Nightmare

In The Sims 2, Sims can have nightmares if players haven't been taking care of them. They will have nightmares if, they go to sleep when they are hungry, have to go to the bathroom, or are dirty, etc. They also have a much higher chance if they passed out from exhaustion and the player made them wake up and go to bed. They can also have nightmares if they are in an aspiration desperation or are in the red. For example, if your Sim just witnessed a death or just lost their job, they will more than likely have a nightmare. Nightmares also exist in The Sims to some extent, as they tend to wake up if their motives are deep red.

The Sims Medieval
Occasionally, sleeping Sims will recieve a message describing a dream he/she is having. The player will then be required to select one of two options in which to handle the dream. Depending on the player's selection, the Sim may recieve a "Nightmare" buff which subtracts ten Focus and lasts seven hours. If the player chose correctly, however, the Sim may recieve positive buffs or even cash.