Sleeping late on days-off—and other sleep-time adjustments—are linked to metabolic problems, including insulin resistance and a higher body mass index, according to a new study published in the Journal of Clinical Endocrinology & Metabolism. The finding suggests that regular sleep shifts could rouse long-term health problems such as cardiovascular disease and diabetes, the authors conclude.

Though other research has connected sleep disruptions to poor health, the new study is the first to specifically link shifts in dozing times to metabolic problems. Those problems were independent of other factors such as sleep disorders, smoking, and socioeconomic status.

Such weekly sleep changes may alone cause trouble by throwing off the body’s internal clocks, putting metabolic cycles out of sync with other circadian rhythms, the authors speculate. For instance, fat accumulation in tissues, food absorption in the gut, and insulin secretion in the pancreas and liver all show tissue-specific circadian rhythms, the authors note.