Sleep fragmentation and decreased REM sleep in a primate model of diurnal cortical seizures

Many people with epilepsy suffer from comorbid sleep disorders and sleep fragmentation. While the disruptive nature of seizures on sleep is well documented, it is unclear how diurnal seizures impact sleep quality and for how long these changes persist during the following nights. To better understand this relationship, the sleep architecture of two rhesus macaques were studied before and several nights after penicillin-induced diurnal seizures. These focal seizures stopped naturally, and none occurred at night. We scored sleep-stage during the nights immediately following the seizures, as well as several nights after seizure induction. We noted a significant increase in movement along with a decrease in sleep efficiency, both limited to the night of seizure induction. For both animals, we observed a significant decrease in the number of REM periods that manifested as a decrease in total REM sleep duration, and this phenomenon persisted up to 2 nights after the seizures. We also found a significant increase in the probability to transition from stage N2 to stage N1 on the night of the seizures. This study shows for the first time that the NHP model of penicillin-induced cortical seizures exhibits significant changes in sleep architecture, including an increase in nocturnal movement, change in sleep architecture and a prolonged decrease in REM activity. The prolonged decrease in REM periods compared to the temporary enhanced movement and reduction of sleep efficiency suggest that these seizures may affect two neural circuits, one controlling REM sleep entry and the other controlling nocturnal wakefulness.