Solo Leveling: What Is the Eternal Sleep Disease? The mysterious illness that changed Jinwoo's life

Time of India

18-05-2025

Though the anime
Solo Leveling
transports viewers into a mystical world teeming with monsters, Hunters, and epic showdowns, it conceals a tragic secret within its thrilling narrative.
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One of the show's most tragic threads is the introduction of a mysterious affliction, called
Eternal Sleep Disease
, that sends patients into a coma-like stupor. Here's all you need to know about it, and why it's so vital to the story.
What is eternal sleep disease in Solo Leveling?
In Solo Leveling, Eternal Sleep Disease is a serious epidemic that causes its victims to fall into a deep sleep for years, stuck in what looks like an eternal coma. It is deeply felt by those who are sensitive to mana—the magical energies unleashed into the world after the Thirteenth Ziggurat Gate opened more than ten years before the game starts.
These gates gave birth to Hunters, elite, magically enhanced humans who slay dangerous magical beasts, keeping them out of civilized society. Not everyone can afford to live close to this clean energy, let alone do so safely. For individuals like
Jinwoo
's mom,
Park Kyung Hye
, just coming into contact with mana was enough to induce a deep sleep that lasted almost four years.
How is eternal sleep linked to mana and hunters?
Though the Eternal Sleep Disease is seen as primarily a consequence of exposure to mana.
Those unable to withstand this fantastic power slowly start to fade to black. First, they can lose consciousness for brief intervals. With each episode, those episodes lengthen until eventually the individual descends into a lasting, coma-like condition—what the
anime
refers to as the 'Great Sleep.'
Since hunters, who are natural mana emitters, produce an environment that is toxic to their loved ones, hunters are unwittingly killing those they care about merely by interacting with them.
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Victims of the disease require extensive medical treatment, including life-support machines run on essence stones—rare energy sources dug from dungeons. Unfortunately, each one of these machines are incredibly expensive, costing millions of dollars. This is why so many families aren't able to afford treatment.
Why the eternal sleep disease matters to Jinwoo's story
What sets Solo Leveling apart is that its main character is driven by more than just power. One of the motivations for him joining the Hunters – even though he is the weakest one initially – was to pay for his mother's care.
Her ongoing struggle against Eternal Sleep Disease introduces high-stakes emotional conflict to the action-heavy series, illustrating the heavy toll of thriving in a vibrant, magical world fraught with peril.
In episode 3 of the anime, Jinwoo makes a trip to his mother's hospital room shortly before entering a deadly new mysterious dungeon. This emotional scene lets audiences feel the full weight of how Alzheimer's disease has permeated every aspect of his life, lending a sense of urgency to his yearning to become stronger.
Who has suffered from the disease in Solo Leveling?
Up until now, only two major characters in the series have been diagnosed with ESD:
Park Kyung Hye – Jinwoo's mother, who spent years in a miracle coma before being saved by her son.
Yoo Myunghan – The father of Jinwoo's best friend, Yoo Jinho, who too succumbed to the disease after a long exposure to mana.
Both of them were subsequently rescued by Jinwoo with a rare magical artifact, but their recovery was a miraculous turn of fortune.
How was the disease cured? The role of the holy water of life
While the disease has no known scientific cure in the real world or the world of Solo Leveling, Jinwoo eventually finds a magical one. Following the completion of 100 floors of the Demon Castle dungeon, he is rewarded with a valuable recipe for the
Holy Water of Life
, a potion with the power to cure any disease.
After Jinwoo uses the first bottle to save his mother, in her hospital room, he then saves Yoo Myunghan, as well. Unfortunately, the potion can only be brewed six times, and all of its ingredients are so rare that this cure would be in practically no one else's reach.
Why the disease as clever piece of worldbuilding
The Eternal Sleep Disease isn't merely an unfortunate subplot—it's an intelligent portrayal from the creators of hidden costs of magic in our world. It beautifully serves as a reminder that the enchanting realm of Solo Leveling, though thrilling, poses tangible risks to even mundane citizens.
It illustrates how new powers can alter social forces and social hierarchies. While some like Tara become more powerful as they awaken, others are abandoned—or even injured simply by being around them. This all raises profound moral questions about equity, sacrifice, and the true nature of strength.
A heartbreaking mystery with real impact
Eternal Sleep Disease is one of the most emotional and thought-provoking parts of Solo Leveling. It makes the magical world feel more real—and gives fans a powerful reason to root for Jinwoo as he risks everything to find a cure for his mother.
As the anime continues, expect this storyline to play an even bigger role in his transformation from weak Hunter to the strongest of all.