The interplay between sleep and cognition in adults with Epilepsy: evidence from a systematic review

Sleep disturbances and cognitive impairment are common among people with epilepsy (PWE). The relationship between sleep and epilepsy has been studied extensively and considered bidirectional, but the mechanism behind cognitive problems remains unclear. Prior research has demonstrated the benefit of sleep on cognition in healthy individuals. In turn, studies investigating whether sleep disturbances could be causing cognitive impairment in PWE have been performed but these are few, mainly focusing on paediatric patients. We conducted a systematic review of studies published between 2000-2025, aiming to identify correlations between sleep (macro-architecture and self-reported sleep quality) and cognition in adult PWE. Risk of bias and quality were assessed. Thirteen studies passed the exclusion criteria with data from 581 patients. Nine studies identified significant correlations between at least one sleep parameter and cognitive function. Four studies investigating sleep-dependent memory consolidation demonstrated a retained benefit of sleep on memory in PWE. Four studies found that sleep microstructure played an independent role. Another finding shared by six studies was the negative effect of nocturnal interictal epileptic discharges (IEDs) on cognition. This effect might disrupt overnight memory consolidation processes, thus limiting the benefit of sleep on cognition, and, in turn, explain why several studies failed to record positive correlations between sleep and cognition. In conclusion, more homogeneous studies with larger cohorts are recommended to establish the exact relationship between sleep macro-architecture and cognition in PWE. Deeper research on the role of sleep microstructure for cognitive function might also provide further insight into this complex and multidirectional relationship.