Why does my son wake up in the night?

My son is 8 and was diagnosed with mild aspergers syndrome aged 4.  He was a terrible sleeper as a small child - I had to buy a double bed for us both until he was 5 when he went into bunk beds.  All seemed better until he changed school last September and since then has reverted back to waking up and coming into my bed.  He now cannot go back to sleep without me next to him!  I have tried making him stay in his own bed but he gets extremely distressed and wakes the whole household.  I am now getting quite worried as this seems a terrible habit which he can't break.  He still finds any change quite tricky so I presume the waking up in the night is related to the change in school although he is very happy there.  Please can you give me any advice

[KarenDiane]

My daughter is an Aspie, and I could not get her to sleep without me until she was about 5. She had to sleep holding on to my arm. She hasn't reverted back to it, but I imagine you are correct in linking his sleep problems to changing schools. Transition is so hard for these kids. Have you tried a large stuffed animal for him to sleep with? My daughter is 13 and still needs something to wrap her arms around.