A team of Dutch and French cardiologists has found that people who sleep on their side suffer from cardiac arrhythmia more often than people who sleep on their back or stomach, the Telegraaf reported on Thursday.

The team carried out a survey of 500 patients. Of them,  30% experienced an irregular heartbeat while sleeping on their left or right side compared to 19% who sleep on their back or stomach.

The researchers suspect sleeping on your side causes tensile forces to pull on the heart muscle, causing the heart to beat in an irregular pattern. Arrhythmia can affect the pumping function of the heart.

According to cardiologist Lucas Dekker of the Catharina hospital in Eindhoven, it is too early to advise people to stop sleeping on their side. More research needs to be done before recommendations can be made, he told the paper.