If you wake up during the night, you should identify and eliminate possible reasons, esp. if you appear to wake up tired. The reasons and the way to diagnose them are too many to describe in a short answer. However, you should always start from the simplest one: problem with the circadian rhythm.

In simple words, the timing of your sleep may be wrong. Partitioning of sleep is a typical symptom of going to sleep too late or going to sleep too early. If you are healthy, in free running sleep, you will rarely wake up during the night; and if you do, the reasons will be quite obvious such as: stress, noise, thirst, coldness, full bladder, etc.

However, if you attempt to regulate the timing of your sleep, the partitioning of sleep (i.e. interrupted sleep) will be a frequent result. It is possible to push your sleep slightly ahead or back (e.g. 15-25 minutes per day) without this negative outcome.
However, once you try to push too hard , you will likely wake up early in the night, i.e. before your circadian low ensures deep sleep.

On the other hand, if you push forward (i.e. going to sleep later and later), your circadian low will end before you complete your sleep cycle. As a result, you will often wake up earlier than expected. If this waking up happens very early (when you push ahead very hard), you will be tired enough to fall asleep again.

In other words, whichever way you push your sleep, it will not be properly aligned with your circadian rhythm. You will then wake up early or late in the sleep cycle depending on at which end the misalignment occurs.