An alarming new study finds that a large segment of the population is being continually sleep-deprived, and it could have devastating effects on the body that people don’t realize.

Night shift workers are working when most people are asleep, and they usually try to compensate by sleeping while everyone else is working, but they tend to be more sleep-deprived than most anyway. And while the short-term effects of problems with concentration and lack of energy may not seem like a big deal, the long-term effects could result in a huge increase in cardiovascular disease, according to an American Heart Association statement.

Most people realize that disrupting the circadian rhythm is not good for your heart, most people probably don’t realize just how bad it can be for you over the long haul.

For the study, researchers examined 26 healthy people between the ages of 20 and 39 who were asked to restrict their sleep to just five hours for eight days, either at fixed bedtimes or delayed by eight and a half hours on half of the days.

Both groups had an increased heart rate while awake, but it was even higher for those that had a delayed bedtime.

“In humans, as in all mammals, almost all physiological and behavioral processes, in particular the sleep-wake cycle, follow a circadian rhythm that is regulated by an internal clock located in the brain,” Daniela Grimaldi, M.D., Ph.D., lead author and a research assistant professor at Northwestern University in Chicago, said in the statement. “When our sleep-wake and feeding cycles are not in tune with the rhythms dictated by our internal clock, circadian misalignment occurs.

“Our results suggest shift workers, who are chronically exposed to circadian misalignment, might not fully benefit from the restorative cardiovascular effects of nighttime sleep following a shift-work rotation,” he added.