Hi, I think there's nothing wrong with the sentences you wrote. In your sentences, the 'used to' describes your habit (something that you always or usually did, but no longer do) in the past and 'be able to' describes your ability to sleep early, to cook for your parents and to travel a lot. Let's take your first sentence: I used to be able to sleep early.
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Perfect StrangerThe thing I'm driving at is that it seems somewhat weird to me that someone might have been able to sleep early. A sentence like I used to sleep early or I used to go to bed early sounds OK but I used to be able to sleep early doesn't sound good to my ear because I don't really know if we can consider going to bed early as ability... Not like swimming or p