DD has had a couple that sound like this, but only went on for 10 minutes or so.

I looked into them and was told they usually happen at the same time after the child goes to sleep every night. And if they become habitual, to time them, set your alarm and go in and wake them (give them a drink or something) 10 minutes or so before it would usually occur, for a few nights to break the cycle. Don't know if it actually works as they haven't become habitual here so haven't given them a go yet.

Boys are more likely to have them then girls too.