Epilepsy and sleep disturbance

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Abstract

Sleep disturbance is common in epilepsy, the nature of sleep disturbances in epilepsy is diverse, and the etiologies are complex. Evidence suggests that having epilepsy and the occurrence of seizures, as well as some AEDs, are associated with significant sleep disruption. The occurrence of seizures can have profound effects on sleep architecture lasting much longer than the postictal period. Persistent daytime drowsiness in patients with epilepsy is not always due to the side effects of some AEDs and may be independently linked with sleep fragmentation. Significant sleep disruption in epilepsy has been associated with impaired quality of life and impaired seizure control. All aspects of sleep medicine are important in the management of epilepsy and are confounded by the occurrence of seizures, the location of seizures, and the beneficial and detrimental effects of AEDs. Sleep should be proactively evaluated, and sleep disturbances should be treated as part of the total care of patients with epilepsy.

Introduction

Ineffective or inadequate sleep is common in epilepsy patients. Although our society tends to accept poor sleep as the norm, it can result in considerable impairment of daytime functioning and quality of life even in people without chronic illnesses. In patients with epilepsy, the consequences are potentially more severe than among those without epilepsy. Inadequate sleep can exacerbate daytime drowsiness and memory dysfunction, which are common to this group, and can contribute to intractable seizures. Of even more concern is the potential for a continual cycle of sleep disruption, worsening seizures, and further impairment of sleep that can be responsible for intractability of epilepsy in some patients. Despite this, many treating physicians overlook the potential for treatable causes of sleep disruption in patients with epilepsy with the result that optimal outcome may not be achieved.

The causes of sleep disturbance in epilepsy are many and include factors that are also relevant to the general population, such as insufficient sleep, inadequate sleep hygiene, coexisting sleep disorders, and circadian rhythm disturbances. Furthermore, in epilepsy, evidence suggests that the very presence of epilepsy itself can disrupt sleep, and even more evidence shows that seizures themselves can disrupt sleep, even when they occur during wakefulness. A further complication in the management of sleep disruption in epilepsy is that anticonvulsant drugs can alter sleep, both beneficially and detrimentally, and these effects appear independent of their anticonvulsant actions.

In this article, the potential causes of sleep disturbance are reviewed with an emphasis on those that are most common in patients with epilepsy. The impact of these disorders is discussed, followed by a review of the potential impact of anticonvulsant drugs. Attention to sleep should be an essential part of the total care of patients with epilepsy.

Section snippets

Potential causes of sleep disruption in epilepsy

Several studies have confirmed that sleepiness and sleep disorders are common in epilepsy. De Haas et al. showed that patients with partial epilepsy have twice the prevalence of subjective sleep disturbance over the last 6 months as controls (39% vs 18%) and that the presence of sleep disturbance is associated with further significant worsening of quality of life beyond that attributable to just having epilepsy (which was significantly worse than that of matched controls) [1]. In addition, this

Effect of sleep, sleep deprivation, and sleep disruption on the occurrence of seizures

The amount of baseline rhythmicity occurring in the brain differs considerably between the states of sleep and wakefulness. It is, therefore, not surprising that various seizure types begin preferentially in specific sleep states. Crespel et al. [12] specifically examined the occurrence of frontal and temporal lobe seizures in 30 patients, using 5 days of continuous video EEG monitoring. Sixty-one percent of frontal seizures began during sleep, compared with only 11% of temporal lobe seizures.

Other effects of sleep disruption on patients with epilepsy

In addition to the influence of seizure occurrence, patients with epilepsy are probably even more susceptible to the cognitive and functional consequences of sleep disruption than are the general population. The most obvious aspect of this is daytime drowsiness, which may, in part, be related to some domains of cognitive impairment. This is not a trivial problem, as daytime drowsiness contributes to increases in accidents and, particularly in the case of motor vehicles, to fatalities. Patients

Effects of anticonvulsant medications

A caveat to reviewing the effects of AEDs on sleep structure is that although there have been many studies, effect sizes are variable and are often not well defined. Large, prospective, well-designed studies are lacking in this area, despite our knowledge that AEDs can influence sleep. Early studies of the older AEDs showed an increase in sleep stability with all agents. In retrospect, much of this effect was likely due to a reduction in seizure activity, rather than an independent, beneficial

Conclusions

Attention to sleep in patients with epilepsy has important implications for diagnosis, seizure control, and quality of life. It is clear that independent sleep disorders frequently coexist with epilepsy and that seizures themselves cause sleep disturbance. The common complaint of daytime drowsiness can no longer be dismissed in patients with epilepsy, in whom sleep studies and diagnosis can clearly improve both seizure control and sleep. Any patient with persistent daytime drowsiness should,

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