Other forms: burning the candle at both ends; burned the candle at both ends; burns the candle at both ends
To burn the candle at both ends is to exhaust oneself by working from early morning until late at night without enough rest. You might have to burn the candle at both ends to finish knitting that sweater in time for your dad's birthday next week!
Imagine having to light a candle to see well enough to work before the sun comes up and then having to light another candle to keep working late at night. That's literally burning the candle at both ends of the day. Today, the phrase is used when a person's hectic life keeps them busy from early in the morning until late at night. When it first appeared in the 17th century, burn the candle at both ends had a different meaning: It referred to wastefulness, recklessly burning a valuable candle too quickly.