this is a fairly commonly reproduced story

The "falling dream" is a fairly common reproduced story. But "we're going to invent a device that gives you the falling dream" is a big claim and "we're going to give you a heart attack in your sleep by inflicting the falling dream on you" is an even bigger one.

I don’t know if you understand just how much of psychology and medicine in general is literally just self-reports.

Self-reports substantiated with medical data to correlate the symptoms with real physical conditions.

You don't rush a guy with chest pains into the ER, then skip the EKG.

And if the guy with the chest pains says "These pains feel like they've been happening forever", you don't put "forever" on his medical record under "onset of symptoms".

there are absolutely ways to correlate certain states of mind to external measures like FMRI scans

States of mind are very different than conditions of physiology. And even they have their limits. The title card is pure fiction. And trying to tie it back to "a feeling I had when I woke up from a dream" isn't any kind of evidence-based analysis.