total, HDL, LDL), triglycerides, and high-sensitivity C-reactive protein were measured. Associations of current shift work, frequency (non-night shift worker, 1–2, 3–4, ≥5 night shifts/month) and duration of night shift work (non-night shift workers, <10, 10–19, ≥20 years), and shift workers’ chronotype, with metabolic risk factors were studied using linear regression analysis.ResultsCompared to non-shift workers, shift workers’ total cholesterol level was 0.38 mmol/L lower (95%-CI = -0.73 –-0.04) and LDL cholesterol was 0.34 mmol/L lower (95%-CI = -0.60 –-0.08). For all other metabolic risk factors, no differences were found. The association between shift work and LDL cholesterol was especially found among shift workers working night shifts for ≥20 years (B = -0.49 (95%-CI = -0.78 –-0.19)). No differences were found for night shift frequency and chronotype.ConclusionIn this population of health care workers employed in hospitals, no evidence for differences in metabolic risk factors was observed that could underlie a link between shift work and cardio-metabolic diseases. Further research using different aspects of shift work to study the association with metabolic risk factors is recommended.

Shift work, and particularly permanent night shifts, promote dyslipidaemia: A systematic review and meta-analysis

“…We included 43 studies [7,10,16 [36,55], and 9 were unspecified [7,17,38,43,49,68,75,79,81]. Only permanent night shift workers had increased blood level of total cholesterol (SMD = 0.22; 95CI 0.01 to 0.42; p = 0.043; I 2 = 60.3%) (Supplementary Data 6).…”

“…We included 48 studies [ [36,[53][54][55], and 12 were unspecified [17,37,38,43,49,62,67,68,75,79,81,84]. We found significantly increased blood levels of triglycerides among permanent night shift workers (0.18; 0.03 to 0.33; p = 0.017; I 2 = 73.8%), rotating 3 × 8 shift workers (0.09; 0.03 to 0.16; p = 0.004; I 2 = 73.6%), rotating 2 × 12 shift workers (0.07; 0.01 to 0.13; p = 0.017; I 2 = 31.6%), and non-specified shift workers (0.11; 0.03 to 0.18; p = 0.004; I 2 = 80.9%) (Supplementary Data 7).…”

“…We included 46 studies [10,17,23,24,37,38,40,41,43,45,[47][48][49][50][51][52][53][54][55][56][57][58][59]62,[65][66][67][68][69][70][71][73][74][75][76][77][78][79][80][81][82][83][84][85][86]91]. The overall SMD was − 0.08 (95CI − 0.12 to − 0.03; p = 0.001) with an important heterogeneity (I 2 = 85.9%) ( Fig.…”

“…2 and Supplementary Data 9). Among the 46 included studies, 6 studies reported permanent night shift [41,58,67,69,71,82] 43,45,49,62,67,68,75,79,81,84]. We found a significantly lower blood level of c-HDL among permanent night shift workers (SMD = − 0.16; 95CI − 0.32 to 0.00; p = 0.05; I 2 = 72.3%), rotating 3 × 8 shift workers (− 0.10; 95CI − 0.17 to − 0.02; p = 0.018; I 2 = 78.8%), and non-specified shift workers (− 0.08; 95CI − 0.15 to − 0.01; p = 0.027; I 2 = 81.7%).…”

“…Among the 31 studies reporting LDL cholesterol[7,10,17,38,40,43, 48,49,51,52,54,55,62,65-70,74,76-82,84-86,91], permanent night shift was reported in 3 studies [67,69,82], rotating 3 × 8 shift in 12 studies [47,52,54,55,65,66,69,70,76,77,80,85], rotating 2 × 12 shift in 7 studies [10,40,51,74,78,86,91], rotating day shift in 2 studies[53,55], and unspecified in 11 studies(Fig. 2and Supplementary Data 8)[7,17,38,43,49,62,67,68,79,81,84]. Meta-analysis, globally and stratified by type of shift works, as well as meta-regressions, did not retrieve any significant results(Figs.…”