Hi. I know the feeling! I telephone my husband to tell him what a crappy day I'm having, and then when he gets home in the evening I have perked up and it is kind of confusing to him! Doctors have told me that happens with some people.
I think it's a circadian rhythm shift. I'm the same way (though I don't perk up till 9:00 p.m.) I've been a night owl all my life, it's just more noticeable now with the fibro/cfs because I have my usual daytime torpor plus the fibro fog and fatigue.
Ya I know what you mean too. I come around starting at about 9ish. When I wake up though I am a zombie and I can't do anything. By bedtime I am wound for sound and it is hard to go to sleep and I drive my boyfriend crazy because he wants to sleep.