The evolution of sex differences in competitive and social dream content

Why do we dream? Evolutionary theories suggest that dreams may confer a fitness advantage by simulating real-world challenges. Simulation-based models suggest that dreams serve adaptive functions, including resolving emotional stress and enhancing readiness for waking encounters. From this perspective, evidence of evolutionary pressures reflected in dream content would support the view that dreaming could serve an evolutionary purpose. We explore whether sex differences in evolved behavioral and cognitive strategies shaped by distinct evolutionary pressures are expressed in dream content. We hypothesized that biological sex influences dream content; specifically, that females would report more dreams featuring social and emotional themes, while males would more frequently report dreams involving competition-related content (e.g., risk, reward, and threat), reflecting sex-differentiated ancestral challenges. With a sample of 298 participants logging 4641 dreams, we evaluated dream content across six thematic domains: Emotional Valence, Positive Emotional Content, Negative Emotional Content, Social Content, Competition-based Content, and Resource Acquisition-based Content. Using a mixed-effects model, we discovered that males were significantly more likely to report dreams involving competitive content, while females showed a higher propensity for social dream content. No other themes, including the domains of emotional content, yielded significant results. While these patterns are consistent with possible adaptive functions of dreaming, they may also reflect hormonal influences, socio-cultural factors, personality differences, or other non-evolutionary contributors. Our results extend existing literature on sex differences in dream content using text-based scoring methods, offering a nuanced perspective on how dreams may relate to both biological and social influences.