The study, presented at an international sleep conference in Cairns, showed 29 per cent of 511 children aged 8-16 took their fear trigger directly from the media.
About 15 per cent linked their fears to a traumatic event like a grandparent's death or bullying at school, and 18 per cent appeared to be mimicking fears felt by a parent or sibling.
The Monash University researchers also found that for about 35 per cent of kids, parents were inadvertently fuelling their fears by reinforcing them when their child got upset.
Lead researcher Jocelynne Gordon said night-time fears were normal, with two thirds of the sample reporting scary thoughts after bedtime, including about half of 16-year-olds.
A fear of intruders was most common, followed by a fear of noises and then bad dreams, according to previous findings.
Affected kids often resisted going to bed and had disturbed sleep.
One third of children said they had not told anyone about their troubled thoughts, a figure Dr Gordon said reiterated the role of parents in helping to stem the problem.