Brain rot in the digital age: Sleep loss, circadian disruption, and neurocognitive vulnerability.

The colloquial expression "brain rot" is increasingly used to describe attentional fragmentation, cognitive fatigue, motivational blunting, and a sense of mental "slowness" after prolonged engagement with high-intensity digital media. In this semi-structured narrative review, we use the term as a heuristic bridge concept rather than a formal diagnosis and examine whether sleep and circadian mechanisms provide a biologically coherent account of these complaints. PubMed and Google Scholar were searched through March 2026, with emphasis on chronobiology, sleep deprivation/restriction, digital media use, reward-heavy platforms, media multitasking, and adolescent development. The strongest direct human evidence supports a proximal pathway from evening or post-bedtime digital exposure to sleep displacement, melatonin suppression, circadian delay, shortened sleep, and next-day attentional and emotional dysregulation. We then review candidate downstream mechanisms involving synaptic homeostasis, cortical excitation-inhibition balance, thalamocortical oscillations, large-scale network instability, and reward-related behavior. By contrast, evidence linking typical digital-media-associated partial sleep restriction to amyloid or tau accumulation remains indirect and should not be interpreted as proof of neurodegeneration. Overall, "brain rot" is best conceptualized as a sleep- and circadian-linked neurocognitive vulnerability state, with particularly high relevance to adolescents and young adults because of developmental phase-delay biology, ongoing maturation of prefrontal executive control, and environmental timing pressures.