If you go to bed and then wake up at the same time every night you could have terminal insomnia which causes you to wake up in the middle up the night or even at 3:00 AM
If waking up in the middle of the night causes you to have a disruption of your sleep you should speak with your doctor or take some sleeping medication.
Some people will wake up in the middle of the night at the same time at night to go to the bathroom because they need to pee which is normal.
But if you're just waking up in the middle of the night then it's likely just insomnia.
If you can get back to sleep soon after waking up then there's not much to worry about.
But if you wake up in the middle of the night at the same time each night then can't go back to sleep it becomes a problem.