How Dreams Change From Infancy to Old Age

Dreaming is a distinctive state of consciousness during sleep that is generated by specific neural circuits. Perceptual imagery, usually only visual and auditory, is generated in the absence (generally) of sensory input. Dreaming occurs predominantly during rapid eye movement (REM) sleep; dream recall estimates following REM sleep are about 80%. In contrast, dreaming is reported less than 10% of the time after awakening from non-rapid eye movement (NREM) sleep. Therefore, different sleep stages likely support dreaming.

The functional relevance of dreaming has been a matter of intense debate over many decades. In order to determine the purpose of dreams, scientists have catalogued their characteristics by waking dreamers and asking them to describe their dreams.

Consistent dream patterns exist

Dreams have vivid visual images and greater emotional content than is usually experienced while awake. We can mind read when dreaming. Dreams are mostly visual; people rarely report the experience of tasting or smelling something (unless they have bipolar disorder). Despite being inside scenes of painful experiences the dreamer does not report feeling pain. Dreams have thematic discontinuities with very quick changes in the plot. One moment we are in Cincinnati, the next moment finds us in Cleveland. Dreams often defy the laws of physics; sometimes we defy gravity and fly. The characters that populate our dreams are both real and fantastical. This is fortunate since we lack any sense of self-reflectiveness while dreaming. Dreams often condense two different people into one person making it difficult to recall whom we were interacting with while dreaming. Some things are rarely or never part of dreams, such as reading, writing, arithmetic or reflective thinking. Overall, dreams are full of metaphors and irony.

Dreams are something that the brain finds necessary. When REM sleep is reduced due to medication or sleep deprivation, the amount of time devoted to REM is increased during the next sleep period and the dreams are more vivid and abundant. This is called REM rebound. Dreams allow us to easily make disparate connections between otherwise unconnected concepts that promote creativity and problem-solving during the day.

Dreams across the lifespan

The changing characteristics of dreams as we progress from childhood to old age offer insight into the purpose of dreams. During the second trimester of fetal growth, brains appear to be in active sleep mode most of the time. This state resembles REM sleep. The dreams of toddlers are static scenes of family members or animals. Toddlers report that they believe that dreams come from outside of themselves. During childhood, ages three to seven, dreaming is more frequently reported, and the dreamer has a clearer representation of self. Nightmares also start to appear at this age.

Between seven to 12 years of age dreams become more elaborate and involve friends and unfamiliar characters outside of the family. Between 12 and 16, after puberty, dreams become elaborate and vivid, animals disappear and “wet” dreams with attachments to romantic objects and people occur. Sleep is most restful at puberty. After puberty, sleep quality begins to deteriorate and continues to do so until old age. Between 14 and 19, dreaming becomes even more elaborate and is full characters, both familiar and strange and romantic. Males experience increased physical aggression during their dreams; females experience more verbal aggression.

During adulthood, for women until menopause and men into senescence, dreaming remains elaborate and involves everyday social interactions. Male and female differences are present. For example, men report not knowing the identity of their sexual partners and often do not report seeing the face of their sexual partners. Women usually know their sexual partners and often report seeing their hands. Women are more likely to report bright colorful dreams while men report fewer or no colors. During senescence, men and women report more reflective dreaming with scenes of loved ones both living and dead. Dreams that occur near death tend to be more spiritual, epic and reflective and more often involve loved ones who have died.

What brain regions influence dreaming?

Scientists have noticed the critical role that increasingly complex social interactions play in dreams. The current best hypothesis suggests that dream content depends on the maturation of the “social brain network” that includes (these are rough generalizations) the amygdala (critical for emotion), fusiform gyrus (facial recognition), prefrontal cortex (theory of mind), superior temporal gyrus (mirror neurons), the temporal-parietal junction (theory of mind), posterior cingulate (self-awareness and time-traveling) and hippocampus (for the memories). [For more information on the function of these brain regions, see here.] Two neurotransmitters that are known to be involved in social interactions while awake, oxytocin and vasopressin, are also important while dreaming. Oxytocin enhances our level of trust and emotional closeness while vasopressin may be involved in social memories, especially in males.

Brain structures devoted to navigating complex social interactions, influenced by maturational and hormonal changes during the lifespan, undergo patterns of activation and deactivation that determine the changing features of our dreams. The precise role of each brain region and the reasons that our brain appears to require dreaming for our mental and physical health remain to be determined. But first, it is time to take a nap and dream.