Interesting one this, though I'll admit ghosts aren't really my area - I'm more of a UFO man myself. But I've noticed something similar when I've been out doing late night sky watches around that time. There's definitely something about 3am that feels different, quieter in a way that's almost too quiet if that makes sense.
What I'd want to know is whether anyone has actually tracked this properly over time, like kept a log with dates and times rather than just going off memory. Because I wonder if theres a pattern linked to something mundane like temperature drops or local wildlife before people jump to paranormal explanations. Has anyone ruled that stuff out?
Also curious whether this is reported more in old buildings or does it happen in fairly modern ones too?