Why I shouldn't study psychology late at night

I know how you sleep
and I recognize you as I read chapter five of this stupid textbook.
As I turn the pages I remember how you shift and settle
before that quick drop-off into unconsciousness.
Stage one used to be a surprise, now I barely startle
at the twitches of your relaxing muscles,
the sudden mumbles as incoherent as this vocabulary.
Stage two is when your steady breathing fills the room,
when you're spun along on spindles, held fast by delta waves.
I've studied you better than my notes, I see you in the words.
Stages three and four--I hadn't known the name of that heavy,
immovable time of night, now you are my mnemonic device.
It is not so safe on the inside as it seems on the outside,
an I wonder what happens in the confines of your brain
as you lie so still.
There is nothing in this text about the things you see while
I am awake and watching you.

Strange that the rhythms of your sleep cycle are as familiar as my own-
frantically I turn to the glossary,
flip through the index,
but there is nothing in this book that explains how I love you,
much less why.