Have you ever had a mosquito in your room or tent at night - buzzing around your head and keeping you awake? It's annoying, right? You try to ignore it but eventually have to get up, turn on a light and squash it or you'll never get any rest. Then the next morning you have to deal with the blood smear on the wall, your hand, lamp shade - wherever you terminated the little bugger.
On Monday night, I woke up just before 4 a.m.. I could hear a helicopter hovering somewhere close to my house. I started to drift back into sleep but after about 10 minutes realized that the helicopter wasn't leaving. It was clearly circling, hovering, then circling again. For more than two hours I'd start to drift off then be wide awake as it buzzed back into my concsiousness. Eventually I fell asleep and it was gone when my alarm went off. No idea what was going on.