People who exhibit a less variable heartbeat when they start worrying are more likely to be highly stressed later on, researchers have found.
Researchers from Concordia University in Canada followed 76 university students during periods of lower stress at the beginning of term and higher stress during the exam period.
Jean-Philippe Gouin and colleagues found that although all students experience similar challenges during finals, only some of them develop significant distress.
With the help of Concordia colleague Sonya Deschenes and Michel Dugas from the Universite du Quebec en Outaouais, Gouin recorded participants' heart rate variability while they were relaxing and while they were thinking about things they tend to worry about most.
They found that those who exhibited a less variable heartbeat when they started worrying were more likely to be highly stressed later on, when faced with finals.
"At rest, a more variable heartbeat is a good thing. It shows that your parasympathetic nervous system is hard at work. That's the system that's responsible for the 'rest-and-digest' state of being - the opposite of 'fight-or-flight'," Gouin said.
"The rest-and-digest phase puts you in a calm state that allows you to conserve and replenish your energy.
"But if your body shows the same reaction when you worry about something that may or may not happen - like failing an exam - then you might be more susceptible to stress.
"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. That's why it's important to have an objective diagnostic tool like this one," Gouin said.