Interesting that Maharishi figured this out back 'in the day'. In the 1960's he was finding people who were not having transcending when they learned to meditate, being the scientist that he was he surveyed about this and found the common denominator was recreational drug use, and hence the '15 day requirement' evolved.
Scientists Still Seek A Reliable DUI Test For Marijuana http://www.npr.org/sections/health-shots/2017/07/30/523004450/scientists-still-seek-a-reliable-dui-test-for-marijuana http://www.npr.org/sections/health-shots/2017/07/30/523004450/scientists-still-seek-a-reliable-dui-test-for-marijuana -JaiGuruYou
