Myth - PHB pg 178, under rest requirements: "If the character does not need to sleep for some reason, he/she still must have 8 hours of restful calm before preparing any spells." their definition of rest is "does not need to slumber, but must refrain from movement, combat, spellcasting, skill use, conversation, or any other fairly demanding physical or mental task during the rest period".
After resting, a wizard must study his/her spellbook to prepare any spells that day. The process takes 1 hour.
So basically, a wizard needs 9 uninterupted hours of "Leave me the hell alone" time every day, regardless of whether they sleep or not.
*Sorcerors/bards need 8 hours 15 minutes.*
Also, I need a specified 'time of day' for Chevik to pray for his spells (Which takes an hour but does not require rest and has to be done at the same time every day if physically possible) - I presume "dawn"?