PITTSBURGH, Nov. 20 (UPI) -- Most people with a day job get up early on workdays, but like to sleep late on off days simply because they can. Those disruptions to regular sleeping patterns can increase the risk for developing metabolic diseases such as heart disease and diabetes, according to a new study.
Shift work -- people with irregular work hours or who work something other than day hours -- has been shown in previous studies to have a detrimental effect on health. New research conducted at the University of Pittsburgh shows, however, social jetlag as basic as getting up late may also be bad for health.
Social jetlag refers to a mismatch between a person's socially-imposed sleep schedule and their natural circadian rhythm. Researchers said social jetlag is known to relate to obesity and other cardiovascular conditions, however the link to healthy people is new.
"This is the first study to extend upon that work and 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," said Patricia Wong, a researcher at the University of Pittsburgh, in a press release. "These metabolic changes can contribute to the development of obesity, diabetes and cardiovascular disease."
The researchers worked with 447 people between the ages of 30 and 54, of whom 53 percent were women and 83 percent were white. All the participants were healthy and worked part- or full-time day shifts outside the home for at least 25 hours per week.
The participants wore wristbands to monitor their movement and sleep 24 hours a day, and answered questionnaires about their diet and exercise habits.
The researchers found nearly 85 percent of participants had a later halfway point, called midsleep, in their sleep cycle on free days as compared to work days, while the rest had an earlier midsleep on free days than on work days.
Among the people with larger differences in their sleep schedules from workdays to free days tended to have worse cholesterol profiles, higher fasting insulin levels, higher BMI and were more resistant to insulin than people with more steady sleep schedules throughout the week.
Wong said future studies will need to be larger, and if they show similar results it may indicate that changes to sleep habits could help people lead healthier lives.
"There could be benefits to clinical interventions focused on circadian disturbances, workplace education to help employees and their families make informed decisions about structuring their schedules, and policies to encourage employers to consider these issues," Wong said.