If you have a steady heartbeat when you worry about something that may or may not happen, you might be more susceptible to stress, says a study.

According to new research from Concordia University, those who exhibit a less variable heartbeat when they started worrying were more likely to be highly stressed later on.

“At rest, a more variable heartbeat is a good thing. It shows that your parasympathetic nervous system is hard at work. That is the system that is responsible for the ‘rest-and-digest’ state of being – the opposite of ‘fight-or-flight’,” explained psychology professor Jean-Philippe Gouin.

The rest-and-digest phase puts you in a calm state that allows you to conserve and replenish your energy.

During the study, Gouin followed 76 university students during periods of lower stress at the beginning of term and higher stress during the exam period.

He found that, although all students experience similar challenges during finals, only some of them develop significant distress.

Researchers recorded participants’ heart rate variability while they were relaxing and while they were thinking about things they tend to worry about most.

They also tracked participants’ moods at low stress and high stress periods during term.

“By pinpointing those in the general population who are most vulnerable to stress, we can intervene before they hit the breaking point – and hopefully prevent the negative consequences of stress by doing so,” Gouin added.

The paper was published in the journal Stress.