When emotions turn into nightmares

Jodi Evans, surrounded by her children, suffers from narcolepsy with cataplexy.

By Lisa Ashley Warshaw

Imagine becoming temporarily paralyzed by your emotions. That’s what happens to Jodi Evans, a 33-year-old mother of four.

Ms. Evans and her family, who live in Denton, were at church one Sunday morning two years ago when she lost feeling in her legs. The numbness continued to creep upward, and soon her head dropped. Her body was asleep, but she was conscious.

That was the first time she experienced narcolepsy with cataplexy. 

Narcolepsy, a sleep disorder that causes excessive daytime sleepiness, can be complicated further with cataplexy, an abrupt and temporary decrease in or loss of muscle tone, affecting the limbs and/or trunk. 

Researchers at UT Southwestern Medical Center were among the first to identify the complex causes of narcolepsy, and today their bench-to-bedside discovery helps patients like Ms. Evans as the search for a cure continues.

“The most bizarre trait of cataplexy is that it is triggered by strong, positive emotion,” said Dr. Masashi Yanagisawa, Professor of Molecular Genetics. “In humans, the most common triggers are laughter, surprise, and sexual pleasure, all of which can cause sudden loss of muscle tone.” 

Ms. Evans said that almost every emotion makes her go cataplectic, especially “warm, happy feelings.” The things Ms. Evan’s loves most – her family and faith – are her biggest triggers.

“I literally go to sleep with emotion, and while my body is asleep, I am still consciously awake so I can see and hear,” she said.

Dr. Yanagisawa’s research into this sleep disorder happened rather serendipitously when the mice he was studying began to exhibit signs similar to those of humans with narcolepsy.

“Suddenly the mice would stop moving, fall to their side, and become completely immobile,” Dr. Yanagisawa said. “The mice appeared dead, then after one or two minutes, they would recover and resume normal behavior as if nothing happened.” 

This is when Dr. Yanagisawa discovered that narcolepsy is directly related to the absence of orexin, a brain protein that regulates the body’s sleep and wake cycles. Based on Dr. Yanagisawa’s discovery, this mysterious disorder is reduced to a biochemical deficiency that is now a primary baseline measurement used to diagnose patients.

At the time of Ms. Evans’ diagnosis, she would experience 30 to 40 episodes daily, which left her immobile in bed.

“These symptoms can be enormous challenges for patients like Ms. Evans, potentially making a normal life impossible,” said Dr. Gregory Carter, Associate Professor of Neurology and Neurotherapeutics.

Dr. Carter reminds Ms. Evans that her narcolepsy with cataplexy is so bad because her life is so good. “I encourage her to live her life to the fullest extent possible,” said Dr. Carter, also a sleep medicine physician in the Sleep and Breathing Disorders Center at St. Paul University Hospital, where he cares for Ms. Evans.

Ms. Evans takes daily doses of the stimulant Ritalin and central nervous system depressant Xyrem to help control her condition, although she still experiences three to four cataplectic episodes daily. But she now is able to run a small business and actively participate in her children’s lives.

“I’ve learned to be present in my family life,” Ms. Evans said. “That was something that was missing that I didn’t even realize was missing until I was diagnosed.”

Dr. Yanagisawa’s lab has been able to reintroduce orexin into mice and reverse narcolepsy. However, the same is not true currently for people because the blood-brain barrier protects the human brain from external substances, including orexin. Research continues so that in the future, narcolepsy patients may one day benefit from an orexin-based treatment.


Dr. Yanagisawa holds the Patrick E. Haggerty Distinguished Chair in Basic Biomedical Science.