For many patients with epilepsy, sleep plays an integral role in their disorder. The dynamic state of sleep offers unique diagnostic and therapeutic opportunities for diseases of the central nervous system, such as epilepsy. Sleep encompasses neurophysiological states that may reveal aspects of epilepsy that are not readily apparent in wakefulness. Sleep deprivation is accepted as a provocative agent for seizures and epileptiform activity. In addition, the treatment of sleep disorders may provide beneficial effects to the brain to improve the control of seizures and quality of life. Beyond sleep, the circadian rhythm may influence the timing of seizures and medication pharmacokinetics and effect. Epilepsy and its treatment may also influence sleep. Epileptic discharges can change the brain’s sleep regulatory mechanisms, increasing shifts in sleep stages and arousals. Moreover, the treatment of epilepsy may alter the brain’s sleep regulation.
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• Patients with epilepsy frequently complain of sleep issues.
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• Excessive daytime sleepiness may be related to sleep deprivation, sleep disorder, epilepsy-related sleep disruption, or effect of medication.
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• Insomnia may be related to poor sleep hygiene, a comorbid sleep disorder, epilepsy-related sleep disruption, or effect of medication.
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• Ictal and interictal discharges may disrupt sleep and the regulatory processes associated with sleep.
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• Treatment of sleep disorders may improve epilepsy, and epilepsy may improve sleep.
Historical note and terminology
Aristotle noted that “sleep is like epilepsy and epilepsy is like sleep.” This relationship and comparison drives to the heart that both are states of altered awareness as dictated by brain function (21). Sleep is a normal physiological state that helps rejuvenate the brain, whereas epileptic seizures are a pathological state associated with a variety of negative outcomes. Galen also noted that patients with epilepsy should be cautioned to get enough sleep (48). In 1880, Gower classified patients with epilepsy into three groups: those that had seizures only in sleep, those that had seizures only when awake, and those with diffuse epilepsy (37). He also recognized that over time, patients would transition from sleep- or wake-dependent seizures into those with diffuse epilepsy. Janz furthered our understanding of the relation of sleep-related epilepsies by defining that most sleep-related seizures appear to come from the frontal and temporal lobes (25). From these early observations, we have come to understand that sleep has an influence on epileptic seizures and that sleep deprivation can be used as a clinical tool to unveil features of epilepsy.
The potential of improvement in sleep with the treatment of epilepsy was demonstrated by Touchon and colleagues, who showed that the use of carbamazepine reduced the number of arousals and improved sleep efficiency (49). The corollary that treatment of sleep disordered breathing may help epilepsy has been shown by multiple authors that laid the foundation for further work, examining the relationship and clinical impact of sleep in epilepsy.