I'm not sure what you're trying to convey. If you'd like a sentence with the same meaning as "I woke up at 10", you can say:
I slept until 10.
If you are trying to say that you began sleeping at 10, you could use either:
I went to sleep at 10.
I went to bed at 10.
If you are trying to say that at 10, you were asleep (not awake), you could use either:
I was sleeping at 10.
I was asleep at 10.