Epilepsy is a disorder of recurrent seizures that may consist of subtle changes in attention or even convulsions. Approximately 15% to 30% of people with epilepsy will have sleep seizures, either exclusively or predominately.
Sleep seems to be associated with increased changes in the electrical activity of the brain that are characteristic of seizures. These can be measured with an EEG. These changes, or epileptiform discharges, often occur during NREM sleep and especially during slow-wave sleep. It seems that during REM, the stage when dreaming occurs, these discharges are suppressed and the abnormal electrical activity affects less of the brain.
What Epilepsy Disorders Are Associated with Sleep Seizures?
There are a handful of specific epilepsy disorders that are closely related to sleep seizures. These include:
- Frontal lobe epilepsy
- Temporal lobe epilepsy
- Juvenile myoclonic epilepsy
- Benign childhood epilepsy with centrotemporal spikes
- Epilepsy with generalized tonic-clonic seizures on awakening
What Are the Consequences of Sleep Seizures?
When seizures do occur at night, they can lead to increased awakenings and the fragmentation of sleep. This leads to more of the night being spent in lighter sleep stages and a decreased amount of REM sleep. As a result, a person who has sleep seizures may experience excessive daytime sleepiness.
Conversely, sleep deprivation can profoundly affect one's tendency to have seizures. Not getting enough sleep lowers a person's seizure threshold, meaning that it becomes easier to have seizures. Since this occurs because of an increase in the frequency of the abnormal electrical discharges in the brain, sleep deprivation is often used to diagnose epilepsy.
Curiously, individuals with medically refractory epilepsy -- meaning that they continue to have seizures, despite optimal medication compliance -- frequently have sleep apnea, in up to 30% of cases. They are more likely to have seizures compared to individuals with a similar epilepsy disorder but without sleep apnea. The good news is that treatment of the sleep apnea tends to lead to better seizure control.
How Can Epilepsy Medications Affect Sleep?
Medications that are commonly used to treat epilepsy may also cause sleep changes. Some may cause excessive daytime sleepiness as a side effect. They include benzodiazepines, carbamazepine, Phenobarbital, topiramate, and gabapentin.
Other antiepileptic medications, such as felbamate, may cause insomnia. It is important to recognize sleep disruption or excessive sleepiness as potential side effects of these medications and bring these issues to the attention of your doctor.
Mowzoon, N et al. "Neurology of Sleep Disorders." Neurology Board Review: An Illustrated Guide. 2007; 744.