Why does my cat always meow at night?
01Cats can't sleep and are full of energy. Many cats like to sleep during the day and be active at night. When they can't sleep at night, they really want to get their owner's attention and will meow to wake them up so that their owner can play with them.
02
They've spotted something. Cats have very keen hearing, vision, and senses. If they see something outside the window or door, they'll immediately become alert and try to scare it away with their voices. 
03
It's estrus. If a cat's meows are very hoarse at night, like a child crying, it's likely in heat, especially female cats, who often meow all night long during this time.
04
Cats are telling their owners what they lack by not eating or drinking enough. Generally, smarter cats will proactively go to their food or water bowls to let their owners know.
05
Cats are not feeling well. During seasonal changes, when temperatures fluctuate significantly, cats may exhibit cold-like symptoms. If your cat is meowing constantly and appearing lethargic, you should consider whether your cat is sick.