All children have the occasional bad dream.
But in Bangladesh refugee camps, Rohingya children are too scared to sleep at all.
An estimated 537,000 refugees have fled to Bangladesh from Myanmar's Rakhine state since late August, escaping what the United Nations dubs a "textbook case of ethnic cleansing".
Save the Children emergency health unit director Unni Krishnan has been in Canberra this week to paint a picture of the dire humanitarian situation for federal politicians.
The Turnbull government has allocated an extra $20 million to the humanitarian crisis in Myanmar and Bangladesh in September but is being urged to chip in further.
Next Monday the UN is holding a donor conference in Geneva and wants to raise $434 million in emergency funds.
Dr Krishnan said many children are showing signs of post-traumatic stress disorder such as nightmares and flashbacks.
"Mothers say their children don't sleep," Dr Krishnan told AAP.
"If they ... do doze off they wake up screaming - remembering what has happened."
Save the Children is setting up special kids' zones in the camps for youngsters to play, sing songs and do art.
Myanmar's Buddhist majority denies that Rohingya Muslims are a separate ethnic group and regards them as having migrated illegally from Bangladesh, although many families have lived in Myanmar for generations.
Another aid group, CARE, estimates that close to half a million refugees living in the camps have either witnessed or experienced sexual violence including rape.
"Many women and teenage girls suffer in silence," CARE's Bangladesh country director Zia Choudhury said.
The organisation is setting up four centres over coming weeks to help 30,000 sexual violence survivors.
Dr Krishnan said there was a lack of basic healthcare, clean water and toilets and sanitation in the camps.
Large numbers of children were suffering acute respiratory infections and were also at risk of dehydration, which could kill them within six hours.
He said there had been 24,000 cases of diarrhoea reported.
The UN last week began a mass vaccination program to prevent a cholera outbreak.
