Sleep Study Made People Sleep With One Eye Open and Found Unexpected Brain Activity

Researchers from Switzerland conducted a study wherein they made people sleep with their eyes open. The goal of the study was to find out just what is going on behind our eyelids as we slumber and how that correlates to our brain activity.

The researchers found that our pupil movements reflect different levels of brain activation. And there was a lot more activity than they suspected there would be.

We used to assume that our brains mostly shut down when we were asleep, Caroline Lustenberger and her team at ETH Zürich can safely say otherwise. They focused their research on the locus coeruleus, the part of the brain that regulates sleep and wakefulness, to find out if “the level of arousal during sleep is low” as was previously suspected.

To Study Our Pupils As We Sleep, Researchers Forced People To Sleep With One Eye Open

She and her team tested this by tracking changes in a pupil as a person sleeps. Doing so required keeping a person’s eye pried open as they slept. Now you’re wondering how they pulled that off. You’re probably also imagining some fanciful sci-fi technology that can suspend an eyelid open while simultaneously blocking out light from the pupil.

Nope. While the technique they used wasn’t exactly like that scene from A Clockwork Orange, its low-tech approach wasn’t too dissimilar.

They applied an ointment containing vitamin A before the eye was covered to keep it moistened. They then taped open one eye and put a bandage over it that had a hole cut out in the middle that contained a little plastic observation window so the researchers could keep track of pupil movement.

If you’re wondering how the participants managed to fall asleep with one eye open, they just could. The text of the study doesn’t discuss any special technique or technology used to get the participants to fall asleep.

It simply says, “All participants could tolerate having their eyes taped open and were able to fall asleep.” Who were these super soldiers who could very literally sleep with one eye open?

Now for the actual scientific observations that resulted from all of that eye torture: The researchers found that pupil size fluctuates a ton when we sleep, and those shifts correspond to our brain activity.

Specifically, the interplay between pupil and brain was linked to specific sleep patterns, like brain patterns that deal with our memories and patterns that maintain our ability to sleep as we sleep.

The researchers suspect that their work might one day be used as a diagnostic tool for sleep disorders and maybe even posttraumatic stress disorder.