Of the 15 songs tested by market research firm Mindlab International, "Weightless" was found to induce the greatest relaxation in study participants, according to The Daily Mail. Other songs the researchers tested were chosen by surveying people about the music they found relaxing and included tracks from artists like Enya, Coldplay, Adele, and Mozart.
It's not entirely surprising that the song was found to be so relaxing - it was intentionally created for a spa with the help of therapeutic sound therapist and Founder of the British Academy of Sound Therapy, Lyz Cooper.
"The sound works from the point of view of sustained tones, which really help a person feel safe," she said.
The tempo starts at 60 beats per minute and gradually decreases to 50 beats per minute.
Another study by researchers from BMS College of Engineering in Bangalore, Malaysia, saw subjects report a dramatic reduction in feelings of stress and an increased sense of physical relaxation when they listened to music that played around 60 beats per minute. In classical music terms, you would refer this as "larghetto," which translates to not very fast or somewhat slowly.
"While listening, your heart rate gradually comes to match that beat," Cooper told The Daily Mail.
Marconi Union's ambient tune, which combines piano and guitars with atmospheric and synthetic sounds, is eight minutes long, Cooper says, because it takes about five minutes for your body to synchronize with a rhythm, a process known as entrainment.
The song was also designed not to have a repeating melody so that the brain does not try to predict what will come next, which is said to help induce a deeper sense of relaxation. It's apparently so effective that people are advised against listening to it while they drive.
Instead, Cooper says, "''Weightless' is ideal for putting on at the end of a stressful day and unwinding."