According to “The Brain’s Dark Energy” by Marcus E. Raichle, neuroimaging shows that a human brain is always very actively messaging, even when daydreaming, asleep or anesthetized, and that the marginal energy consumption for consciousness is only 5%.
According to Lisa M. Krieger, interviewing physicist Andrei Linde
This most extraordinary of ideas was conceived in the most ordinary of circumstances. Linde was lying in bed, sick, at his home in Moscow, during a miserable winter. And his international intellectual life was in limbo, because publication of a paper had been suspended a year during the turbulence at the end of Soviet rule.
“I was living in this state of depression. I was in my bed and unable to do anything,” he said. Then came a sudden invitation to visit Italy — but he had to submit a paper overnight.
“I held my head … What can I do? What can I do?” he recalled thinking, with less than an hour to write. “And suddenly, I had the theory of eternally expanding inflationary universes, unceasingly producing new universes,” of which ours is but one of many.
“It was just pure, from nowhere,” he said.
See also “Keep thinking, think of it everyday“.