Dreams have provided a source of fascination throughout human history. Ancient Egyptians viewed them as messages from the divine; Aristotle believed they could be used to diagnose illnesses; and Freud considered them a window into the subconscious.

For such an ubiquitous and widely studied phenomenon, however, dreams remain stubbornly mysterious. Why we dream and how our brains shape the content of our dreams remain largely unknown, while the few things we do know through studies—that we tend to dream about things that happen in our lives, and that most often those things have occurred relatively recently, for example—often seem obvious.

"What we can confidently say we know about dreams is actually very little," says Caroline Horton, a senior lecturer in psychology at Bishop Grosseteste University in England. Because the content of dreams cannot be externally validated, it can be challenging to collect data on them or draw any definitive conclusions about those data. "To study dreams, we have to rely on a person's memory, and we don't really know if what they're saying is true or not," Horton says. "Dream recall is really a gray area."

From what researchers do know, it seems that dreams tend to home in on salient features from our waking life, and that they probably serve to embed important information into our knowledge structure, as the brain goes through its nightly encoding of short-term memories into long-term memory. Evidence is building, however, that not all people dream in exactly the same way, and that individual personality might play a significant role in shaping the contents of our nocturnal psyche. Some studies indicate that people who are more social tend to have dreams involving more characters, for example, while those who suffer from low psychological well-being are more likely to have more recurrent dreams and nightmares. Many of the correlations that studies investigating this aspect of dreaming have uncovered, however, have been quite weak, leading some researchers to question whether they actually represent a connection between personality and dreaming or if they are just a quirk of the data, the analysis or the tendency for subjects to report dreams in a particular way.

In a new study published in the journal Consciousness and Cognition, Josie Malinowski, a lecturer in psychology at the University of Bedfordshire, further explored this subject by asking more than 100 volunteers to write a detailed description about their most recent dream. She also asked them to fill out a "Big Five" personality survey, which measures how extraverted, agreeable, conscientious, neurotic and open to experiences a person is. Finally, she administered a questionnaire meant to reveal how inclined an individual is to try to avoid certain thoughts in her daily life. This form of mental control, called thought suppression, might be used to keep money woes at bay or to banish an ex from our mind. But it can have a paradoxical effect—a finding that was first uncovered 1987 when researchers found that asking participants not to think of a white bear actually caused them to think of a white bear all the more. Some evidence exists that it can also lead to a rebound effect that transpires in dreams; like a game of whack-a-mole, the to-be-forgotten thought simply pops up after the lights go out on the suppressor's waking life.

Crunching her data, Malinowski found that more than half of the participants' dreams revolved around relationships. "Dreams were particularly social experiences," she writes, and they were much more likely to entail interpersonal interactions than dwell on subjects like work, study or finances. But contrary to previous studies, Malinowski uncovered no significant correlations between participants' "Big Five" personality scores and the contents of their dreams.

Thought suppression, however, did turn out to be significantly related to a person's tendency to experience emotionally-charged dreams. In other words, those participants who viewed themselves as having the highest ability to control their conscious emotions seemed to experience the greatest rebound effect in their dreams. "The more participants suppressed their thoughts during waking life, the more they reported dreaming of their waking life emotions [and relationships] in their most recent dream," Malinowski writes. "This could be interpreted in line with Jung's compensation theory of dreaming, such that individuals who fail to think adequately about aspects of their waking life then go on to dream of them."

While this finding is not entirely unexpected, Malinowski's study adds to the growing body of evidence that a correlation exists between a person's propensity toward thought suppression and the content of their dreams. "We're all different, so it's not surprising that we all won't experience the same things at night," Horton says. "Dreaming is an extension of what we're doing in our lives—it just plays out in a slightly more bizarre context."