candlewaster

from The Century Dictionary.

• noun One who wastes candles; specifically, in contempt or reproach, one who wastes or consumes candles in occupations considered unprofitable or harmful, as dissipation or excessive or late study.
• noun A small part of burnt wick that comes into contact with the melting wax or tallow of a candle and causes it to run.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who consumes candles by being up late for study or dissipation.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun obsolete One who consumes candles by staying up late.