Help me identify an episode of a horror show.
 

I only have a few details. I believe the show, either a one off or part of a horror anthology, was from the 90s. It may have been on a premium channel (HBO, Showtime, etc).

I don't remember the full plot. What I do remember is some kind of psychologicial experiment, on or with the help of a young woman. When she would be placed in a hallucinagenic or dream like state, she would be vulnerable to a dead serial killer. The dead serial killer was still interested in being a bad dude from beyond the grave.

What stands out most in my memory is the glitchy/twich visual effect used for the serial killer. It was that 90s, sped up, supernatural look--and I think the fx make up was similar or a precursor to the style of a movie like 13 Ghosts or something. I think at the end of the episode, the scientist or researcher ended up sacraficing himself for the girl, but I could be wrong.

Things I don't know: stars names; names of the anthology it was produced in (if it was at all); director; plot details; i.e., anything helpful or specific.

So there you go. Super vague details. ¯\_(ツ)_/¯ It may have been a British show. Maybe American--sorry, I saw it once, a long time ago, and I was young. Help me out!