Elven Spell Recovery (3.5e Feat)
From D&D Wiki
Elven Spell Recovery [Racial]
Your elven 4-hour trance is just as restful as a normal 8-rest.
Prerequisite: Elf,Elven trance ability, Class features that require rest.
Benefit: So long as you spend the time trancing, you only need to rest for 4 hours to regain spell slots or psionic power points.
Normal: You require the full 8 hours of rest usually required
Special: This feat can apply to any feat, ability, class feature or the like that requires 8 hours rest, but not one that requires an explicit waiting period that is not explicitly stated to require rest.