Night nappy
From CntWiki
A night nappy is a nappy specifically designed to last a baby overnight.
Night nappies typically contain more layers of fabric than a nappy to be used during the day. They may also be made of materials that are especially absorbent - bamboo and/or hemp.
Many people recommend a fitted/shaped nappy for overnight, especially if teamed with a fleece or wool wrap. As wool and fleece are breathable materials, they allow some liquid to evaporate meaning that a nappy can feel less damp come morning. However, pocket nappies can also be used, provided the opening in the pocket is large enough to stuff with enough absorbent material to last overnight.