ID this (nonfiction?) crime/psychology essay I read as a child

When I was 7-8-9 years old, in the early '90s, I was a voracious reader and already reading at a high school level, and my parents gave me just about anything to read that they thought I’d find interesting, including stuff I probably shouldn’t have been reading at that age. I was recently thinking about an essay that I read in a magazine around then - possibly Omni, because my parents had a nearly complete collection of it and I found the stuff they wrote about interesting. I’d like to try to find that article, if a copy exists online, and read it now as an adult to see if I get more out of it than I did back then.

The article, which I’m pretty sure was nonfiction, was a feature-length piece about altered states of consciousness. The subject was a man who had shot and killed his wife or girlfriend in the sleeper car of a train, and subsequently had a multi-day standoff with the cops while he was getting no sleep, doing cocaine, slowly dehydrating, and living in this sleeper car with his partner’s rotting corpse. The author set out to try and replicate the experience as closely as possible to see if he could put himself into the same frame of mind as the killer. He had a sleeper car of the same model rigged up with recordings from the standoff so he’d hear the cops outside and see flashing lights just as the killer had done, tried to get as little sleep as possible, snorted either real cocaine or some sort of cocaine analogue, and had the scent of rotting flesh pumped into the cabin to imitate the decaying body. I don’t recall much of his conclusion except him saying that he had to vomit several times and that at one point he had a hallucination of sharks swimming around on the roof of the cabin.

I want to say the title of the article included a pun where the word “night” was substituted with “fright”, like “A Long Day’s Fright” or “Day and Fright” or something like that, but I haven’t had any luck with Google. Does this ring a bell for anyone?