Monsters under bed

Monsters may appear underneath beds in The Sims 3: Supernatural and The Sims 4. However, only children can see and interact with them.

The Sims 3: Supernatural
In The Sims 3: Supernatural, the player can direct a playable child to check for monsters underneath a bed. They may also do this autonomously. The child may obtain either the No Monsters or the Monsters & Terrified moodlets. The No Monsters moodlet will give a +15 mood boost, while the Monsters & Terrified will give a -15 mood decrease, and the child will be unable to use the bed they checked. Brave Sims are more likely to get the No Monsters moodlet, while Coward Sims are more likely to get scared.

The Sims 4
In The Sims 4, monster repellant can be purchased to ward off monsters; Sims may also attempt to befriend the monster. This, however, can fail. After becoming friends, the child can either talk or play with it. Monsters can be kept away by older Sims spraying the bed, having the "Coolala Defender Light" in the same room, or by asking them to leave if the child has befriended with the monster. When a monster is sighted, the child will become scared and will receive the "Monsters under bed" moodlet. When inflicted with this moodlet, the Sim will not sleep at all. They may run to their parents or older siblings for comfort afterwards.