The FA in question, who did not apologize but instead tried to defend her action, did suggest that the pax could have told her ahead of time. I agree that a sticker or other proactive communication makes sense for long-haul red-eyes (for example, they ask on US-SYD-US if you want to be woken up for breakfast, at least in F), but for a short flight in late afternoon, I can see how it wouldn't be obvious.

I'd think there would be a policy for the FA's so it's consistent, though. I guess I should post this in "ask a FA", whether there is or not. If there's no guidance and it's up to the individual FA, then I blame UA. There should not only be a policy, it should be known to passengers so they know what to expect and what they need to do in terms of notification.

Personally, I think sleep is 100% sacred, and no one should ever be awakened in a premium cabin unless they specifically requested it. Those of us who are on the road a lot usually have trouble getting enough in the first place.