4 year old waking

A friend of mine is having a bit of a trial with her 3 yr old at the moment.

He is a very bright (understands things quickly and easily) and affectionate boy, quite fair. He is of average build but his mother has noticed that recently he has grown a bit and lost his pot-belly.

As I said, he is very affectionate, often telling parents he loves them and that they are the best in the world. However, he is becoming more impressionable and picking up violent behaviour and rude words from other children. Fairly normal I am sure, but particularly noteable in him.

he loves cold drinks, especially milk. He very rarely has sweet (sugary) food or drinks and loves boiled eggs, fruit, cucumber and eggs.

He becomes sad and weepy if other children don't want to share things with him. He becomes angry when surprised by discipline (grabbing his arm sharply when he tries to run off, for example).

He is curious and likes to know how things work.

He is very regular in passing a motion each morning.

He flushes on exertion.

He kicks the bed clothes off during the night and moves alot during sleep. If he does not kick covers off his mother notices that his forehead and temples become sweaty.

The main problem is that he wakes up every night, after midnight, perhaps two or 3 times. he is not crying or scared, but calls out for his mother. When she gets there he is simply affectionate and wants to play with her hair.

Because this happens so often and he never stops calling for her once awake, she usually ends up sleeping in his room so that Dad can get an unbroken night.

She is also concerned with the way he is picking up bad behaviour. For example, while I was talking to her the other day this gentle, affectionate boy ran up to a passer-by and kicked him in the shins.

I don't know how much of this is 'normal' growing behaviour but it is exasperating the mother. Perhaps she needs something more than the child?

Any ideas?