Links Between Epileptic Activity, Sleep Disruption and Mental Content During Sleep

Interactions between epilepsy and sleep are numerous and bidirectional. Sleep can facilitate epileptic activity and seizures in several syndromes, while sleep deprivation increases cortical excitability and seizure susceptibility. Conversely, sleep disturbances are highly prevalent in patients with epilepsy (PWE). Using simultaneous stereoelectroencephalography (SEEG)-polysomnography, the investigators previously showed that sleep fragmentation in focal drug-resistant epilepsy is associated with both ictal and interictal epileptic activity, with increased interictal epileptiform discharges (IED) immediately before and during arousals. However, causality remains unclear, as sleep instability itself may promote epileptic discharges. Determining whether nocturnal seizures and IED directly induce awakenings is clinically important. Nocturnal epileptic activity is often considered less disabling than daytime seizures and rarely guides treatment decisions, yet demonstrating a direct impact on sleep continuity could support therapeutic strategies specifically targeting nocturnal epileptic activity to improve sleep quality. Beyond sleep continuity, epilepsy may also influence cognitive processes during sleep, including subjective sleep depth and dreaming. While the cognitive consequences of epilepsy during wakefulness are well established, relationships between epileptic activity, sleep architecture and subjective sleep experiences remain poorly understood. In a survey of 300 PWE, the investigators observed altered dream recall frequency and dream content, with seizure-related dreams associated with nocturnal seizures. However, retrospective morning reports cannot establish temporal relationships between epileptic discharges and dream phenomena, nor determine the influence of discharge localization or sleep stage. SEEG combined with direct electrical stimulation (DES) provides a unique framework to address these questions. DES is routinely used during presurgical evaluat