My DD and DS have been having a bad time with nightmares for what seems like months now. There's hardly ever a night - maybe one per week - where they both sleep right through without waking in tears, sometimes hysterical. DD (4) is the worst, but DS occasionally hallucinates, has terrible nightmares, and ends up wetting himself. They share a room but when one of them wakes up, upset, it doesn't wake the other, luckily. It's usually hours apart.
I just don't understand what's causing them to have such disrupted sleep. The room is quiet and dark, and it's not as if there's any disruption or trauma in their lives to cause them to have nightmares. They watch virtually no TV and certainly no scary adult stuff with violence in it or anything. Since school finished at end June (we're in Scotland), they've had one day of wall-to-wall CBeebies when I was ill, and one DVD. That's the sum total. They usually say (when they're coherent) that the nightmares were about monsters chasing them, witches, or spiders.
I also have a 15-month old in his own room, and I honestly can't remember the last time I was up in the night with him!! It's been months and months. Ironic.
DP has scary nighttime incidents as well, and he frequently adds to my total wakenings, so I'm a bit worried the whole thing's hereditary and this will be my life from now on ... 
- though in the past DD and DS have been fine at sleeping, so I don't see what's changed now!
Any tips gratefully received, as I was kinda hoping to have my nights back by this stage ... 