3:00am Noise

Woke up at 3:00am by something. Couldn't tell what it was at first. Seemed to be some shimmery light at the curtains, some strange sound I couldn't place. Groggy shift to the toilet. Open window there. Louder noise. Sudden panic, still couldn't work out what it was. Rhythmical and industrial. Pulsing factory shift. Like a helicopter but not. Had sudden 3:00am inexplicable fear it was a tsunami. Looked out the toilet window. No tsunami. No helicopter either.

Went back to bed. Never found out what that noise was.