Short answers, pulled from the story.
Meditation can slow the human heart rate to three or four beats per minute and reduce oxygen consumption by up to 20 percent within the first three minutes of practice. This physiological shift reveals that the ancient art of training attention and awareness triggers a profound relaxation response that rivals the body's natural sleep cycle.
The earliest clear references to meditation appear in the middle Upanishads and the Mahabharata, specifically within the Mokshadharma, dating back to the early Buddhist period. The Katha Upanishad describes yoga and meditation as a state where one, having become calm and concentrated, perceives the self within oneself.
Samatha means calm or serenity and steadies and composes the mind, while vipassana means insight and enables one to see, explore, and discern the nature of phenomena. The Theravada tradition stresses the development of samatha and vipassana, postulating over fifty methods for developing mindfulness based on the Satipatthana Sutta.
According to Farias et al. in 2020, the most common adverse effects include narcissistic or sociopathic behavior, depersonalization, altered sense of self, and even mild forms of psychosis including auditory and visual hallucinations. Schlosser et al. reported that of 1,232 regular meditators with at least two months of experience, about a quarter reported having had particularly unpleasant meditation-related experiences.
Meditation has been practiced in Judaism, Christianity, and Islam for thousands years, with the 12th-century monk Guigo II introducing the word meditation from the Latin meditatum as part of a formal stepwise process. In Islam, dhikr is a type of meditation meaning remembering and mentioning God, involving the repetition of the 99 Names of God since the 8th or 9th century.