Dr. Matthew Walker

I told you that when you are in REM sleep and you're dreaming, the next day you are better able to assimilate and associate memories and come up with these creative insight solutions.

It turns out that sleep is necessary for that, and not just sleep, but dream-related sleep, REM sleep is necessary for that, but it's not sufficient.

You not only have to be asleep and dreaming to get those benefits, you also have to be dreaming of the very things

that you are trying to solve the next day.

There's a great study by a scientist called Robert Stickgold at Harvard, and he had a whole group of individuals learn a virtual maze, and they were dropped down in different locations of the maze, and they had to try to get out of the maze.

And gradually, when you're dropped down in different locations, you do that enough times, you start to build up this mental map of the maze.

And then he let one half of those participants take a 90 minute nap and the other half remained awake.

And then some hours later, they tested them on the maze and they measured how quickly were you able to navigate and get out of the maze.

That was the outcome measure.

And sure enough, just as we described, those people who slept versus those who didn't, they were better able to navigate the maze after they had slept versus those who remained awake.

But then they went back and they separated those individuals who were napping into two classes, because as they were napping, they were waking them up intermittently and getting dream reports from them.

And what they found was that those people who slept

and still had dream reports, but those dreams were not related to the maze, they didn't show an improvement.

But those individuals who slept and who dreamt, but also dreamt of the specific maze elements themselves, they were the only subset of people, of participants, who showed the benefit.

And that's a beautiful demonstration that yes, you need to sleep to get creative benefits, and in fact, seemingly have dream sleep, but you also need to be dreaming about specific things.

Is that rule true for the second function of REM sleep dreaming, this overnight therapy benefit?

Yes, it does seem to be true.

There were some great studies by a scientist who has sadly passed away now, Rosalind Cartwright,

And she was looking at different patient populations who had undergone really painful, difficult emotional experiences.

For example, a very bitter, painful divorce.