I just thought of a campaign premise that could work quite well...
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Don't rest your head; don't go to sleep.
Because every-time you do so, you go in a little deeper.
You were all just normal folk, regular folk, living your regular lives... until you had the Dream.
In the Dream, you are told to kill a family member, or a similarly heinous deed, or the one who sent the Dream would take things away from you.
Then you woke up, and went on your merry way... to find that your prize cow is gone. And no one remembers that you even HAD a cow.
Next time you slept, you had the same dream.
Next time you woke up, your favorite tools would be gone, or a portion of your life's savings. And it steadily, more and more important things... change.
Your wife is married to another man, and you are thrown out of your house as a burglar.
Friends you've known for years turn their backs on you, spitting in your face.
You become destitute, your valuables simply... gone.
The only other ones that remember things as they SHOULD be are the other PCs... and even then, you aren't sure about that.
Now, it is up to you to stop whoever the one in the dream is, because, should you ever commit the heinous deed that it wishes, the next night, the dream just asks for something even worse. Something that seems to hint towards a sinister plan...
You're in luck, though; you are immune to magical sleep, now, and the changes only come once you go to sleep.
Good luck.
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Basically, this would have to have the following details set up to work:
-You would need to emphasize the sheer exhaustion of the characters; any spells that they may purchase to stop their bodies from feeling fatigue won't stop the mental effects...
-Don't make all of the changes negative; have a minor enemy become an ally, or have a couple copper pieces transform into gold pieces. Do this seldom, and don't make it too positive... and they'll be paranoid about their being a catch.
-Did I mention people hallucinate from lack of sleep? Didn't I? Because if I didn't... Lucky, lucky.
-Have some of the horrible things that happen be something like adding minor (and later major) crimes to their record, them having stolen goods, they look like gypsies. Basically, they are blamed for crimes they never committed (like, oh, I don't know, killing a noble).
-One of the possible drawbacks of sleeping could be a reversal of an unimportant plot details, like having a man they killed be perfectly alive and safe, or have the goblin camp they just ransacked be alive and well, thank you... while they're in the middle of it. Don't do this too often, or the PCs will feel powerless, which isn't very fun, in my opinion.
-The crowning touch to this would be giving everyone semi-detailed packets of campaign backstory (and make sure they read them; they don't have to be complicated, maybe just a page or two of bullet points, containing a bit of character backstory and such)... and have everyone's be slightly different. This does add a bit of paranoia, especially if you can get any player that figures it out to play along; second-guessing yourself is rather frightening...
-If you want to set it up this way, this could be an Elder Evil campaign, with the sleep-alterations being part of its sign.
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So, what do you think?