Antonyms for the phrase "cause to sleep" include words that suggest the opposite effect, such as "wake up," "energize," "stimulate," or "invigorate." While there are several ways to induce sleep, many activities can prevent it, including vigorous physical exercise, excessive caffeine intake, or engaging in stimulating activities such as watching a suspenseful movie. Instead, people may choose to "stay awake," "remain alert," "prevent drowsiness," or "maintain focus and concentration." Overall, antonyms for "cause to sleep" are words that inspire wakefulness and vitality, rather than relaxation and calmness.