Mindfulness has gone mainstream, with the top 10 smartphone apps for meditation cumulatively reaching some 300 million downloads worldwide. The practice, research suggests, reduces stress and anxiety and improves mood and emotional regulation. 

Advanced meditation may offer even greater benefits — potentially leading to transcendent states of mind and awareness, according to scientists at the Massachusetts General Hospital Meditation Research Program who are pioneering studies in the field.

Matthew Sacchet, the program’s director and an associate professor in the Harvard Medical School Department of Psychiatry, helped us develop the following quiz on what scientists are only beginning to learn about these deeper practices.