One more thing, we only have BW to say she was hungover. I have a hard time believing that someone would climb on a bike early in the day while headachey and nauseous and ride four miles. Not saying young people do not do things like that, I just think it would be rough.
not trying to sleuth him, just wondering.
I think there were plenty of other people besides BW who could (and probably did) confirm for LE that she wasn't feeling well/was hungover.
She had been out with her sister the night before. Presuming her sister was staying at the family home, I'm sure she and her sister discussed it the next day if Mickey wasn't feeling well.
And remember that the night she disappeared, she and BW were with their group of friends at Artmosphere. Surely she at least made an offhand comment about not feeling well, or told someone when asked why she wasn't having a drink that night.
I agree that during a bad hangover a bike ride wouldn't be a preferred activity for me. IMHO, her hangover probably just left her feeling under the weather; not awful. Combine that with knowing she had to go to her brother's graduation the next day and she may have felt well enough to be out and about but bad enough to mention it to her friends and refrain from drinking.