She follows him, retrieving her bottle of water and draining it before going quickly to galley to get another – and, after a second's thought, another bottle for him, too.

The co-pilot's seat is small, but she can curl into it without too much trouble, taking the blanket from him and tugging it over her legs, propping the pillow behind her head. This way, even if she does fall asleep, he'll be the first thing she sees when she opens her eyes. It might not stop the nightmares, but it should help with the waking.