Do all animals dream?

Image by Shingo_No from Pixabay

Question from Matt Hart

They all sleep, but they don’t all dream. We can tell when a human is dreaming because their eyes start to move –  that’s why we call dream sleep ‘REM’ – it stands for rapid eye movement. Our brain activity also changes, moving from the slow waves of deep sleep to waves that look much more like they do when we are awake. Looking at the brains of other animals has revealed that mammals and birds dream too. In lab experiments, rats practiced  mazes in their sleep and finches rehearsed songs. But fish and insects don’t seem to dream at all. 

Answered by Laura Mears for Brain Dump in How It Works issue 125.

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