Sound effects to add to the feeling of isolation during the first part of the animation where the girl is going into darkness.
Maybe have narration in the end with the signs as its reassuring – fire alarm research conducted after the death of a family after the smoke alarms didn’t wake them –
“More than 80% of the 34 children aged between two and 13 did not respond to the alarm. Only two children woke up every time and none of the 14 boys woke up at all. “When we started to explore why this was happening and we looked at other types of frequencies of sound we found out that a lower frequency sound … combined with a voice – generally a female voice – was much more effective at waking children up, and in actual fact woke up 94% of children that we tested,”
Soothing female voice narrating at the end with the solutions and the facts showing a realisation that the girl isn’t alone, comfort at the end maybe not the mouse motif again but an arm around her or something more comforting could be a possibility.
At the beginning the mouse could be more threatening or looming – make it look more monstrous?
Using the changing colours, sound effects and narration to define a beginning, middle and end to the animation will give it structure and make it easier to split up the work load.
Computer screen and darkness – see her face not the screen and the messages could pop up? Just the noise and her facial expressions.
Colours – associations of them
look at Adobe tv and Adobe W3c schools for tutorials.