A sleepweaver is a ter'angreal that provides the user access to Tel'aran'rhiod. The most well known sleepweaver in the series was given to Egwene al'Vere by Verin Mathwin and was studied by Corianin Nedeal, the last Dreamer of the White Tower before Egwene. Other sleepweavers still in existence come in the shape of a striped stone ring, an iron disc, and an amber plaque of a sleeping woman.
The purpose of all sleepweavers is to allow the user to enter the World of Dreams while sleeping. They differ by shape, material, and requirements for usage (some require channeling of Spirit, some require no channeling). Sleepweavers were apparently made during the Age of Legends to be used as practice for dreamwalking, and as such, most will cause the user to appear misty and transparent. Copies of sleepweavers made by Elayne Trakand also left the user appearing misty and insubstantial.
Mesaana orders Sheriam Bayanar to steal all nineteen sleepweavers from the rebels in addition to ordering that she cause Egwene to be deposed. She threatens to cut off one finger or toe from Sheriam for each sleepweaver not obtained within three days. Before Sheriam is stilled and executed by order of Egwene, she is seen with a bandaged hand. Since Siuan Sanche still has possession of one of the sleepweavers, it is likely that Mesaana carried out her punishment and removed one of Sheriam's fingers.