I've heard something similar too. Like a low resonance that wakes you up in the night and you are 100% awake. I've seen lights in the sky and even videod them (on DV tape) so not sure how I digitise them.

Very odd, very strange and my Mrs doesn't hear it but did see the lights after I got her out of bed at 3.40am to confirm my sanity.

Some very weird shit happening at the moment.