What Is The Syndrome On ‘Silo’?

Each new episode of Apple TV+’s sci-fi drama Silo unearths new mysteries and raises more burning questions in need of answers. From the very start of the series we were eager to learn who built the silo, why the silo’s residents live there, why everything outside the silo is as it is, and when it will be safe for the residents to go outside. But beyond the basics, other pressing questions have popped up, such as, what is The Syndrome?!

Throughout the first half of Silo Season 1, several references to The Syndrome led us to believe it’s a medical condition present only in several members of the underground population. It’s clear that not much is known about The Syndrome — only that it’s feared by higher ups and causes those who have it to occasionally shake and lose control of their movements. But after Charles Martin’s hand shakes uncontrollably in Episode 5, Episode 6 reveals that Billings (Chinaza Uche) has The Syndrome, too.

So what is The Syndrome in Silo? What are the symptoms of The Syndrome? And was the medical condition present in the books by Hugh Howey? Here’s everything we know.

What Is The Syndrome On Silo?

Thanks to eagle eyed Silo fans who spotted a poster on the wall in Mechanical we have some more detailed insights into The Syndrome. The poster in the series displays the following message:

THE SYNDROME

Do you know the signs?

1. Involuntary twitching is the first sign, leading quickly to
2. Shaking of the extremities.
3. Flashes of pain and muscle spasms are next.
4. Balance and movement is severely impaired.
5. If untreated infection will attack the brain, resulting in reduced cognitive function and finally
6. A shut down of the entire nervous system.

For those who are infected or think they may be advice and treatment are free at any Medical Level. You must report your symptoms there to receive the necessary treatment.

The sign concludes with the words, “Don’t be afraid. Be Honest. There is help.” And finally, it notes, “Clean living is the real safeguard.” HMMMM…

For those wondering if The Syndrome is present in Howey’s books, which Graham Yost (Justified, Sneaky Pete) adapted for television, Yost confirmed in an interview that the mysterious disorder was created specifically for the Apple TV+ series. “Talking about that with Hugh, we came up with something called ‘The Syndrome.’ It’s a neuralgic response to the pressure of living in these conditions,” Yost explained.

Some fans predicted The Syndrome may stem from vitamin D deficiency caused by lack of sunlight from living underground. A severe lack of vitamin D can potentially cause muscle twitches, weakness, pain, or tremors, and vitamin D is associated with a number of health conditions including Parkinson’s disease and multiple sclerosis, which also cause tremors. There are a number of other medical explanations linked to tremors, and there’s always a possibility that The Syndrome could be a completely fictional health condition that has no connection to the real world. Eight episodes into Season 1 we’re still unsure! But since Billings is a main character in the series we’re hopeful that The Syndrome will continue to be explored down the line.

Billings And The Syndrome

We already knew that Billings had The Syndrome and was keeping it a secret so he could keep his job, but in Episode 8 — which premiered on June 16 — we get a deeper look at the impact the medical issue has on his life. After Billings arrives home for dinner and grabs a plate, his hand seizes up, causing him to drop and break the dinnerware. His wife is supportive as usual, but she tells him his tremors have gotten worse since he started working upstairs, suggesting that stress can bring on and exasperate the shaking.

Towards the end of the episode, after Sims (Common) and Holland (Tim Robbins) detain Juliette (Rebecca Ferguson) and have Billings lead her upstairs to “go out,” Billings has another tremor and Juliette takes the opportunity to break free from his grasp and escape by jumping over the railing.

Will Sims assume Billings let Juliette go to save her? Or will Billings’ cover be blown? We’ll have to wait and find out. But since Silo has made it clear that The Syndrome is not contagious, nor does it seem to be genetic, one could assume it’s directly caused by the unnatural living environment, and thus, may improve if the person experiencing symptoms were to go outside and getting exposure to natural light. Even more motivation to leave the silo! Beyond the pure, unfettered joy of getting to wipe the window clean, of course.

Silo is currently streaming on Apple TV+