Health & Fitness

Irregular sleep patterns increase heart disease risk


Women are more likely than men to be affected by unhealthy sleep. FILE PHOTO \ NMG

Sleep is something most people take for granted. They only go to bed once they are done with their night chores or when fatigue finally sets in and their eyelids start drooping.

While this may appear as a seemingly harmless habit, health experts note that it is predisposing people to adverse health effects, especially as they grow older.

They recommend that people think meticulously about their sleeping habits and schedule sleeping times and durations appropriately.

A new study published in the Journal of the American College of Cardiology has found that older adults with irregular sleep patterns have a higher risk of developing a cardiovascular illness.

Cardiovascular disease (CVD) is a general term used to describe a range of ailments that affect the heart and blood vessels.

They include heart failure, abnormal heart rhythm (arrhythmia), heart valve problems, heart infections, congenital heart defects and narrowing of blood vessels. These conditions can lead to adverse health effects like heart attacks and strokes.

The research findings revealed that adults with irregular bedtime and wake-up schedules, or those that get different amounts of sleep each night are nearly twice as likely to develop cardiovascular disease compared to those with more regular sleep patterns.

According to the researchers, the results of the new study suggest that an irregular sleep pattern may be a novel and independent risk factor for cardiovascular disease.

It also shows that maintaining regular sleep patterns could help prevent heart disease just as other lifestyle measures such as physical activity and healthy diets.

“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,” said Tianyi Huang, the lead author of the study and an epidemiologist with the Channing Division of Network Medicine at Brigham and Women’s Hospital in Boston.

The researchers noted that the high cardiovascular disease risk could be due to the harmful disturbances that irregular sleep patterns have on the body’s circadian rhythm (a 24-hour internal body clock which controls the sleep-wake cycle).

Previous studies have linked insufficient amounts of sleep to a higher risk of obesity, diabetes and heart disease. This is among the reasons doctors emphasise the importance of getting seven to eight hours of sleep per night.

Although researchers have suspected that high day-to-day variability in sleep duration and timing might also have negative effects on heart health, the effects remained unclear.

The novel study, which was conducted over five years, is believed to be the first to fill the knowledge gap and conclusively link sleep irregularity to the development of the cardiovascular disease.

“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,” said Michael Twery, the director of the US National Heart, Lung and Blood Institute (NHLBI) Centre on Sleep Disorders Research.

During the current study, the researchers followed 1,992 men and women from different US communities, aged between 45 and 84, who did not have cardiovascular disease at the start of the study.

Of the participants, about 38 per cent were white, 28 per cent African American, 22 per cent Hispanic, and 12 per cent Chinese American. They were followed for about five years after having a sleep examination.

To measure sleep irregularity, the participants wore actigraph devices on their wrists. The devices resemble smartwatches that are designed to specifically measure whether a person is active or at rest. This correlates to wakefulness and sleep.

Thanks to technology, the researchers were able to closely track the participants’ sleep and wake activity for seven consecutive days, including weekends.

Besides, the research participants were subjected to a comprehensive sleep test known as polysomnography at the beginning of the study. They were also subjected to a questionnaire-based sleep assessment.

During the five-year follow-up period, 111 participants suffered from effects of cardiovascular disease such as heart attacks and strokes. Some ended up dying from the conditions.

According to the researchers, participants with the most irregular sleep duration or timing had more than double the risk of developing a CVD over the follow-up period compared to those with the most regular sleep patterns.

They noted that although past studies suggest that women are more likely than men to be affected by unhealthy sleep, the current study did not find significant gender differences.

According to the researchers, a better understanding of the root causes could lead to new medicinal or technological interventions that could help people better regulate their sleep patterns, such as wearing devices or using specialised mobile apps designed to reduce irregular sleep.

In addition to regular sleep patterns, people can reduce their cardiovascular disease risk through cessation of tobacco use, reduction of salt in diets, high intake of fruits and vegetables, regular physical activity and avoiding harmful use of alcohol.

Moreover, drug treatment of diabetes, hypertension and high blood lipids may be necessary to forestall the disease risk and prevent heart attacks and strokes.

Often, the cardiovascular disease presents with no symptoms. A heart attack or stroke may be the first warning of an underlying condition.

Symptoms of a heart attack include pain or discomfort in the centre of the chest, left shoulder, arms, elbows, jaw or back. The most common symptom of a stroke is sudden weakness of the face, arm or leg. This mostly happens on one side of the body.