What Happens in the Brain When We Dream?

Have you ever had a dream so vivid that you thought it was real? Sometimes, dreams resemble so much of our real-life experience that we wish they would last forever. Especially if they involve a trip to Bali!

While some people feel deeply affected by their dreams, there are others who do not think that they even dream at all. However, sleep researchers have argued that we all dream even if we do not remember what we see. The main reason behind this idea lies in the five stages of sleep and the type of brain activity associated with them.

So, what happens in this mysterious dream place we enter every night?

Dreams and REM

Up until recently, researchers thought that dream experiences occurred only in REM sleep. However, latest scientific evidence suggests that dreams can also happen in NREM stages. In fact, people have reported dream experiences in NREM sleep up to 70% of the time.

In a study published in Nature Neuroscience, Francesca Siclari and colleagues confirmed that dreams can occur during any sleep stage. For this study, the researchers investigated both the dreaming experiences of participants and dream content. Regarding dream content, the researchers asked study subjects to rate their dreams on a scale of thought-like (thinking and/or reasoning) to perceptual (vivid images, no reasoning). Moreover, they also analyzed whether dreams contained faces, movement or speech.

Siclari and her colleagues found that there is a “hot zone” region in the brain associated with dreaming. When the parieto-occipital region (a region towards the back of the brain) showed an increase in low-frequency (slow) EEG activity, study participants reported no dreams. However, subjects reported dreams when this hot zone showed a decrease in low-frequency EEG activity. The researchers report that they observed this finding regardless of the type of sleep (REM or NREM) participants were in.

The investigators of the study also found an interesting association between subjects’ dream content and waking perception of the same contents. These findings suggest that dream content (thoughts, perceptions, faces, places, movement and speech) is associated with an increase in fast EEG activity in specific brain areas which resemble activity in awake state.

The researchers suggest that these findings “[provide] further evidence that dream reports reflect conscious experience during sleep rather than confabulations upon awakening.” In other words, what we remember from our dreams are not mere fabrications to fill in the gaps in our memories but reflections of real (neural) experiences.