Murphy's Law of Snoring

"Your slumber-partner will snooze silently during periods that you're up and away from the boudoir, but then he will totally 'saw logs' whenever you're actually cohabitating with him --- and wanting to get some shut-eye --- in the same bed."

Perhaps many instances of Murphy's Law of Snoring stem from the snorer's needing more space to "spread out", which he would have whenever he has the whole bed to himself; being more cramped can restrict air-passages and so on..