In a recent experiment from the University of Bern in Switzerland, a team of scientists invited skilled lucid dreamers to sleep in a specially equipped sleep lab. The purpose of the study was to find out how time passes while we sleep, so the dreamers were asked to perform various kinds of tasks in their dreams.

Once they had gained lucidity, they had to walk 10 paces, count to 30 or perform an elaborate gymnastics routine, for instance. To time the duration of their actions, the scientists used a peculiar aspect of the dreaming mind: although the body is paralyzed, eye movements tend to be translated to the body. In this way, the subjects could signal the start and end of the actions by rolling their eyes left and right a couple of times. Along the way, Erlacher measured their brain activity and muscle movements, to be sure they weren't just pretending to be asleep.

As he expected, the dreamers sometimes took up to 50% longer to complete the routines than you would in real life, suggesting that they were somehow playing out their tasks in slow motion, even though they didn't realize it at the time. “They reported that it felt exactly the same as in wakefulness,” says Erlacher.

Lucid Dreaming Solves Mystery Of Whether Our Brains Go Into Slow Motion When We Sleep

BBC - Future - Do dreams occur in slow motion?