Multiple Sleep Latency Tests in Epilepsy

Seizure patients often complain of sleepiness or disturbed sleep. Although susceptible of medication effect, the multiple sleep latency test (MSLT) may quantify daytime sleepiness and help to establish whether qualitative sleep disturbance accompanies epilepsy. In order to measure daytime sleepiness in epilepsy patients, 30 patients with newly diagnosed or presently untreated complex partial seizures had MSLT after an overnight sleep EEG that showed no sleep deprivation or nocturnal seizures. Four 20-minute naps were undertaken at 09:00, 11:00, 13:00, and 15:00, and sleep latency was recorded along with 8 channels of EEG. Twenty of 30 seizure patients reported subjective sleepiness. Eight patients had average sleep latencies less than 8 minutes, and 3 had latencies less than 5 minutes. No sleep onset REM or respiratory disturbance was noted. Twenty-five patients had EEG abnormalities but none had ictal seizures. Right temporal epileptiform activity correlated with sleepiness. MSLT may quantify sleepiness in epilepsy patients, which is common but may be subjective or psychophysiological. Some patients with partial seizures have persistent daytime sleepiness independent of medication, possibly related to residual medication effects or non-specific effect of their epileptogenic foci.