rem sleep
"REM sleep is like a toilet,
Flushing proteins from my head.
REM sleep is like a toilet,
Cleans my brain while I'm in bed."
A list of REM sleep associations are in the link...
"REM sleep is like the active rinse-and-spin, occurring every 90 minutes, and each REM cycle gets longer in duration with the longest occurring in the early morning, which is why some remember dreams when the alarm sounds."
"REM sleep is like one large brainstorm, ideas unconstrained by the usual daily distractions and thoughts"
"NREM sleep is like being awake in many respects and it is easily confused with being awake. NREM mentation is what gets left over from a normal brain gone to sleep."

METAMIA is a free database of analogy and metaphor. Anyone can contribute or search. The subject matter can be anything. Science is popular, but poetry is encouraged. The goal is to integrate our fluid muses with the stark literalism of a relational database. Metamia is like a girdle for your muses, a cognitive girdle.