I think the transition from Lovecraftian "cosmic horror" to modern jump scares is one of the biggest shames of modern cinema. It's easy to copy gore or other ick factor stuff that are part of the classic great horror flicks, but getting the essential creepiness of The Omen, or the alienation of Rosemary's Baby takes talent.
He couldn't sleep for days (I had a nightmare but I could sleep), my father was SO mad.
I thought he could handle it because we'd just watched all the Alien movies and he quite enjoyed them. He saw Aliens first and I suggested we watch the original/rest, he was quite drawn into suspense of the first film which the others have never quite matched in intensity. I guess Event Horizon was a bit too dark and visceral for his tastes.