Competing time cues wreak havoc with our bodies, reports NPR.

So consider what happens, for instance, if we eat late or in the middle of the night. The master clock — which is set by the light-dark cycle — is cueing all other clocks in the body that it’s night. Time to rest.

“The clock in the brain is sending signals saying: Do not eat, do not eat!” says Turek.

But when we override this signal and eat anyway, the clock in the pancreas, for instance, has to start releasing insulin to deal with the meal. And, research suggests, this late-night munching may start to reset the clock in the organ. The result? Competing time cues.