"Is there really a difference between indica and sativa or is it all in the head?"
That's a question a Wired viewer asked chemistry professor Amber Wise, PhD in a recent YouTube video.
Her answer is in line with what I always suspected: "The old adage is that indica will make you feel 'in da couch' or relaxed or sleepy, and sativas might make you more creative or more energetic. Recent studies show that there is no molecular correlation between the two, in terms of terpenes and cannabinoid molecules the plant makes. It might just be all in your head."