One night, sitting at the dinner table, JD mentioned how tired he was, and that he didn't sleep very well. Sonora asked Daddy why he didn't sleep, and he replied, "Sometimes I am just up at night." She cocked her head and said, "I guess that means you are nocturnal."
You used it correctly in a sentence, girl, now spell it!
Part Jane Goodall, part Mary Poppins, part Miss Hannigan. Not a significant source of Martha Stewart.