Narcolepsy: More than just falling asleep on the job

Check out this short video of "Rusty the Narcoleptic Dog." I was first introduced to Rusty in a video presented to my high school psychology class. As expected in a classroom full of teenagers, we erupted into a fit of laughter when the happy-go-lucky dachshund suddenly collapsed into a deep sleep:

Gallup polls reveal that 56% of Americans complain that daytime drowsiness is a problem in their lives, the majority of which is caused by sleep deprivation. A controlled, objective scientific study once revealed that 34% of participants were considered "dangerously sleepy," even when they didn't complain about daytime sleepiness.

America is a sleepy country—but narcolepsy takes it to a whole new level. Imagine feelings of exhaustion at all times, accompanied by inappropriate sleep attacks. Sure, falling asleep on the job is embarrassing and unprofessional, but also imagine the danger of a narcoleptic attack while driving. What is narcolepsy, and what causes this mysterious disorder?

What is narcolepsy?
Narcolepsy is a curious disorder characterized by excessive sleepiness. The sleep attacks are particularly strange; typically, it takes us at least an hour of sleep to reach the REM (rapid eye movement) stage—the period during which we dream and our muscles are essentially paralyzed. In narcoleptics, however, they're locked into REM in as quickly as five minutes. Additionally, when experiencing a strong emotion, some fall into a state of cataplexy, or a sudden muscular weakness. This can result in something as benign as facial drooping to as dramatic as a total collapse.

Narcolepsy is a sleep disorder, not caused by psychological problems or mental illness. Occurring more often in men, there is a wide variation in diagnosis between countries. In Japan, as many as 1 in 600 people are diagnosed; Israel comes in at just 1 in 500,000. The rate for the United States is 1 in 2,000.


A genetic link
People with narcolepsy are more likely to have a relative who also has the disorder, suggesting that the disorder is genetic.

Indeed, a correlation has been identified between narcoleptic individuals and variations of the human leukocyte antigen (HLA) gene. Certain variations in this gene appear to increase the risk for an autoimmune response against particular neurons in the brain.

Hypocretin (orexin)

The affected neurons are responsible for producing a protein called hypocretin (A.K.A. orexin), which controls eating and sleeping patterns. Narcoleptic individuals with the HLA gene mutant have reduced hypocretin, suggesting its possible role in disrupted sleep.

In 2004, Australian researchers found that mice injected with antibodies from narcoleptic humans developed narcolepsy-like symptoms, another link suggesting that it may be autoimmune.


Narcolepsy and...flu?
Anyone who has contracted the flu or some other virus can relate to the inexorable tug of sleepiness and—many times, most likely—fell asleep at the drop of a hat.

Even when I got my flu shot back in October, I was exhausted. I slept 10 hours that night. Woke up, made pancakes, ate them in bed, then put the plate on the floor and promptly fell back asleep. I spent the remainder of the day studying for an upcoming exam and nodding off every few minutes.

Is this all more than simply your sick body's way of forcing you to rest?

Currently, researchers are investigating a link between the swine flu (H1N1) vaccine Pandemrix (GlaxoSmithKline) and an increased prevalence of narcolepsy in Irish, Swedish, and Finnish children post-vaccination. This particular vaccine is unique because it is "double-boosted." Thirty-seven new cases of narcolepsy were documented in Finland, in comparison to the annual average of three.

Last August, a study published in Nature Reviews Neurology described how the number of narcolepsy cases in China tripled after the 2009 swine flu pandemic, a country where only 6% of the population received flu shots.

In retrospect, the narcolepsy/immune system link may have been unknowingly established for awhile. Interestingly, in the years following the 1918 flu pandemic, doctors had described a seasonal sleepiness they termed "encephalitis lethargica."


The future of narcolepsy
Current treatments range from stimulants (meth-/amphetamines) to long naps, but is there a hopeful future for individuals suffering from this potentially dangerous disorder?

A study published by Harvard researchers in 2004 found that transplants may function as long-term, non-pharmacological therapeutic—in rats so far, anyway.

In this study, rat hypocretin-containing cells from the hypothalamus (a brain region largely responsible for endocrine function) were grafted to the pontine reticular formation (involved in arousal and awakening). The grafts appeared successful, compared to tissue taken from cerebellar cells, which do not contain hypocretin.

In the meantime, individuals suffering from narcolepsy learn the best ways to cope. Perhaps the most famous narcoleptic in history, Winston Churchill, evidently made the most of it, offering some words of wisdom: "You must sleep sometime between lunch and dinner... Take off your clothes and get into bed... You get two days in one. Well, at least one-and-a-half."

Photo courtesy Narcoleptics.net, Wikipedia, Sleepy G's, and Sunlight Uplands. Video courtesy crusheddiamonds (YouTube).

Arias-Carrión O, Murillo-Rodriguez E, Xu M, Blanco-Centurion C, Drucker-Colín R, & Shiromani PJ (2004). Transplantation of hypocretin neurons into the pontine reticular formation: preliminary results. Sleep, 27 (8), 1465-70 PMID: 15683135

Wood, H (2011). "In brief." Nature Reviews Neurology, 7 (10), 537.