When people sleep on their left side, they may notice that their heartbeat feels louder or stronger. This is a common experience and is not usually a cause for concern, according to health experts.
The sensation occurs because of the way the heart is positioned in the chest. The lower tip of the heart, called the apex, consists mostly of the left ventricle, which is responsible for pumping oxygenated blood throughout the body. The apex angles downward and sits slightly to the left of center in the chest. When lying on your back or right side, this position does not change significantly. However, sleeping on your left side causes gravity to move the apex closer to the chest wall.
Additionally, as you lie still and quiet during sleep, it becomes easier to notice these physical sensations. The rib cage can also compress slightly under body weight against a mattress, further bringing the heart closer to the surface and making its beating more noticeable.
“In healthy adults, sleeping position hasn’t been found to have an adverse effect on the heart or on the efficiency of its pumping action,” states UCLA Health Sciences Media Relations.
However, research suggests that people with certain heart conditions such as atrial fibrillation may be more sensitive to changes in sleeping position. Atrial fibrillation is characterized by irregular and often rapid heart rhythms. While sleeping position does not cause arrhythmias like atrial fibrillation, individuals with these conditions might notice symptoms more readily when lying on their left side.
Experts emphasize that unless there are additional symptoms—such as persistent chest pain or pressure (especially if it spreads), unusual shortness of breath or difficulty breathing, dizziness or fainting—there is typically no need for concern about feeling a stronger heartbeat while lying on your left side. Anyone experiencing those warning signs should seek medical attention immediately.
Questions about health concerns can be sent to [email protected] or mailed to Ask the Doctors at UCLA Health Sciences Media Relations in Los Angeles.
