Just chiming in to agree.
From the SRD:
"Rest: To prepare her daily spells, a wizard must have a clear mind. To clear her mind, the wizard must first sleep for 8 hours. The character does not have to slumber for every minute of the time, but she must refrain from movement, combat, spellcasting, skill use, conversation, or any other fairly demanding physical or mental task during the rest period. If the wizard's rest is interrupted, each interruption adds 1 hour to the total amount of time she has to rest in order to clear her mind, and the wizard must have at least 1 hour of rest immediately prior to preparing her spells. If the character does not need to sleep for some reason, she still must have 8 hours of restful calm before preparing any spells. "