It's better for your mental faculties than 20 minutes of aerobic exercise on the treadmill; in fact, sweating it out at the gym doesn't make any difference to your memory or ability to focus.
Researchers from the University of Illinois tested the two exercise systems on a group of 30 young, female undergraduates, and then assessed their mental capabilities afterwards.
They started with a 20-minute hatha yoga session, which included breathing, standing and floor-based positions. After that, they jogged or walked on a treadmill for 20 minutes, with the aim of maintaining 60 to 70 per cent of maximum heart rate throughout the session.
Their memory, reaction times and cognitive ability were all improved after the yoga session, while no differences were recorded after the aerobic exercise.
(Source: Journal of Physical Activity & Health, 2013; 10: 488-95).