清醒 (qīng xǐng): claire tête

At three in the morning, he drank a cup of strong coffee, and his mind immediately became much clearer, so he continued to work with concentration.

The doctor told him to stay awake after surgery and not to fall asleep right away, so they could observe whether there were any adverse reactions.

At the lively celebration party, he remained clear-headed and did not let the praise go to his head; he seriously thought about the next step of the plan.

Upon hearing the sudden news, she was a bit flustered at first, but soon came to her senses and calmly dealt with the problem.