"Bons nuit" is a French phrase that translates to "goodnight" in English. There are numerous synonym options to use instead of "bons nuit." Some of the common ones include phrases such as "sweet dreams," "rest well," "sleep tight," and "pleasant dreams." Alternatively, one can use short phrases such as "goodbye till morning" or even "nighty night," which is a cute and casual way to wish someone a good night's rest. Whether you choose a traditional or a more creative option, the underlying sentiment is the same. The goal is to convey a warm and caring message to the recipient that will help them have a peaceful and restful night.