I've never experienced this & I've never read or heard a story like it on the board where it's specific behavior tied to a specific time of day.
I tend to lean toward Redatlanta's opinion though - it sounds more like it has to do with the volume of alcohol in her bloodstream by that time of day more than it is the time of day on it's own..... & that she is likely drinking more than you realize so her behavior is reflective of that. Just my $.02!