Using your moods to convey what your words don't is lazy communication and eats away at trust.
Great leaders build engagement. Engagement in meetings requires contribution and involvement. Many leaders I work with complain of a lack of engagement from their team members during meetings, despite their best efforts. This is not always about their leadership or their teams’ engagement; often there are other factors at play.
The ability to think quickly is a highly valued skill in the workplace. People who respond to questions off the cuff, who make coherent contributions when called upon (without warning) or who always seem to know the right thing to say in the right moment to say it, are admired by many of us. Especially those of us who need more time to gather our thoughts.