A co-sleeping bassinet is a baby bed that attaches to the side of an adult bed, allowing baby to remain close to the parents at night without actually being in the adult bed. Co-sleeping bassinets resemble a crib with one of the side rails taken off. The open end is placed next to the adult bed, with the co-sleeping bassinet mattress and adult bed mattress at the same level, so that a parent can easily reach the baby during the night for breastfeeding or other care.
Co-sleeping bassinets allow babies the benefits of sleeping near a parent, but ease some parents' fear of rolling over on the child. Some parents choose to modify an existing crib to a co-sleeping bassinet by removing one side rail and pushing the crib up against the adult bed. Care should be taken in using a crib as a modified co-sleeping bassinet to be sure a gap or height difference doesn't form between the two mattresses.
The term "cosleepers" is also used to describe parents and children who share the same bed.