My DD used to have them when she was younger. Seems to coincide with a coupld od things - developmental plus food she was eating. The few times the night terrors occured she had eaten BBQ Sakatas - so I am tipping some sort of preservative may have set her off. Once I stopped her eating them, she was fine. I also would encourage you not to try to wake them - this only prolonged our DD settling back to sleep. We used to just follow her around the house to make sure she was safe but stopped trying to get her back to sleep or wake her up. GL