Nightmares & the likes

I was sleeping earlier and had this massive nightmare that literally shocked me awake. I dont really remember the dream in depth but i do remember it preyed on my worst fears using the things i like most which made me think more about the nature of nightmares. Theres a lot of causes for nightmares and i admit i am under a few of the reasons as to why they happen. But it feels like a cruel prank on ourselves for nightmares to even be a thing. Imagine being anxious and using sleep to calm down yet your brain gives you a nightmare... thats just cruel.