New weird sleep pattern

My sleeping patterns just won't seem to settle into what I want for my twenty-something working life. I am no longer obnoxiously sleeping from sundown to sunup the way I was for a while there, thankfully, but now my sleep patterns have discovered a new weirdness. I am very prone to midday naps from which I wake with something that feels like a dehydration headache, and I consistently hit a hard energy crash around nine or ten at night that threatens to drag me off to sleep. I really, really don't want to fall back into that absurdly early sleep schedule. The weird thing is, if I push through this crash I usually shake off the extreme sleepiness by eleven or midnight, and can stay up comfortably until about one or so, but it's very tough to not let myself just pass out when that heaviness hits. I really dislike being so controlled by my sleep schedule, especially since most days I tend to get a decent seven hours a night. It's so frustrating because I've always been such a healthy person with comfortably regular habits until the last year or so.