Abnormal sleep in patients with epileptic or dissociative (non-epileptic) seizures: a polysomnography study

The aim of this study was to identify the prevalence of sleep disorders and measure the objective sleep quality in patients with seizure disorders.

Patients admitted for video electroencephalography monitoring were prospectively recruited and polysomnography was performed on the third night of monitoring.

A total of 4/44 (9%) patients with epilepsy and 2/22 (9%) patients with dissociative seizures were found to have mild sleep-disordered breathing. Three (7%) patients with epilepsy were found to have mild or moderate obstructive sleep apnea-hypopnea syndrome (OSAHS) and three (14%) patients with dissociative seizures had mild or moderate OSAHS. Most patients with sleep-disordered breathing or OSAHS were overweight or obese. Time awake after sleep onset was high in both groups. There were no significant differences in sleep architecture between the groups except for a difference in average N3 sleep stage proportion. Periodic limb movements (PLMs) were common in both groups and 27% of patients with dissociative seizures had both high PLM rates and high arousal indices, suggesting a high prevalence of probable PLM disorder in that group (compared with 9% in the epilepsy group).

Our findings contradict the commonly reported high comorbidity of OSAHS and epilepsy, and question its purported clinical relevance. High rates of PLMs were found in patients with dissociative seizures. In both patient groups, high awake after sleep onset times were indicative of sleep disruption, which can have an epileptogenic effect and is known to increase dissociative tendencies.