Do birds sleep at night?

I was outside last night around 10:30pm. It was a clear, crisp, cold night and I could see all the stars. I looked up at the sky and said in my mind "I love you Mary".... then I heard the familiar sound I hear in the morning, the "chirp, chirp, chirp" of a cardinal. Believe me, I know what a cardinal sounds like by now. Ask me a year ago and I couldn't guess if my life depended on it. So I listened some more to make sure my mind wasn't playing tricks on me and I heard it again. I must have looked like a crazy girl staring up at the sky and looking all around to see if I could see where the chirp was! It sounded like it was on the roof of my building. I couldn't see anything, but I heard it and heard it again and again. It was the most bizarre feeling. The stars were chirping!

I was thinking to myself ~ "don't birds sleep at night?"

I don't really know, and I don't really care! I got my sign, my sound, my visit and I slept good!
How lucky am I? She is still with me :)!