First, there is no "poly lifestyle." Search for "lifestyle" here and you'll find discussion of that notion.
And because there is no such lifestyle, you'll find that polyfolk approach sleeping arrangements in every fashion imaginable. There is no standard poly configuration, so any given tangle can involve three to thirty people--and practical logistical concerns indicate there are no beds built for thirty.
As a personal example, my wife and I sleep in separate beds in separate rooms. My life interest sleeps in her own bed in her own room in a separate house she shares with folks she's not involved with. The other ladies with whom I may get romantically involved with all live in their own places. So, in the tangle in which I am part, ain't nobody literally sleeping with anybody else.
When speaking of various forms of non-monogamy...it ain't poly if you're just fucking around.
While polyamory, open relationships, and swinging are all distinctly different approaches to non-monogamy, they are not mutually exlusive. Folks can, and some do, engage in more than one of them at a time--and it's all good.