Daniel 8:27 (ESV)

27 And I, Daniel, was overcome and lay sick for some days. Then I rose and went about the king’s business, but I was appalled by the vision and did not understand it.

This vision affects Daniel’s health profoundly. He is sick for several days as he imagines how God’s people will be persecuted. He is physically ill on account of what he is shown. After a few days he gets up again. He finds renewed strength and energy in the Lord to again take up his work at the royal court. Inside him there is still the perplexity, the fear of what is going to happen to God’s people. Yet in the Lord he finds the strength to control himself in such a way that the people around him do not notice.