Henry has moved into a similar pattern, but he's 11 months. I'm assuming he's coming to the end of his more puppy phase of needing several long, deep sleeps during the day. He mooches around when we all get up in the morning (6:30, which is much too early for him!). He gets a one hour walk and then his breakfast at 11. He'll have a solid 2 hours sleep in his crate then - I put him in the crate so I can go out then if I need to. When he gets up he is much less active than he used to be as a young pup, just mooching or lying at my feet, and doing the fast asleep / totally awake thing. He used to need another long deep sleep in the afternoon, but he's much less active now in the afternoon so is good with his small naps. He has a 30 minute walk and his dinner between 6 and 7pm and will then be full of beans and a total menace until 8:30 when he goes to bed and sleeps for a solid 10-11 hours.
In total he's probably sleeping 14 hours out of 24. Maybe tot up how much sleep she is getting in total. If she is up from early evening until gone midnight, that sounds like her active time of day (or night!). I'd agree though a vet check is always a good idea.
