I know this is probably a common topic. For me, I’m not sure if it’s a “trope” or just totally misinformed writing, but it’s how many authors approach alcoholism. Some examples are Girl on the Train and The House Across the Lake, among HUNDREDS. If anyone else here has struggled with alcoholism, you know it’s not just "i woke up after downing an entire bottle of whiskey but was able to shower, down a cup of coffee, and solve a murder. "
It worked well with the book >!The Murder of Roger Ackroyd!< since at that point, it was a firmly established rule of the mystery genre that the narrator couldn’t be the killer of the story. In fact, >!Agatha Christie!< was a member of the Detection Club which practiced the Knox Decalogue of mystery rules, one of which was “The Narrator can’t be the killer”.
Also, there was an episode of the TV series McDonald & Dodds that does this rather well and makes perfect sense in context. >!The “Victim” was a social media influencer who wanted to quit but was being stalked by an obsessive fan so made use of an upcoming plastic surgery procedure to switch places with the fan to make her think she could get a procedure for free, instead using it as a means of murdering the fan and faking her own death as she fled the country.!<
That book did it so well. I was convinced up until the end that the murderer was >!Dr Sheppard’s sister!<