There are two types of Slumber for the Inanimae. In either case the fae is held immobile in their Anchor, waiting to become active again. The first is Shock Induced Slumber and it is the most common. When a Husk is destroyed, the Anchor is threatened, or massive trauma is experienced, the fae may flee active life and Slumber, usually for no more than a few weeks. The Fae may also enter this slumber voluntarily, usually to regenerate a Husk or find protection from Banality. The duration is only about one tenth of the time of Shock Induced Slumber.
The second type of Slumber occurred during the Shattering and is referred to as the Somnolence. This can last for months, years, or centuries. Only the most dire of trauma will cause this.