Impact of Long- term Night shift

Impact of Long- term night shift work has been linked to an increased risk of atrial fibrillation and coronary heart disease, according to research

According to study published in the European Heart Journal, those who work night shifts are more likely to develop atrial fibrillation (AF), an irregular and sometimes excessively fast heart rhythm.

The goal of this study was to see if current and previous night shift work were linked to atrial fibrillation (AF) and if this link was influenced by genetic vulnerability. A secondary goal was to assess its links to coronary heart disease (CHD), stroke, and heart failure (HF).

The UK Biobank contained 283 657 participants in paid employment or self-employment without AF and 276 009 participants at baseline who were free of CHD, stroke, and HF. 5777 incident AF instances were observed with a median follow-up of 10.4 years. There was a considerable increase in the probability of incident AF from ‘day employees’, ‘shift but never/rarely night shifts,’ and ‘some night shifts,’ to ‘usual/permanent night shifts.’


The largest risk was related with regular or permanent night shifts [hazard ratio (HR) 1.16, 95 percent confidence interval (CI) 1.02–1.32]. Participants with a length of over 10 years and an average 3–8 nights/month frequency of night shift work exposure had a greater AF risk (HR 1.18, 95 percent CI 0.99–1.40 and HR 1.22, 95 percent CI 1.02–1.45, respectively) when compared to shift workers who never worked nights.

The genetic propensity to AF had no effect on the relationships between present and lifetime night shifts and AF. Current night shifts (HR 1.22, 95 percent CI 1.11–1.35, HR 1.37, 95 percent CI 1.20–1.58, and HR 1.35, 95 percent CI 1.18–1.55, respectively) were significantly associated with a higher risk of incident CHD (HR 1.22, 95 percent CI 1.11–1.35, HR 1.37, 95 percent CI 1.20–1.58, and HR 1.35, 95 percent CI 1.18–1.55, respectively). These links between stroke and heart failure were not statistically significant.


Researchers discovered the following in this large-scale cohort with a 10-year follow-up time: i) In the multivariate-adjusted model, current night shift work was linked to an elevated incidence of AF.

There was a substantial increase in incident AF and CHD risk from ‘day workers’, ‘shift but never/rarely night shifts,’ and ‘some night shifts,’ to ‘usual/permanent night shifts.ii) Shift job exposure for a longer period of time (i.e. 10 years) was linked to an increased incidence of AF.iii)

Night shift work was linked to increased AF and hazards on an average of 3–8 nights per month. iv) Despite low, intermediate, or high genetic risk, there was a positive link between current and lifetime night shift and AF. v) Night shift work was also linked to an increased risk of CHD, but not of stroke or heart failure.

This study had certain drawbacks as well. First, because this is an observational study, the causal association between night shift work and incident AF and CHD cannot be established. Second, there’s the possibility of undiagnosed AF.

According to a recent study, only about one-tenth of AF cases go undiagnosed, and the diagnosis of AF in our study was accurate, as determined by medical records.Third, because the information on lifetime employment was self-reported, it is likely to contain some degree of classification error.

However, as previously stated, the true connection may be nil, and so understated, due to potential exposure misclassification resulting from such misclassifications. Fourth, because the present and lifetime employment information was only examined at the baseline, it is possible that this information will alter over time as the study progresses.


In conclusion, regardless of whether they had a high, intermediate, or low genetic risk, present and lifetime night shift exposure were strongly linked with AF risk in the UKB population. Night shift work raised the risk of CHD, but not stroke or heart failure. Further research is needed to see if reducing the frequency and length of night shift employment could be another way to improve heart health during and after work.

References: European Heart Journal, ehab505, 10 August 20

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