How long does it take to dream a dream?

Originally published on March 23, 2019

This week's question comes from Craig Smith and Sara Miller from Toronto, who wonders:

How long does it take to dream a dream (relative to real time)?

We went to research scientist Lia Turner who works in the Imagination Lab at Carleton University.

Turner explains that while dreams seem continuous, they are actually broken down into stages and interrupted as the brain moves through various parts of the sleep cycle.

"The first dreaming session lasts approximately 10 minutes, beginning about 90 minutes after you've fallen asleep. As the sleep cycle continues, the REM (rapid eye movement)  stages increase in duration, with the final dream lasting up to one hour," said Turner.

REM is the part of the sleep cycle our most memorable and vivid dreams take place.

But the difference in the passage of time in a dream state and reality is a complicated problem to study. This is because our judgment in the time passed is subjective and our brain has neurotransmitters to facilitate the waking up process which removes the subjective ability to remember it accurately.

Some insight might come from a study by psychologist Daniel Erlacher, which asked lucid dreamers to complete a simple motor task in a dream state and report how long they believed it took them while being timed in reality.

On average, he found that it took participants about 40 per cent longer in a lucid dream state. This may correspond to regular, non-lucid, nighttime dreaming, but there is no way to be exactly sure.