When Brains Dream: Understanding the Science and Mystery of Our Dreaming Minds: Exploring the Science and Mystery of Sleep

Humans cycle in and out of REM sleep about every 90 minutes, all night long. Occurring between these REM periods are three distinguishable stages of non-REM sleep, called N1, N2, and N3,

These newly discovered periods of “rapid, jerky eye movements,” as Aserinsky and Kleitman called them, were not just related to dreaming. We now know that the brain’s normally careful regulation of a host of bodily functions seems to go offline during REM sleep. Heart rate, blood pressure, and breathing all vary widely during REM sleep. Not only th

Thus, emotionally engaged narrative dreaming is required for the full exploration, evaluation, and strengthening of novel associations relevant to our ongoing concerns. This process, in a nutshell, is the biological function of dreaming.

our original questions—what dreams are, where they come from, what they mean, and what they’re for.

sleep’s role in memory processing, nor about the role that REM and non-REM dreaming might play in these processes. We saw in Chapter 5 that both REM and non-REM sleep contribute to memory evolution. Sleep enhances some memories while allowing others to be forgotten. It processes both emotional and unemotional memories. It enhances some memories in

As you might imagine, almost all REM dreams fall into one of these two categories—90 to 100 percent, depending on the study. In contrast, self-representation is seen in only two-thirds of non-REM dream reports and in somewhere between a quarter and two-thirds of sleep-onset hypnagogic dreams, depending on exactly how long after sleep onset the repo

we also find a sub-network that helps us recall past events and imagine future ones, another that helps us navigate through space, and yet another that helps us interpret the words and actions of others. And these are the mental functions associated with mind wandering.

Take a look at people walking down the street, driving in their cars, eating alone in restaurants and cafes. Not so long ago, these people wouldn’t be doing anything else. Their minds would wander and they would daydream; their DMN would be active, and, although they were totally unaware of it, they would be tagging recent memories for processing l

Our brains are always thinking about something. Because of this, the brain areas that turn off whenever we start to carry out a mental task are the regions that do whatever the brain does when we’re “not doing anything.” Together these regions make up the default mode network (DMN), whose discovery has helped us appreciate just how true it is that