Sleeping requires rest and recuperation in a secure, quiet, and dim environment. Ideal sleeping conditions include a private, ventilated space with a bed and limited distractions. However, sleeping arrangements vary greatly between environments and cultures. Some sleep on mats, in crowded homes, on ships or trains, or in defensive "boxes" within a space. Contemporary bedrooms usually contain a bed positioned along a wall, with additional furniture like storage, tables, and chairs. Proper sleeping arrangements consider privacy, relationships, and space needed for other daily activities.