“Bird Box” has been a massive success for Netflix. According to The Verge, more than 45 million accounts streamed the movie in the week after its premiere, and the difficult scenarios faced by the film’s blindfolded protagonist proved so popular that viewers have been covering their own eyes to attempt similar feats. The risky nature of these “‘Bird Box’ Challenges” prompted Netflix to post a Twitter warning. Their mass appeal ties neatly into evolving discussions about the nature of the movie’s antagonists: Some speculate that instead of aliens or demons, a mass psychogenic illness explains the events of the film.

So let’s dive in — when it comes to “Bird Box” theories, does a mass mental illness make sense?

The Story So Far

If you’re not familiar with the “Bird Box” phenomenon, here’s a quick primer. *Spoiler Alert*

A mysterious event — called “The Problem” — causes waves of suicides across the world. Upon seeing something nearby, most affected individuals attempt to kill themselves; when The Problem comes to Los Angeles, main character Malorie flees to a safe house. Other members of the house speculate that invisible or alien entities are responsible for the outbreak, and the windows are covered in an attempt to protect those inside. Other survivors approach the house — some have seen these “entities” and, instead of killing themselves, attempt to force others to view them as well. Eventually, group members blindfold themselves for safety.

Though invisible, the entities drive Malorie’s pet birds into a frenzy. It is later established that the entities can cause gusts of wind and speak to blindfolded individuals in voices they find familiar, attempting to convince them to remove their blindfolds.

Because the entities are never seen and their method of action is never explained, many “Bird Box” theories have emerged: Characters in the film speculate that ancient demons have found humanity wanting, while others suggest aliens are attempting to conquer the planet.

Alternative Explanation: Mass Psychogenic Illness

Mass psychogenic illness (MPI) offers a potential scientific remedy to this movie madness. Also called mass sociogenic illness, MPI is defined by SAGE Journals as “a nervous system disturbance characterized by the rapid spread of illness signs and symptoms among members of a cohesive social group, for which there is no corresponding organic origin.” In other words, one member of group begins exhibiting strange or dangerous behavior, and others quickly follow.

As noted by Family Doctor, these illnesses have occurred for hundreds of years around the world but are often poorly documented. Common symptoms include:

• Headache
• Dizziness
• Faintness
• Weakness
• Feelings of choking

Often, these illnesses have environmental “triggers” — smells, sights or sounds that make members of a group believe they are in danger. Combined with sudden physical reactions from the initial observer, mass psychogenic events can quickly spread across large groups.

Cultural Impact

Several notable instances of MPI have been documented, including the infamous “Dancing Plague” of 1518. As noted by Ozy, a woman named Frau Troffea began manically dancing in the streets of Strasbourg and wouldn’t stop. Others joined her over the following weeks, and some died when they refused to stop for food or water.

MPI also appeared more recently. According to the New England Journal of Medicine, in November 1998, a high school teacher in Tennessee noticed a “gasoline-like” smell and quickly displayed signs of headache, nausea, shortness of breath and dizziness. Over the next few days, hundreds of staff and students were hospitalized with similar symptoms, but no physical cause was found despite extensive government investigations.

NCBI describes another MPI case: In October 2011, teenage girls in Leroy, New York, all developed “facial tics, muscle twitching and garbled speech.” Folk theories attribute the cause to a local dump releasing toxic fumes, but no definitive cause has been identified.

Thinking Outside the Box

Could mass psychogenic illness account for the mass hysteria and suicidal behavior seen in “Bird Box”? Some of the basic framework certainly applies — i.e., humans living in social groups exposed to sudden behavioral changes related to environmental stimuli.

If we accept the film’s narrative conceit, however, the theory of MPI becomes harder to defend. Some of those exposed to the stimuli exhibit physical changes; those who don’t commit suicide display modified irises, which other survivors check for prior to granting safe house entry. It’s evident that other animals can sense the presence of the stimuli. While gusts of wind could be misattributed to intention rather than random physical phenomena, when characters in the film hear a voice encouraging them to remove their blindfolds, the voice is shown as external and malicious rather than as internal narrative.

Last but not least is the problem of free will. While MPIs can cause observable physical effects such as nausea, muscle twitching and shortness of breath, there’s no indication that they can cause overwhelming suicidal thoughts or remove free will. While some of those afflicted with the Dancing Plague did refuse to stop and eat, many survived by taking breaks at night and resuming the next day. The core concept of “Bird Box” rests on the idea that whatever force — alien, demon or biological agent — is present in this fictional universe can cause people to experience thoughts of such intensity and despair that they choose to end their own lives rather than live with what they see. No recorded MPIs include this type of forced action compelled by overwhelming emotion.

Flight of Fancy

Bottom line? While characters in “Bird Box” display some of the characteristics associated with mass psychogenic illnesses, the physical changes caused by observed stimuli and the sudden, intrusive nature of suicidal thoughts make it likely that a far more fictional — and sparsely defined — threat accounts for this terrifying world of blindfolds and birds.

If you’re experiencing suicidal feelings, get help: Call the National Suicide Prevention Lifeline at 1-800-273-8255 or IMAlive at 1-800-784-2433.