A trundle bed is a type of bed that is built on casters so that it can be slid underneath another bed or piece of furniture. Usually, it's sold along with the main bed as part of a set, to ensure that the trundle portion will fit underneath and be properly supported. This setup can be an excellent space saving solution as well as a convenient way to have a guest bed available when needed, but out of the way when it's not.
Often, a trundle bed assembly is used as a day bed. The primary bed resembles a small couch and can be used as a piece of living room or lounging furniture. When the bed function is needed, bedding can be moved around to create a bed, and when an extra place to sleep is necessary, the trundle portion can be pulled out. In some cases, this roll-out part is designed to pop up to the same height as the day bed, creating a double bed for guests. Some assemblies are also designed with drawers to hold bedding and pillows.
Many parents use this type of bed in children's rooms, to provide a bed for a sleepover guest. It can also be useful when multiple children share the same room, allowing them to be active during the day and pull the bed out at night. Most beds are light enough for a child to move without the assistance of an adult, meaning that he or she can make the bed and put it away in the morning.
In most cases, because a trundle bed is designed to fit into a small space, the mattress will be very thin. This can be uncomfortable for older guests or people with back problems, who often require more support while they sleep. If this is expected to be an issue, one with a thicker mattress can be purchased, although it will force the height of the primary bed to be higher.
Trundle beds can be made from a wide variety of materials to complement many interior decorating schemes. Common trundle/daybed assemblies include ones carved from wood, made from cast iron, or upholstered in fabric to resemble traditional couches. The price for a set can vary widely, depending on what type of materials are used and the quality of the mattresses.