An Earthquake!
There was an earthquake a few hours ago.
And I slept through it. But that does finally explain why I felt so unnerved the whole time this early morning while I struggled to get some sleep. I recall feeling like someone was breathing down my neck the whole time... feel anxious and threatened somehow. I recall feeling like I needed to protect someone from something that couldn't be perceived.

I think I drifted off to sleep around 2:45a.m., a few minutes before the earthquake actually struck.

Gladly, no one seems to have been hurt.