Sleep and Epilepsy

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Sleep and epilepsy are common bedfellows. Sleep can affect frequency and occurrence of interictal spikes and occurrence, timing, and threshold of seizure. Epilepsy can worsen sleep architecture and severity of sleep disorders. Thus, a vicious cycle is set. Certain epilepsy syndromes are so intertwined with sleep that they are considered sleep-related epilepsies. Poor sleep in epilepsy is multifactorial and is worsened by poorly controlled seizures. On the contrary, poor sleep is associated with worsened quality of life, psychological function, and memory. Improving sleep has been noted to improve seizure frequency and an overall well-being in patients with epilepsy. Hence, an emphasis should be given to address sleep in patients with epilepsy. These interactions are discussed in detail in this review.

Introduction

Epilepsy affects 1% of the population in the USA.1 Occurrence of 2 or more unprovoked seizures, more than 24 hours apart, or a single unprovoked seizure (reflex seizure) with at least 60% chances of recurrence or diagnosis of an epileptic syndrome defines epilepsy.2 The tendency toward seizures or epilepsy is measured by an electroencephalogram (EEG). EEG abnormalities in between seizures are called spikes or sharp waves or interictal epileptiform discharges (IEDs). Electrographically, seizures can be identified by distinct, rhythmic, epileptiform patterns that disrupt the normal EEG background, evolve in amplitude and frequency, often spread to involve other brain regions, and end abruptly. Despite advances in localizing seizures, new devices, and several new medications, epilepsy remains incurable in a fraction of patients. Significant comorbidities have also been reported, one of which is coexisting sleep disorders.

Sleep and epilepsy are interrelated. The importance of sleep in epilepsy is well known since the ancient times. Aristotle wrote that sleep is similar to epilepsy and in some way epilepsy is to sleep. In 1885, Gower described that 21% of children had nocturnal seizures. He also reported that nocturnal seizures occurred at specific times in sleep. Ferri et al described that seizures affected sleep.3, 4, 5 The effects of sleep and epileptiform discharges were first described by Gibbs and Gibbs in 1947.3, 4, 5 Here we review how sleep affects epilepsy and vice versa.

Section snippets

Effect of Sleep on EEG, Seizures, and Epilepsy

Sleep is well known to activate IEDs by non-rapid eye movement (NREM) sleep in adults with focal epilepsy. The spike frequency increases with increasing depth of sleep and is significantly reduced in REM sleep.6, 7 The field of discharges also expands in sleep with more diffuse discharges during N3 and restricted field during REM.8 Owing to both of these phenomena, IEDs occurring in REM often help to lateralize seizures.9, 10 Studies in children showed that some children may have spikes only

Sleep-Related Epilepsies

A distinct, syndrome-specific pattern of seizure frequency or EEG pattern is seen in certain epilepsy syndromes. Patients with generalized tonic-clonic seizures on awakening have generalized seizures that occur in the morning. Juvenile myoclonic epilepsy is characterized by myoclonic, absence, and generalized tonic-clonic seizures. Myoclonus occurs soon after awakening, which may progress to a generalized seizure. Other syndromes are described in the following sections.

Effect of Seizures and Epilepsy on Sleep

A seizure occurring in sleep causes significant reduction of REM sleep, sleep efficiency, and increases N1. If the seizure occurs before the first REM cycle, the REM sleep and sleep efficiency are further reduced. Decrease in total sleep time owing to reduced REM sleep and increased wake times have also been reported.39

Effect of AEDs on Sleep

A recent paper reviewed 45 studies describing the effects of AEDs on sleep architecture.40 Phenobarbital, phenytoin, and gabapentin reduced sleep-onset latency. Phenobarbital and gabapentin also reduced arousals from sleep. Pregabalin, carbamazepine and gabapentin increased slow-wave sleep (N3) whereas levetiracetam and ethosuximide reduced it.

Phenobarbital and phenytoin reduced REM sleep whereas ethosuximide and gabapentin increased it. On objective sleep measures like multiple sleep latency

Sleep Disorders in Epilepsy and Effect of Treatment of Sleep Disorders on Epilepsy

Sleep disorders are common in epilepsy, and many of them have a higher prevalence in patients with epilepsy than in the general population.

Sudden Unexpected Death in Epilepsy, Sleep, and Cardiorespiratory Abnormalities

Sudden unexpected death in epilepsy is defined as a “sudden, unexpected, witnessed or unwitnessed, non-traumatic and non-drowning death in patients with epilepsy with or without evidence for a seizure and excluding documented status epilepticus in which postmortem examination does not reveal a toxicologic or anatomic cause for death.”66 The incidence is as high as 6.0-9.3 per 1000 patient-years among patients evaluated for or treated with epilepsy surgery or vagus nerve stimulation for epilepsy.

Other Associations with Sleep and Epilepsy

Anxiety and depression in adults and behavioral problems in children with epilepsy are common. Studies suggest that these problems are even worse when sleep disturbances or disorders are associated.29 In a recent study, suicidal ideation was also linked to poor sleep quality in patients with epilepsy.69 Additionally, patients with epilepsy and sleep problems have poorer quality of life as compared with patients without sleep problems.70, 71, 72 Other studies have shown that children with sleep

Conclusion

Despite this compelling evidence for improving quality and quantity of sleep, a recent study showed that more than a third of the patients with epilepsy slept 6 hours or less.76 Moreover, a study evaluated sleep screening practices of neurology providers who had referred patients for sleep evaluation. The results showed that 94% of the providers used routine sleep screening, but only 30% asked detailed questions about sleep.48 Similarly, pediatricians used 1-4 questions, which pertain to

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