What Is Narcolepsy?

You’re just about to start studying for final exams, and you know you’re going to need something to keep yourself awake all night. So you’re waiting in line at the grocery store, prepared to stock up on energy drinks. The person behind the counter turns to you, smiles, and asks how you’re doing. Promptly, you collapse and fall asleep on the floor.

Okay, so maybe that doesn’t happen to most people. But if you have narcolepsy, spontaneously falling asleep is something that you may routinely experience.

Narcolepsy is a chronic brain disorder characterized by the inability of the brain to properly regulate sleep-wake cycles. With narcolepsy, a person might feel constant overwhelming daytime sleepiness, and experience sudden, irresistible bouts of sleeping. For reference – the exhaustion you feel after pulling a study-motivated all-nighter or two is probably comparable to the level of exhaustion a person with narcolepsy might feel during any given day, even after a full night’s rest. In addition to a difficulty staying awake, people with narcolepsy may also have difficulty staying asleep, and may suffer from a variety of sleep disorders.

Roughly 70% of people who suffer from narcolepsy also experience cataplexy. Cataplexy is a sudden muscle weakness triggered by strong emotions – essentially, it’s an abrupt loss of a person’s ability to control or move their own muscles. This typically causes the person to collapse and be immobile, unable to move despite the fact they are fully conscious.

Hypocretins

Recent studies have revealed the mechanisms in the brain behind narcolepsy with cataplexy, and it has to do with special neurotransmitters called hypocretins. During waking hours, hypocretins are released from neurons in the hypothalamus and bind to hypocretin receptors on target neurons, promoting wakefulness and suppressing rapid-eye-movement (REM) sleep. Essentially, if you’re awake, hypocretins are partly responsible for keeping you that way.

People with narcolepsy, however, have drastically fewer neurons that produce hypocretins, meaning that their brains aren’t getting those signals to stay awake and to stay out of REM sleep. Many researchers suspect that these reduced neuron numbers make it exceptionally easy for a narcoleptic individual to cross the barrier between wakefulness and sleep randomly and frequently. It may also cause a blurry line between sleeping and wakefulness, resulting in some of the other symptoms of narcolepsy, such as dreamlike hallucinations while awake.

The graphic below depicts the reduced number of hypocretin-producing neurons in the hypothalamus between those with narcolepsy and those without narcolepsy

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http://healthysleep.med.harvard.edu/narcolepsy/what-is-narcolepsy/science-of-narcolepsy

Genetics

Researchers have also found that genetics has some role to play in narcolepsy. Many people with narcolepsy carry a certain gene that codes for the human leukocyte antigen, which plays a role in immune function. Other genetic factors shown to influence development of narcolepsy also seem to have immune-related functions, suggesting that the immune system may be killing off the neurons that generate hypocretin.

Conclusion

Narcolepsy is a complex sleep disorder influenced by a variety of factors, not all of which we know. But gaining a deeper understanding of the underlying mechanisms of narcolepsy can help scientists focus on treatments and cures for this disorder (currently, there is no cure for narcolepsy). Ultimately, we can create a better quality of life for people with narcolepsy.

References

“Understanding Narcolepsy.” Healthy Sleep. N.p., n.d. Web. 06 Nov. 2016.

“Narcolepsy Fact Sheet.” National Institute of Neurological Disorders and Stroke, 6 Apr. 2016. Web. 05 Nov. 2016.