I've read that 18th century Europeans slept in a position closer to the one we'd associate with sitting up in bed. I don't remember the book, though.

Also, from the Zhuangzi ("Perfect Enjoyment," which is one of the Outer Chapters, so probably around 200 BC):

When Zhuangzi went to Chu, he saw an empty skull, bleached indeed, but still retaining its shape. Tapping it with his horse-switch, he asked it, saying, 'Did you, Sir, in your greed of life, fail in the lessons of reason, and come to this? Or did you do so, in the service of a perishing state, by the punishment of the axe? Or was it through your evil conduct, reflecting disgrace on your parents and on your wife and children? Or was it through your hard endurances of cold and hunger? Or was it that you had completed your term of life?' Having given expression to these questions, he took up the skull, and made a pillow of it when he went to sleep.

At midnight the skull appeared to him in a dream, and said, 'What you said to me was after the fashion of an orator. All your words were about the entanglements of men in their lifetime. There are none of those things after death. Would you like to hear me, Sir, tell you about death?' 'I should,' said Zhuangzi, and the skull resumed: 'In death there are not (the distinctions of) ruler above and minister below. There are none of the phenomena of the four seasons. Tranquil and at ease, our years are those of heaven and earth. No king in his court has greater enjoyment than we have.' Zhuangzi did not believe it, and said, 'If I could get the Ruler of our Destiny to restore your body to life with its bones and flesh and skin, and to give you back your father and mother, your wife and children, and all your village acquaintances, would you wish me to do so?' The skull stared fixedly at him, knitted its brows, and said, 'How should I cast away the enjoyment of my royal court, and undertake again the toils of life among mankind?'

The Classical Chinese here is 枕--literally a pillow or head-rest. So they did exist.