Middle-aged shift workers with irregular bedtimes are twice as likely to develop heart disease

Middle aged people who don’t go to bed at the same time every night, including shift workers, are twice as likely to develop heart disease, a new study suggests.

Researchers found that those aged 45 and above who have no regular bedtime, wakeup schedule or get different amounts of sleep each night are significantly more at risk of cardiovascular disease.

The findings, published in the Journal of the American College of Cardiology, revealed that maintaining regular sleep patterns could help prevent heart disease just as physical activity and a healthy diet do.

The five-year study looked at 1,992 men and women aged between 45 and 84 and of them, 38 per cent were white, 28 per cent African American, 22 per cent Hispanic and 12 per cent Chinese American.

Devices on their wrists closely tracked their sleep for seven consecutive days and during the follow up five years later, 111 participants had suffered a heart attack, stroke or died from a heart disease related cause.

Participants with the most irregular sleep duration or timing had more than double the risk of suffering a cardiovascular disease linked event than those who had regular sleep patterns.

Epidemiologist Dr Tianyi Huang, of Brigham and Women’s Hospital in the US, said: ‘We hope that our study will help raise awareness about the potential importance of a regular sleep pattern in improving heart health. It is a new frontier in sleep medicine.’

National Centre on Sleep Disorders Research director Dr Michael Twery said: ‘This study is important because it is among the largest of its kind, and it specifically associates these irregular sleep patterns with an increased risk for cardiovascular disease.’

The association between a lack of a sleeping schedule and heart disease was stronger with ethnic minorities, especially with African Americans than among whites.

This shows that ethnic minorities tend to have a higher risk of sleep disorders.

Previous research has linked irregular sleep schedules to disease-causing abnormalities in body functions like changes in blood sugar and inflammation.

It also associated irregular sleep patterns to harmful metabolic changes linked with obesity, diabetes, and high cholesterol, and they suspect similar processes might also influence cardiovascular disease risk. 

Scientists are still unclear about the exact biological mechanisms behind the sleep irregularity and heart disease link but say it could be down to harmful disturbances in the body’s 24-hour internal clock which controls the sleep-wake cycle.

In future people’s blood biomarkers will be examined to help explain the link between the two factors.