Eye movements in REM sleep mimic gazes in the dream world: Multiple brain regions coordinate to conjure wholly imagined worlds

When our eyes move during REM sleep, we’re gazing at things in the dream world our brains have created, according to a new study by researchers at UC San Francisco. The findings shed light not only into how we dream, but also into how our imaginations work.

REM sleep — named for the rapid eye movements associated with it — has been known since the 1950s to be the phase of sleep when dreams occur. But the purpose of the eye movements has remained a matter of much mystery and debate.

“We showed that these eye movements aren’t random. They’re coordinated with what’s happening in the virtual dream world of the mouse,” said Massimo Scanziani, PhD, senior author on the study, which appears in the Aug. 25, 2022, issue of Science.

“This work gives us a glimpse into the ongoing cognitive processes in the sleeping brain and at the same time solves a puzzle that’s triggered the curiosity of scientists for decades,” he said.

Connecting Eye Movement with Dream Direction

In the second half of the 20th century, some experts hypothesized that these REM movements may be following scenes in the dream world, but there was little way to test it, and the experiments that could be done (noting a dreamers’ eye direction and then waking them up to ask where they were looking in the dream) provided contradictory results. Many researchers wrote off REM movements as random actions, perhaps to keep the eyelids lubricated.

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