Social jet lag, which occurs when the body clock becomes confused by changing sleep patterns - such as weekend lie-ins - may be driving obesity and illness, according to a study.

Researchers from the UK Mammalian Genetics Unit at Medical Research Council, whose work was published in the Journal of Obesity, monitored more than 800 participants and found that those with a greater difference in sleep between free days and work days are more likely to be obese and suffer from obesity-related disease than those with little or no difference in their sleep patterns.

Unlike travel jet lag, which can cause temporary problems with metabolism, social jet lag can occur chronically throughout an individual’s life so is more likely to induce more serious and ongoing consequences for the metabolism, it has been suggested.

“Social jet lag is an under-researched but potentially key contributor to [understanding] why ‘living against our internal clock’ has an impact on our health,” said Dr Michael Parsons, lead author of the study.

“Our research confirms findings from a previous study that connected people with more severe social jet lag to increases in self-reported body mass index (BMI), but this is the first study to suggest this difference in sleeping times can also increase the risk for obesity-related disease,” added Parsons.

The study assessed the height, weight and waist circumference of participants in the clinic, as well as measuring biomarkers for inflammation and diabetes in the blood. These findings were compared with results from a questionnaire, which assessed participants’ sleep duration and their preference in sleep timing, known as ‘chronotype’.

Just a two-hour difference in sleep patterns at the weekend can increase the risk of an elevated BMI and biomarkers for inflammation and diabetes, according to the study.

Reasons for these increases are unknown, but co-author of the paper Dr Terrie Moffitt added: “Further research that determines this association [between social jetlag and obesity] could help inform obesity prevention by influencing policies and practices that contribute to social jetlag, such as work schedules and daylight savings.”

A recent Canadian study explored the possibility of resetting the body’s circadian biological clocks in people with disrupted sleep patterns, such as night shift workers, to prevent health-related illnesses.