Thanks ladies.

The last couple of nights we haven't had one, so that is a bit of a relief. Mind you he did sleep walk one of those nights... I'm still stumped as to what may be causing them though. In the last week or two he's finally started getting decent sleep (sleeping longer in the morning and having a longer nap) so I don't think overtiredness is a factor. I also don't think it's food related, I'm a little bit obsessed with checking everything on Additive Alert and know that there aren't any concerns with anything he eats. Grapes could be a factor... The only other thing I can think of is the heat, both of those days were 35 degrees here in Melb. I read somewhere that a fever can be a contributing factor, so I can't help but wonder if hotter weather could play a part...