Silo: The Syndrome Illness Explained

There’s plenty to try and wrap your head around while watching Apple TV+’s “Silo.” It’s a dystopian series following civilizations that live in underground, well, silos. Mysteries are bound to arise. While the oddities of the Safeguard Procedure may be what comes to mind when you first think about the show, there’s also “the Syndrome,” an illness that residents might experience. At this point in the series, we still don’t know the cause of the Syndrome. However, the symptoms are clear and well-advertised to the residents. That can help us speculate as to its origin — and reading the books by Hugh Howey won’t clear up the matter. The Syndrome is new to the TV series.

There is a particular way the Syndrome presents in the population. According to posters put up around the community, a victim begins presenting with involuntary twitching that progresses to full limb shaking. Next comes body pain and muscle spasms, which then starts to impact a sufferer’s balance. At this point, if the afflicted don’t receive treatment, their cognitive abilities decline as nervous system function becomes atypical. It doesn’t sound pleasant, and the posters don’t say how to prevent it. If you start to have symptoms, you have to report for treatment. Their only advice is that “clean living is the real safeguard.”

Though the cause of the Syndrome is unknown, there are plenty of theories based on the symptoms. Most are related to the fact that residents live underground permanently, which human bodies weren’t designed to do. Because people can hide their diagnosis (up to a point) without impacting those around them, it isn’t easily contagious. That means it’s more likely to be something rooted in a deficiency. Being underground for a lifetime could result in different vitamin deficiencies, like vitamin D, that may not be supplemented appropriately with their food supply.

There’s also the possibility of a bacterial infection. This could be what the “clean living” phrase on the posters is referring to. In living underground, the silo residents may be exposed to things they wouldn’t normally encounter, and following hygiene protocols with regard to hand and food washing could be the best form of prevention. “Clean” could also refer to clean eating, like working to maintain your physical health through a healthy diet and exercise, keeping your body strong so you don’t come down with the Syndrome. 

The Syndrome is serious enough for people to lie about — Deputy Billings (Chinaza Uche) is hiding the affliction, and that’s why he’s helping Juliette (Rebecca Ferguson) — but people aren’t killed or even quarantined for coming forward. A resident isn’t allowed to hold public office if they have the Syndrome, which makes sense since many of the symptoms are rooted in a loss of cognitive ability. It implies that those running the silo are concerned if people start to exhibit the signs, and that the illness isn’t a death sentence. This only makes it all more puzzling. 

The Syndrome may simply be rooted in a mental reaction to underground confinement. It’s not something humans are designed for, and there’s a chance that it is starting to impact the minds of those in the silos. The show’s creator, Graham Yost, has given a bit more insight on the matter in an interview with SFX Magazine (via Collider). “Human beings weren’t meant to live like this. Talking about that with Hugh, we came up with something called ‘the syndrome’,” Yost said. “It’s a neuralgic response to the pressure of living in these conditions.”

Neuralgic conditions are often linked to a chronic illness, or found as a result of aging. This could imply that, rather than an infection or deficiency, it’s a condition that’s evolved over time. It effectively becomes a maladaptive reaction to a less-than-ideal living environment. Hopefully the upcoming Season 3 will give us more insight.