Question

Is there a proper way to inform a neighbor that his/her late-night amorous activities are preventing you from getting sleep? I've consulted my copy of The Amy Vanderbilt Complete Book of Etiquette (got it free along with a box of other books by helping out at a book sale) and found nothing on point. Were this anything other than an hour of constant the squeaky-squeaky of their bed, I would have no problem knocking on said neighbor's door and politely requesting that the loud noise stop. However, the nature of the noise presents a whole mess of problems. I would just ignore it, but it's really loud and has woken me up out of a decent slumber the past two nights - and after 1 AM, no less. At least it's just the noise of a bad mattress that I hear and not the other various sounds that can accompany such activities. I've contemplated leaving a note on the door to the effect of "Just so you know: your bed squeaks very loudly." Any other suggestions?