The drug improved mental alertness.

这种药物提高了大脑的灵敏度。

《柯林斯英汉双解大词典》

Studies regularly show that eating breakfast improves mood, mental alertness, concentration, and memory.

长期的研究表明吃早饭能够改善情绪，保持思维敏捷，注意力集中以及良好的记忆力。

youdao

Being young has universal appeal and today people are searching for the qualities that youth comprises good health, mental alertness, physical attractiveness, and vigor - in a word, fitness.

年轻具有普遍吸引力，今天人们在搜寻着构成年轻的要素：好的身体，精力充沛、身体的外在魅力，朝气蓬勃——一句话，健康。

youdao

The differences were linked to the mental alertness required to switch between languages, which could develop skills useful in other types of thinking.

BBC: Bilingual children 'better at problem-solving skills'