The expression "whiles away hours" portrays the act of passing time in a pleasant or relaxing way. However, if we were to come up with antonyms for this phrase, we would require terms to illustrate activities that are unproductive, boring, tedious, or merely a waste of time. Some of those antonyms could be: racing against time, hurrying up to meet deadlines, idling away, frittering away, wasting one's time, killing time, or merely passing time with no purposeful goals.
Some other antonyms that we could potentially consider for "whiles away hours" could be worrying, stressing out, rushing around, struggling with exhaustion, or pushing oneself too hard without taking care of themselves. Overall, the context and tone of the situation should determine the most appropriate antonym for this phrase.