Daybeds may also incorporate a trundle unit as well. Trundle units allow for an extra mattress to be stored underneath, to be pulled out for extra sleeping space when needed. You can choose a pop-up trundle unit, where the extra mattress can be rolled and elevated to the same height of the daybed, converting it into a king-sized sleeping area. The other option for trundle units is a pull-out, where the extra mattress is rolled out on wheels or a glider. However, these do not elevate to the daybeds height, forcing you to sleep much lower to the ground.