You're right... I was citing some "knowledge" I acquired almost a decade ago, assertions which were poorly sourced. Googling this now doesn't lead me to any reliable citations. Hah, if it is indeed true, we've made every human being a felon. DMT is a Schedule I substance in the United States, so if we're naturally producing it in our bodies, even if in minute quantities... welp, see you in prison, buddy!I tried searching for some evidence for this, but I was not able to find anything reliable.
People were discussing if its true that DMT is produced endogenously, a review of the literature suggests that it is true - PDF
I have also read (somewhere) that DMT is produced in higher concentrations when a person is close to death. While nobody can really explain why this happens, it is interesting. Specially when you keep in mind that LSD and Psilocybin are used to treat death anxiety in people with terminal diseases...