Nightmares? What do you think?

[Mugsybalone]

Hi there. Our dd is almost 18 months old and has been sleeping through (11 hours) in the main since she was around 10 months old. She would occasionally wake and need to be resettled though not often.

Over the last month or so, she has started to wake every other night or so. She wails (that is the only way I can describe it) for up to a minute, will then be fine for a couple of minutes then she'll start wailing again. This can go on for up to an hour.

For some of these wailing episodes she will stop on her own, other times we go in to calm her (all she needs to stop the wailing is a hand on her back or chest). When we do go in, she is always lying down seemingly asleep (i.e. not standing up or hoping to be picked up like she would normally waking in the night).

I'm thinking she may be having nightmares or something? Is there anything anyone can suggest to help? I'm hoping this is just a phase.........

Thanks in advance.