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Just found this piece as I was wondering why on earth my DS was sat in bed laughing his head off everynight at 2am - I have been through the night terrors so believe me I am so glad it is laughs now not screams!!!
Anyway, I was searching, found this and it actually really really made me smile. I am a bit emotional already so it could just be me lol but thought I'd share it.
The bit that made me smile was:
"If this is so, then the autistic children in this study expressed more positive emotion -more genuine happy affect- in interacting with another person than did the nonautistic children."
So now when DS is doing his contagious, crazy little laugh when we are playing I will know that he is genuinely happy.