Brianna Minnich, nine, spends each night tucked up in bed beneath the UV lights she needs to help battle the rare disease which can sometimes lead to brain damage.
Her skin and eyes turn yellow whenever she has a sudden change in mood caused by illness, injury, stress, being bullied at school or even arguing with her brother.
Brianna, from Whitehall, Pennsylvania, suffers from Crigler-Najjar syndrome, a rare illness that only around 200 patients in the world - and just a handful in the US - suffer with.
The condition means she has dangerously high levels of bilirubin, a naturally occurring waste product from the blood usually broken down by an enzyme in the liver.
Currently Brianna has to sleep under a 4ft bank of phototherapy lights over her bed. But as she gets older it's likely she'll need a liver transplant which can cause complications.
The UV rays from the blue light affect the bilirubin in her system when they come into contact with her red blood cells and skin tissue.
By helping to manage bilirubin levels in her body and keep them at an acceptable level, Brianna is saved from any long term damage.
Her dad Bob, 29, said: "Her bilirubin levels were considerably high, right up in the high twenties for the first month or so after being born.
"We were told soon after the diagnosis that she was only the 52nd person in the country to have the disorder and just the 212th in the world.
"In the past three or four years her body has maintained a much more steady level of around 10-15 - the average person has a level of around 0.5 so it's still very high.
"She was started on Phenobarbital immediately, and used what was called a 'bili blanket' which is a small phototherapy blanket until she grew out of it.
"Whenever she is unwell and believe it or not whenever she has a sudden change in her mood such as getting upset at her brother or if she gets bullied then her skin tone changes drastically to a much more visible 'yellow' until she calms herself back down.
"She also sleeps under a 4ft long bank of phototherapy lights every single night, for at least 9 hours a night which typically keeps her skin tone fairly 'normal'.
"The only thing you can really see is her yellow eyes - people ask us all the time 'why are your daughter's eyes yellow?"
After being born Brianna underwent tests and was constantly in and out of the hospital for two weeks before finally being transferred to the Children's Hospital of Philadelphia.
She was eventually diagnosed with Crigler-Najjar syndrome at two-and-a-half weeks old and spent the best part of a month in hospital before being released.
Phototherapy has helped bubbly Brianna however the treatment becomes less successful as she grows up so her dosage of phenobarbital must increase.
The daily medication helps jump start her liver but whenever the dosage is increased it causes her to feel lethargic for weeks and constantly falls asleep at home and school as well as leaving her feeling depressed.
[Related: Routine eye test diagnoses cancer]
Bob added: "It's difficult for her social life - having sleepovers at home is hard due to her lights and we have not allowed her stay at her friends house due to not having the lights.
"During the winter months it's even harder since we don't have the bright sun to use to our advantage as the UV rays also act as a natural phototherapy light.
"Long term effects of the lights include having gallstones, so normally a Crigler-Najjar patient eventually has their gallbladder taken out.
"The lights are also very bright and will likely affect her eyes. The medication she takes is a barbiturate so taking it for the rest of her life is also going to cause problems.
"Her disorder will never go away, with the exception of getting a liver transplant. There have been talks of an experimental process called gene therapy, but it has been in the testing phase for years due to the lack of funds for research.
"While we were in the Children's Hospital of Philadelphia after she was born, my wife and I were both tested for compatibility, and it was determined that I would be a good donor.
"The process would take a portion of my liver and have it implanted into her body, which will than grow into her.
"The problem with the transplant is that she will still be taking anti-rejection pills the rest of her life and there are many risks in the transplant.
"We know families who have had the transplant, and in return, have had many problems and complications afterwards. We have been told that we would need to make a decision on the transplant by her pre-teens."
Brianna, who also lives with her mum Brooke, 28, and brother Brenden, six, hasn't let her illness stop her from aiming high and one day hopes to become a famous television star.
Bob said: "Brianna loves to sing, play guitar and draw and has also been in multiple plays and dance performances for school - she is the typical 'artsy' type of young girl.
"On top of her creative mind she also likes playing softball and riding bikes.
"She asked us if we could put her in a six week modelling and acting class that she saw on television. Since the day she graduated she talks everyday about becoming famous and one day having her picture in a magazine or being on a hit Disney show.
"Although we haven't yet heard anything from the agents office I tell her each day to never give up faith that maybe one day she'll get her big break."