This is a particular feature of electrical status epilepticus during sleep (ESES), which is characterised by spike and wave discharges in 85–100% of NREM sleep. 7,9Ĭertain epileptic encephalopathies also show marked diurnal variation in seizure manifestation and electrographic activity. 10 Although temporal lobe epilepsy does not show this diurnal variation, if temporal lobe seizures occur during the night, they are more likely to be secondary generalised. 8,9 Similarly, seizures in benign focal epilepsy with centrotemporal spikes (BECTS) show a predilection for sleep or drowsiness. 7 Nocturnal seizures occur throughout all stages of NREM sleep and are distributed proportionately, so that they occur more frequently during light stages rather than deep stages (see Figure 2). In particular, nocturnal seizures are typical of frontal lobe epilepsy, in which seizures usually cluster and can occur many times in a night. 5,6 Importantly, the occurrence of seizures predominantly during sleep is a characteristic of specific epilepsy syndromes. 4 Later studies from the 19th and early 20th centuries determined that 20% of patients with epilepsy have nocturnal seizures only. Indeed, Aristotle stated that “the beginning of this malady takes place with many during sleep, and their subsequent habitual seizures occur in sleep, not in waking hours”. 3 It is also striking that, in some people, seizures can occur exclusively at night, an observation mentioned in ancient texts. This is especially evident in the myoclonic jerks and tonic–clonic seizures in juvenile myoclonic epilepsy. Perhaps the best established relationship between epilepsy syndromes and sleep is in idiopathic generalised epilepsy syndromes, in which seizures occur shortly after waking. Temporal Association of Epilepsy with Sleep Moreover, nocturnal epileptic seizures can be misdiagnosed as sleep disorders and vice versa. lack of sleep can precipitate seizures and seizures can disrupt sleep). Epilepsy and sleep have an important temporal association and can interact (i.e. 2 Since different conditions occur in different sleep stages/states, the timing of events during the night is important for diagnosis. As sleep progresses, deep sleep periods become shorter and are absent towards the morning conversely, REM sleep time increases. NREM can be subdivided into light (stages I/II) and deep (stages III/IV) sleep (see Figure 1). These sleep states cycle over 90 minutes throughout the night. 1 Sleep can be broadly divided into rapid eye movement (REM) sleep and non-REM (NREM) sleep. However, the advent of electroecephalography (EEG) has expelled this misconception and sleep is now recognised as consisting of active brain states during which many biological processes occur, such as synaptic plasticity and memory consolidation. Throughout the ages, sleep has been considered akin to death indeed, Homer referred to sleep as the ‘brother of death’. Keywordsįrontal lobe epilepsy, nocturnal seizures, non-rapid eye movement parasomnia, sleep apnoea, sleepwalking, night terrors Article: Schemes have been developed to facilitate differential diagnosis, although this remains a challenge even using the gold standard, video-electroencephalography telemetry.Īcknowledgements: This work was undertaken at University College London Hospitals/University College London, which receives a proportion of funding from the Department of Health’s National Institute for Health Research Biomedical Research Centres funding scheme. Nocturnal epileptic seizures may be difficult to differentiate from parasomnias, in particular non-rapid eye movement parasomnias such as night terrors, sleepwalking and confusional arousals, on history alone since there are semiological similarities between the two disorders. Conversely, epilepsy and antiepileptic medication can worsen sleep disorders. Sleep disorders such as obstructive sleep apnoea can worsen epilepsy, with improvement of seizure control following appropriate treatment of the sleep disorder. Excessive daytime sleepiness is common in patients with epilepsy and may be due not only to medication but also to nocturnal seizures or concomitant sleep disorders. In some epilepsy syndromes, seizures occur predominantly (or even exclusively) during sleep or on awakening. There is a close association between sleep and epilepsy.
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