Weekend lie-ins are bad for your heart, says science

Research into 'social jetlag' claims that irregular sleeping patterns are linked to cardiovascular disease

Bad news for the weekend snoozers, the culture shock you feel when returning to your early morning routine on weekdays may increase your risk of heart disease, Ireland’s biggest killer.

Known as ‘social jetlag,’ which happens when work and social commitments interrupt your natural sleep cycle, the effects of the phenomenon have been investigated by a team at the University of Arizona in Tucson.

“A lot of people will be waking up at 7am on weekdays, but going to be later and sleeping in on the weekends to compensate,” says the study leader Sierra Forbush.

To research the detrimental effects of social jetlag, nearly 1,000 volunteers living in Pennsylvania had their sleeping habits analysed. To evaluate the toll changing their bed and rising times had on their health, Forbush’s team compared the midpoints between when the participants said they went to bed and got up on weekdays and weekends.

Adjusting for those who suffered from insomnia, the team found that for every hour of social jetlag, there was an 11% increase that that person would suffer from cardiovascular disease. Furthermore, social jetlag was also connected to irritable mood and greater levels of sleepiness and fatigue.

People who managed their sleep cycle more rigidly, experiencing even just an hour of social jetlag, were 22% more likely to rate their health as good rather excellent and 28% more likely to rate it as fair or poor.

“Physicians often tell people to think about their diet and exercise, but I think this offers an additional preventative strategy,” says Forbush, who presented her findings at a sleep conference in Boston.

“It’s not just about getting enough sleep, but getting regular sleep; ideally, you want to be going to bed and waking up at the same time every day of the week.”

This University of Arizona study is not the first piece of academic research to link social jetlag to a worsened quality of health. The endocrine system, governing the body’s hormone regulation, can develop irregular habits when exposed to people to a shifting Circadian Rhythm, the natural body clock.

“There are studies indicating that chronotype – a person’s biological inclination towards morning or evening preference – may influence risk of cardiovascular disease, and evening types may be more at risk,” says Tami Martino, of the University of Guelph in Ontario, Canada.