Shift work, and in particular night shift work, is associated with increased health risks, such as cardiovascular and metabolic disorders, increased infection susceptibility, autoimmune diseases, and cancer.
It is hypothesized that these health risks are a consequence of disturbed circadian rhythms resulting from imposed night shift work. The circadian pacemaker controls among other things, the sleep-wake cycle, the endocrine and metabolic pathways and the immune system.
In a recently published study, researchers performed a cross-sectional study using data from 10,201 non-shift workers and 1,062 night shift workers of the Lifelines Cohort study. The results were published in the journal Scientific Reports.
Results from the Study
The researchers used linear regression analyses, adjusted for demographic, lifestyle and occupational factors, to study associations of night shift work characteristics with metabolic risk factors and immune cell counts.
Night shift workers had a higher BMI, were more often overweight (BMI ≥ 25 kg/m2), had a higher waist circumference and higher levels of several immune cell types (leukocytes, monocytes, lymphocytes and basophil granulocytes counts) than non-shift workers.
This observed higher BMI and waist circumference among shift-workers is in line with previous studies, and it indicates that night shift workers may be more prone to develop several diseases, such as type 2 diabetes, cardiovascular disease, hypertension, and cancer.
Some mechanisms for this relationship between night shift and increased BMI or waist circumference include reduced physical activity, higher caloric intake, and shorter sleep duration.
The researchers also found increased counts of leukocytes, mainly monocytes, lymphocytes and basophils in the night-shift workers. There is evidence that having increased levels of (differential) leukocytes is a risk factor for type 2 diabetes, cancer, and cardiovascular diseases.
In general as we can see from this study and from previous ones, having a night work shift can have a negative effect on our health, and according to the studies is mainly due to the changes in sleep patterns, shorter sleep duration, and reduced physical activity in individuals that work at night.
Streng, A.A., Loef, B., Dollé, M.E.T. et al. Night shift work characteristics are associated with several elevated metabolic risk factors and immune cell counts in a cross-sectional study. Sci Rep 12, 2022 (2022). https://doi.org/10.1038/s41598-022-06122-w