Mantras, which are prolonged repetitive verbal utterances, are one of the most universal and long established mental practices in human culture. It has a powerful emotional and cognitive impact
Research done to see its effect after isolating it from wider context and spiritual orientations have shown that the repetitive speech on its own was sufficient to reduce significantly intrinsic thought processes compared to rest.
In mind it triggers global inhibition to produce psychological calming effect.
Berkovich-Ohana A, Wilf M, Kahana R, Arieli A, Malach R. Repetitive speech elicits widespread deactivation in the human cortex: the “Mantra” effect? .