So many nightmares

What stops the nightmares is to increase your toddler's thinking ability by making them check out things and ask 'what's this?' this will raise their mental prowess and end the nightmares. Note: Not all objects in a house will have the what's this interaction.

I haven't played toddlers a great deal but if I recall correctly:

If a toddler had a nightmare I'd send them straight back to bed and select the 'nap' option. They didn't seem to get nightmares from napping.

It's interesting but I never ever read my toddlers to sleep (I have about 8 of them in different households), dont put no music, and they never get nightmares. I think it happened to one of my charmer toddlers possibly 1 time but since everybody else is asleep in the house with locked doors, he just wanders around or goes back to sleep.

With the children however, it was an annoyance with the freakin' monster under the bed. My parent sims could never sleep.

One Simmer suggested I play lullabies on the radio to counteract the nightmares.

So long story short, read to them at night, level up thinking skill, and have them listen to lullabies?

I think it might help if you read you toddler to sleep

I always just send the toddlers back to sleep with the nap option, then once they finish napping I send them to sleep. It's kind of annoying but it beats having the parents to go through the trouble of comforting them and such. Happy simming.