Rodney discovers the science behind a time dilation field but doesn’t tell anyone. He secretly uses his quarters to create his own sanctuary so he can get a good night sleep and then be productive through night to achieve ’science-y things'. No one realizes Rodney isn’t ‘sleeping’ except Sheppard. He knows something is up when Zelenka mentions power spikes every night around the same time Rodney heads back to his quarters. Sheppard ‘investigates’. McKay & Sheppard take advantage of the hours = minutes in Rodney’s quarters.

OR Maybe Rodney discovers it and sets the time dilation field up on a beach on the mainland, and they use it as a ‘vacation spot’ for everyone on Atlantis. People can have a week vacation without disrupting any schedules or daily functioning duties on Atlantis.
(So, basically I just want some fun PWP.)