My ldr boyfriend can't stay up past 11 mostly with me, latest 12 yet when I go to sleep his up until 1am?

He says his tired and falling asleep when I'm awake and when I sleep his up until really late, he also used to respond quick to me, like nights were our time to talk since days are busy and now he responds whenever, sometimes hours between, thoughts?
My ldr boyfriend can't stay up past 11 mostly with me, latest 12 yet when I go to sleep his up until 1am?
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