Shift workers with high blood pressure may face higher heart disease risk

People with high blood pressure may be at higher risk for developing cardiovascular disease and diabetes if they work frequent night shifts, new research suggests.

The higher risk was more pronounced among people who also slept too much or too little when they weren’t working, according to the findings published yesterday in the Journal of the American Heart Association.

The new study is the first to investigate the role of shift work in the progression from high blood pressure – a single cardiometabolic condition – to cardiometabolic multimorbidity, defined by the researchers as having high blood pressure in addition to diabetes, coronary heart disease or stroke.

‘Since shift work is increasingly common and hypertension is a leading risk factor for cardiometabolic multimorbidity, it is crucial to clarify the association between shift work and cardiometabolic multimorbidity risks,’ said the study’s senior author Dr Yongping Bai, an associate professor in the department of geriatric medicine at Xiangya Hospital of Central South University in Changsha, China.

The new findings, when added to previous research, suggest “working night shifts can be dangerous to health in both hypertensive individuals and healthy individuals,” Bai said.

Researchers analysed health and employment data for 36,939 participants in the UK Biobank, a large biomedical database of people living in the United Kingdom. Participants, who enrolled in the study between 2006 and 2010, were 40 to 69 years old. They were followed for nearly 12 years on average.

Among people with high blood pressure, usually or always working night shifts was associated with a 16% higher risk of developing diabetes, heart disease or stroke than those who worked during typical daytime work hours. Shift work was defined as any work done during non-standard working hours, or any time between 6pm and 7am. Shift workers make up about 20% of US and European workers, the study said.

To analyse how night shift frequency affected cardiometabolic health, researchers looked at 17,639 study participants who answered questions about lifetime employment. Compared to people who worked day shifts, working an average of one to ten night shifts per month over a lifetime led to a 14% higher risk for developing an additional cardiometabolic condition. The risk was 19% higher among those who worked more than ten night shifts per month.

The risk of developing additional cardiometabolic conditions was higher even if night shift workers got the same seven to eight hours of sleep as daytime workers. The risk was even more pronounced if they slept less than seven hours or more than eight.

Photo by Kai Pilger