The Reef by Edith Wharton

Almost as soon as the train left Calais her head had dropped back into the corner, and she had fallen asleep.

Sitting opposite, in the compartment from which he had contrived to have other travellers excluded, Darrow looked at her curiously. He had never seen a face that changed so quickly. A moment since it had danced like a field of daisies in a summer breeze; now, under the pallid oscillating light of the lamp overhead, it wore the hard stamp of experience, as of a soft thing chilled into shape before its curves had rounded: and it moved him to see that care already stole upon her when she slept.