Think your email is stressing you out? You’re right! But the problem isn’t necessarily the emails themselves, it’s how you use email.

Researchers recently completed a study to gauge the physical and psychological effects of email. Turns out that email is a mental stressor also affecting our physical well-being. To determine this, they measured blood pressure, heart rate, and cortisol levels—cortisol is a hormone related to stress. The three indicators are signs of elevated stress.

So what makes email stressful? A single email isn’t necessarily any more stressful than a single phone call. It’s the volume of email that makes it more stressful than other forms of communication—and raises blood pressure, heart rate, and cortisol levels.

The types of email causing the most stress are those that interrupt the reader, or those that are irrelevant to the reader, according to the study. This lead researchers to point the finger at multi-tasking as the root cause of the stress, not necessarily the emails.

Over the long term, increased stress levels can lead to the development of serious health issues, like heart problems and high blood pressure. So what about email? One technique doctors recommend is taking email short vacations. So close your laptop, walk away from your desk, and don’t peek at your smartphone to give yourself a little break.