I Haz a Poltergeist?

I was sitting at the computer pulling an all-nighter, and it was past dawn. I was thinking of calling it a day (or night), when I heard a crash of glass from my bathroom. Damn. Expecting a picture off the hook or a shattered toothmug, I went to investigate.

The upper panel of the bathroom window had smashed. Pieces of glass lay all over the floor.

What happened? At first I thought something had broken it from outside – a confused bird, a thrown rock, a blown branch.  But:

• There was nothing out there
• The screen outside the window was untouched and
• It’s a double-paned window, and the external pane was whole.

So the damage had occurred from inside. But:

• I was the only one awake at the time, and wasn’t in the bathroom
• Nothing in the bathroom can accidentally bang into the glass
• The gap under the bathroom door is large enough to prevent a serious pressure differential in the bathroom

So – maybe I have a poltergeist? Or is it a  message from my long-neglected Muse, because the broken window? It looks like a phoenix on its nest.

Then again, it could be thermal shock (though I didn’t notice any serious temperature change) and pareidolia.

I’d be interested in other explanations (preferably scientific, but open to anything).