The phrase "hits sack" is a colloquial expression used to indicate that someone is going to bed or getting some sleep. Antonyms of this phrase are words that express the opposite meaning. Some antonyms for "hits sack" are: staying awake, being active, engaging in energetic activities, remaining busy, being alert, working late, partying, or having a night out. These words connote actions that are opposite to retiring to bed. The opposite of "hits sack" can be subjective, depending on the context of the situation. However, whatever the situation may be, antonyms of "hits sack" always convey remaining active, awake, and alert throughout the night.