You cannot burn the candle at both ends.
蜡烛不能两头烧。/勿过分消耗体力。
Some students don’t study until a couple of days before an exam. They have to stay up late cramming. As can be expected, they don’t usually do well on the exam because of a lack of sleep. What’s even worse, their health could thus be ruined. Remember: “You cannot burn the candle at both ends.”
有些学生直到考前几天才念书。他们得熬夜临时抱佛脚。可以预期的是,他们往往因睡眠不足而考不好。更糟的是,他们的健康可能因此而搞坏。记住:“蜡烛不能两头烧。”