将一篇英语文章翻译成中文，并进行关键词提取，指出文章的主题。


英语文章：The benefits of meditation and mindfulness are well-documented. Studies show that they can reduce stress, improve sleep, and increase overall well-being. Additionally, mindfulness can enhance focus and concentration, while meditation may increase gray matter in the brain.
主题：冥想和正念有益健康。

关键词：冥想，正念，减轻压力，改善睡眠，增强集中力，大脑灰质。