The Centre for Disease Control and Prevention is investigating a rare and fatal disease that causes the sufferer to have progressively worsening insomnia.
CDC's National Centre for Emerging and Zoonotic Infectious Diseases has investigated the disease following the death of a 16-year-old boy from North Carolina.
The boy suffered from progressively worsening movement, speech and memory problems for three years before he died.
Doctors were unable to diagnose his problem until after he died, when they realised he was suffering from sporadic fatal insomnia – the youngest person to have ever developed the disease, LiveScience reports.
Sporadic fatal insomnia, or sFI is an extremely rare condition – fewer than 10 cases have been recorded in history – caused by prions, or proteins that are folded abnormally.
It is similar to Fatal familial insomnia (FFI), in which worsening insomnia leads to hallucinations, delirium and confusion. Also extremely rare, just 100 cases of FFI have been recorded and the average sufferer lived for just 18 months after getting the disease.
The CDC published the report on the North Carolina boy to raise awareness of the condition.
FFI sufferers get increasing insomnia which can result in panic attacks and paranoia. This is later followed by hallucinations as a result of not having any sleep. A complete inability to sleep then follows and after around six months, the sufferer will get dementia and eventually die.
The boy started getting symptoms in 2009 after developing slurred speech and double vision. Over the next few months, he started having trouble writing, memory problems and an inability to balance.
After being admitted to hospital, doctors said he was exhibiting involuntary movement in his arms and legs and, as he became increasingly less mobile, was eventually confined to a wheelchair.
Over the next two years, he began having difficulty chewing and swallowing. He was admitted to hospital with pneumonia in 2011 and five months later, in February 2012, he died.
A post-mortem examination of his brain showed he was suffering from a prion disease, and that there was no "trigger" for the abnormal protein, leading them to diagnose sFI.
Ermias Belay, from the CDC, said: "In the United States, prion disease in [teenagers] is extremely extremely unusual. This is the youngest patient, that we are aware of."
Belay said insomnia was not noted as one of the boy's symptoms, but noted this can be missed because of the patient's other problems. "They may be struggling with sleep, and they may not be able to communicate that."