Lord Zardoz
Explorer
This kind of thing is really like tracking arrows. It will only really matter if the players and DM decides that it needs to matter.
In the instances where I need something like this to matter in 3rd edition, I just apply fatigue or exhaustion penalties to fighters, and declare someone as being unable to memorize spells if they were affected. Assuming that there are Rituals to accomplish things like Rope Trick or Secure Shelter, it will likely be a non issue after level 5 or so.
For 4th edition, I would probably go with allowing an endurance check to avoid those penalties.
END COMMUNICATION
In the instances where I need something like this to matter in 3rd edition, I just apply fatigue or exhaustion penalties to fighters, and declare someone as being unable to memorize spells if they were affected. Assuming that there are Rituals to accomplish things like Rope Trick or Secure Shelter, it will likely be a non issue after level 5 or so.
For 4th edition, I would probably go with allowing an endurance check to avoid those penalties.
END COMMUNICATION