WriterofDreams - I'm not saying it is abnormal to have nightmares, I am just saying that not all children have nightmares.
Now my children where sleep is concerned are very unusual because they are all excellent sleepers and since 6 weeks old have slept for 12 hours straight. Now I know this is unusual, but it is the case. There have been many times, where I've stood checking that they are alright, to hear them gently snoring and sparko and 9am in the morning. This is the envy of my friends.
So one thing I am very confident on is, that sleeping anywhere, and especially under their own duvet in their familiar surroundings at boarding school or home, is not an issue. And yes, if they should wake up in the middle of the night, I would want to know about it, and I am confident that they/schoool would comment on this to me, as it would just be so out of character.
But that is a thing with my children.
I know friends' children at 13/14 years old cannot go for sleepovers due to a range of reasons, panic attacks, bed wetting, sleep walking etc. Would I recommend their child going to boarding school no, but nor would I recommend that they go on a regular school trip which they do not do.