Megadungeons: Don't Fall Asleep!

"Good luck young adventurer! The Forsaken Halls await you. But a word of warning: do not fall asleep - it is said that those who slumber in the Halls will awaken only to madness! If you absolutely must pass a night in the Halls, seek you a place of sanctuary, such as a shrine of Law. Heed me well, for the town asylum is full of those who did not!"

Sleeping in the Forsaken Halls is not a good idea. Anyone sleeping for more than a consecutive hour must Save (vs. Spells) or wake up completely mad (Wis 1). The madness of the Halls plunges the victim into a waking nightmare, screaming, weeping, and flailing until remove curse or some similar healing is administered.

There are, however, a few safe locations in the Forsaken Halls. The challenge is testing them.

Taking a victim out of the Halls' can be dangerous too, due to all the screaming and wailing. Double the chance for wandering monsters.

This is a good way to discourage players from stopping to sleep every time the Magic User uses his magic missile spell up. The saving throw is an interesting way to handle it, because as characters level, their chance of making it through the night unharmed gets better. It also makes an interesting default trap out of simply getting the characters stuck in a room or difficult level for a long time, and have to start making some kind of save or check to stay awake!