The antonyms for the word "un-restful" include peaceful, calm, tranquil, serene, relaxed, and composed. These words all suggest an absence of agitation or disturbance, promoting a sense of ease and comfort. For instance, if we feel peaceful, we experience a state of relaxation and well-being, without any worries or tension. Similarly, if we feel calm or tranquil, we can perform our tasks with a clear mind, without being distracted or stressed out. Therefore, these antonyms serve as a reminder to cultivate a peaceful and tranquil state of mind that promotes rest and rejuvenation.