Nightmares are something Jean-Luc is very familiar with. And did he know that Eric was experiencing them, he might attempt to speak with him about them. He had learned from Counselor Troi, after all, that speaking of them could help to ease your mind toward them. And while he was by no means a counselor of the caliber that she was, he was always open to helping others were they to show a need for it.
At the moment though, it's his curiosity that is piqued by the others response. He nods in greeting and opts to introduce himself. "Captain Jean-Luc Picard. May I sit with you?"