Our hearts are constantly receiving and pumping out blood, generally heard as a “lub-dub” sound through a stethoscope. The sound occurs when the heart muscle relaxes and refills with blood and when it contracts to send blood back. A healthy heart takes about 0.8 seconds to complete the cycle, resulting in a typical rate of 70 to 75 beats per minute.

Amazingly, heartbeats can synchronize when people are captivated by the same story, sleeping next to each other, or participating in religious rituals such as dhikr in Sufism. Often referred to as “the way of the heart,” the ritual involves deep meditations, ecstatic trances, and sacred melodies and movements, including spinning the body in repetitive circles. Researchers have shown that the Sufis’ quest to unify hearts in celebration of God goes beyond metaphor: Their hearts really do beat as one.