>> My 4 year old daughter pulls her hair out in her sleep and recently when
> she is tired or hungry also in daytime.
> She has a big bold spot now on top of her head. Are we dealing here with
> a neurological disease or what is the diagnosis ?
No-one on this group can tell you what the diagnosis is - at least, not
based on the information you're giving us. The son of a friend of mine
began doing this during his first year at school. They sought medical
advice, and were told it was probably related to stress (possibly
bullying by other children, or maybe just the stress of unfamiliar
circumstances). They talked to him about it, and the behaviour
subsided. I don't think they ever worked out what the stressor was, but
the behaviour hasn't recurred.
There could be a neurological basis, but there's no point jumping to
conclusions. Consult your family doctor, and allow them to point you to
a specialist if need be.