The notion that moderate anxiety can be beneficial goes back at least to 1908, when Harvard psychologists Robert Yerkes and John Dodson posited that arousal (as they called it) enhances performance but only to a point.

WSJ: Anxiety Can Bring Out the Best

David Ford took a lot of brickbats from both the SDLP and the Ulster Unionists, which may betray anxiety that Alliance could eat into their moderate territory.

BBC: NI election Leaders Debate: last word from party heads