Many things—both serious and unserious—have kept us up late at night. Worrying about a looming recession. Feeling helpless as the world continues to devolve. Crying over your escapism show turning into a too-personal reliving the last time you’ve gotten your heart irrevocably broken (we’re looking at you, The Summer I Turned Pretty. #teamconrad, you are seen).

While spending a night or two wide awake much later than you normally would is par for the course during the very stressful times that we are in, what happens when you find yourself skipping a full night’s sleep for several days, weeks, or even months on end?

You might be in what experts call a “sleep debt.” And it’s something you should pay attention to and try to course correct ASAP.

Is sleep debt real?

Sleep debt, also known as a sleep deficit, is a very real thing. Jan Stritzke, MD, founding medical director at Lanserhof Sylt, says to think of sleep debt as the cumulative gap between the sleep you need (which experts say should be around seven to nine hours a night) and the sleep you actually get. When you continuously get less sleep than you need, it can wreak havoc on your overall health.

If you happen to stay up late one evening, there’s no need to worry about a sleep debt if you go back to your regular sleep schedule after. A sleep debt happens if you keep staying up late throughout the week, month, and more. “If your body requires eight hours of sleep each night but you consistently get only six, those two missing hours accumulate,” explains Dr. Stritzke. “By Friday, you’ve effectively lost an entire night of rest.”

Tahir Malik, MD, a pulmonary, critical care, and sleep medicine fellow at Mount Sinai, says there are several ways sleep debt affects an individual. If you’re feeling sleepy during the day, have slower reaction times than normal, are extremely irritable, and have measurable changes in your metabolism and stress hormones, you might be experiencing a sleep debt.

The Downsides

When you continuously get less sleep than you need, it can wreak havoc on your overall health. “Even losing just an hour or two each night can have measurable effects on brain performance, mood, and physical health,” says Dr. Stritzke. “Chronic sleep deprivation promotes inflammaging, insulin, and telomere shortening [the shortening of the ends of our chromosomes]. Persistent sleep debt is also considered a hallmark-accelerator of aging.”