Most people aged over 25 will most likely struggle (at some point) with growing older, but there probably aren't many who have taken the news quite as badly as five-year-old Sadie Miller.
Sadie found YouTube fame this week when the internet witnessed her desperate pleas for her baby brother "to stay little," because he's "so cute".
"I don't want to die when I'm a hundred!" she sobs hysterically in the video, which has now amassed more than 10 million views.
But Sadie's battle with the realisation of her own mortality is not uncommon among young children.
Child psychologist Clare Rowe said emotional distress over such issues can occur anywhere from about three years of age, but is most common in the transition between preschool and school.
"Issues like death and mortality can be a struggle for certain personality types, so kids that are more anxious in personality and sensitive will start to think about death earlier." She said children with higher IQs will also start to consider mortality at an earlier age.
"But while they can understand death cognitively, they don't have the emotional maturity or age to cope with that realisation," she said.
A fear of death or dying in young children can also be brought on by the death of a family member or a pet, or by a sudden illness, consultant child and educational psychologist Andrew Greenfield said.
"These events can trigger kids to ask more questions and be more inquisitive. However it's uncommon for this to remain an ongoing fear and they generally tend to move on," he said.
Children can also suffer from emotional distress if they get a new sibling or there are other changes in the home.
In dealing with these anxieties, Dr Rowe said parents first needed to uncover the root cause. "If it is a case of the child lacking attention from the parents the answer is not to give attention in a 'baby' way but in an age appropriate way," she said.
"The introduction of a new sibling can cause those disruptions as kids become jealous of each other."
She said toileting, eating and sleeping regressions can all be symptomatic of emotional stress among young children.
As for Sadie, Rowe said she'll take the video with a grain of salt. "That looks like a really tired kid to me. Kids will cry at anything when they're tired," she said.
"Let's be careful not to encourage 'tired kid crying' videos on YouTube."
- Sydney Morning Herald