Last but not least, our study suffers from limitations. First, the marital quality, work status, and menopausal status were not assessed, all of which have been reported to affect sleep (48–50). Second, the present work compares married individuals to never married individuals which means that the actual sleeping arrangement (bed-sharing vs. individual sleep) remains unknown. This could be seen as impairing comparability with the aforementioned studies on co-sleeping that directly manipulate the sleeping arrangement (13, 14, 33).
