Shifts in your sleeping routine, such as getting up early during the week to make it to work on time, could affect your chance of heart disease and diabetes, researchers have found. Even minor changes in your sleeping schedule can be problematic, so you might want to change your alarm routine this weekend to match the one you've set up for the week.
Previous studies of shift workers have already shown that moving our sleeping hours around isn't at all good for us, but these new findings indicate that even slight adjustments can be detrimental to our health.
For the purposes of the study conducted by the University of Pittsburgh, 447 men and women were asked to wear sleep monitoring devices and fill out questionnaires on their exercise and dietary habits. The results showed that nearly 85 percent of the participants had a later 'midsleep point' - the halfway point of the sleep cycle - on their days off, which means that most of them were sleeping in when they weren't needed at the office, as you'd expect.
But the study also found that those who were sleeping in over the weekend and causing a greater misalignment in their sleep schedules tended to have a poorer cholesterol profile, a larger waist circumference, a higher body-mass index, and a greater resistance to insulin than those who got up at the same time every day of the week. This link persisted even when other factors, including calorie intake and physical exercise, were factored out.
"Social jetlag refers to the mismatch between an individual's biological circadian rhythm and their socially imposed sleep schedules," explained one of the researchers, Patricia M. Wong.
"This is the first study to… show that even among healthy, working adults who experience a less extreme range of mismatches in their sleep schedule, social jetlag can contribute to metabolic problems. These metabolic changes can contribute to the development of obesity, diabetes and cardiovascular disease."
Employers and employees should be encouraged to consider the effects of "circadian disturbances", she added, to decide whether a staggered sleeping pattern and a weekend lie-in is really worth the potential health problems and the long-term impact on our body's metabolism.
The study has been published in the Journal of Clinical Endocrinology & Metabolism.
According to the Endocrine Society's Facts and Figures report, more than 29 million adults in the US have diabetes, and 35.1 percent of adults in the US are obese, and it looks like our habit of switching up our sleeping patterns is unlikely to improve those figures.
"If future studies replicate what we found here, then we may need to consider as a society how modern work and social obligations are affecting our sleep and health," says Wong.