Its classic symptoms are dizziness and a rapidly increased heart rate when getting to one's feet, because the body cannot adapt to gravity.
POTS may affect as many as 1 percent of all teens, about two-thirds of them girls, and though it is usually curable with medication, it can ruin their early years, said Fischer.
"They are missing school and dropping out, bouncing from doctor to doctor looking for a solution," said Fischer, a pediatrician who treats about 100 patients with POTS a year, half of all cases at the Mayo Clinic.
But the outlook for their recovery is "excellent" in about 80 percent of the cases, he said. "When you get through the teenage years, it resolves. After a year or two or three, they live happily ever after."
"Nothing is broken, but the system is just not working right," said Fisher. "They can get better. We don't want them to think they are stuck with this for life."
The problem is the devastating psychological toll the disorder takes on growing girls like Hayley.
"The key is not to abandon life along the way," he said. "They have no energy and have a tendency to drop out of school and mess up their lives. When the POTS is gone, we want them to still have friends and have made academic progress."
While early diagnosis may not necessarily cure these girls any faster, intervention with drugs like beta blockers and alpha agonists that act on the blood vessels and sometimes serotonins, are important.
Doctors also recommend establishing healthy routines such as aerobic exercise, regular eating and sleeping, and, surprisingly, the intake of extra fluid and salt.
"These kids can't burn the candle at both ends and get away with it," Fischer said.
POTS was first recognized in 1993 and some research has shown an association with chronic fatigue syndrome. It can also strike in middle age, but the prognosis is not as good.
Teens with the disorder seem to share some unexplainable characteristics, according to Fischer.
"Typically, it's high-achieving teens, not the obnoxious type A, but gentle ones that are extracurricular activities and busy having a great time, every parent's dream," he said. "There is something about their body chemistry and thermostat that predisposes them."
POTS strikes sometime during puberty after an illness or injury that somehow "tips something out of balance in the nervous system controls, leaving them feeling tired and crumby," he said.
POTS is often misdiagnosed because it can include a wide array of seemingly unrelated symptoms, including fatigue, exercise intolerance and excessive thirst, according to according to the Dysautonomia Information Network, which addresses disorders of the autonomic nervous system.
In extreme cases, it can cause disabling vomiting as it did for Hayley.
The hallmark of POTS is tachycardia, rapid jump in the heart rate when standing, 30 beats per minute or to a heart rate greater than 120 beats per minute within 12 minutes of head-up tilt.
When Hayley was tested at Mayo Clinic, her heart soared to 180 beats per minute, according to her mother, so high doctors stopped the tilt test.
Hayley's case may not be that unusual -- Fischer has 15,000 hits on his YouTube video and the POTS podcast has 33,000 views.