Maybe http://www.theskepticsguide.org/podcast/sgu/530

https://www.sgutranscripts.org/wiki/SGU_Episode_530

?

hey, that's not bad; didn't even expect SGU had such detailed transcripts.

But actually looking for it now, the particular study I had in mind seems to be from a science or fiction segment from this episode:

http://media.libsyn.com/media/skepticsguide/skepticast2014-1...

Interesting to see how Steve's assesment of modafinil evolved between the two episodes

Thank you so much for your time. I was really curious.