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EPILEPSYESSENTIALS By Steven Karceski, MD Exploring the Mysterious Link Between Sleep and Epilepsy Nocturnal seizures often go unnoticed or misdiagnosed. Here’s how to stay alert to their signs and symptoms. any of us spend about one third of our lives sleeping (some a little more; physi- cians often get less). It Mseems clear that sleep is essential. When we are sleep deprived, even for short periods of time, we experi- ence troubles with memory, attention, concentration and personality changes. Doctors and nurses know the conse- quences of this well: sleep deprivation, when extreme, can lead to medical errors. This understanding has lead to the limi- tation of resident work hours in certain states like New York. Although we may spend one third of our lives sleeping, we There are many types of nocturnal events that understand the phenomenon poorly. The relationship between sleep and can be mistaken for nocturnal seizures. The history medical illnesses is even less well defined. is critical in making the diagnosis. However, we are starting to learn more about an intriguing connection: recent research has begun to define the link shortly after waking up. Though this not signal an underlying neurological between seizures, seizure medications and association is well known, the reason why problem. For instance, many people have sleep. the seizures have this pattern is unknown. experienced a “hypnic jerk” or “sleep There are many types of nocturnal myoclonus.” The concern that a neurolo- Nocturnal Events and events that can be mistaken for nocturnal gist might have is that these are Nocturnal Seizures seizures (see Table 1). The history is criti- myoclonic seizures. What distinguishes In some epilepsy syndromes, seizures cal in making the diagnosis. Of course, hypnic jerks from seizures is that they can occur more often either during sleep or the person who is having the event(s) occur at any age, and usually consists of a upon awakening. For instance, frontal may recall little of the event itself. In sudden synchronous extension of two (or lobe onset partial seizures tend to be these instances, the person’s partner or more) limbs, just as the person is falling brief, cluster and occur most often during roommate may provide essential clues. asleep. Sleep myoclonus tends to worsen sleep. The hallmark of idiopathic localiza- What was the description of the event? if there is overuse of stimulants during tion-related epilepsy (often called Benign When during the night did the event the day. Another example is “sleep drunk- Rolandic Epilepsy) is that the centrotem- occur? Was it when the person was going enness,” which can be mistaken for a noc- poral epileptiform discharges increase to sleep? Waking up? Were there complex turnal complex partial seizure (CPS). during sleep. The myoclonic seizures of motor movements, such as automatisms Unlike CPS, which may manifest juvenile myoclonic epilepsy tend to occur like lip smacking, picking or fumbling automatisms, sleep drunkenness consists most often upon awakening. As the name movements of one hand? of stumbling while walking and slurred would suggest, in the syndrome of grand Some events which occur during sleep speech. It occurs in children, just as they mal seizures on awakening, GTCs occur are “normal”—in other words, they do are awakening from a deep sleep. These March 2005 Practical Neurology 77 EPILEPSYESSENTIALS By Steven Karceski, MD automatisms nor tongue biting occur seizures is only just beginning to be Table 1. Differential Diagnosis with night terrors, somnambulism or defined; similarly, little is known about of Nocturnal Events periodic limb movements: these symp- the effect that seizure medications have toms would suggest the diagnosis of on sleep. It is clear that sleepiness is a “Normal” sleep phenomena: seizures. common side effect of many of the • Sleep myoclonus (hypnic jerks) Up to 20 percent of Americans report AEDs. However, some AEDs have been excessive daytime sleepiness at least a few reported to have the opposite effect: fel- • Sleep drunkenness days each week. One percent said that bamate, lamotrigine and zonisamide have they had an automobile accident because been associated with insomnia.2 In other Non-REM Parasomnias: they fell asleep at the wheel. In many of words, the effect that a specific AED will these cases, sleep apnea is the cause of the have in a given individual is unpre- • Sleep terrors daytime sleepiness. Although sleep apnea dictable. More recent studies have sug- • Somnambulism (sleepwalking) is not usually mistaken for seizures, it has gested that certain AEDs like gabapentin been known to cause seizures during may help to increase deep stages of sleep • Somniloquy (sleep talking) sleep. In fact, some people will only and REM sleep. If we tie this information • Periodic limb movements experience a nocturnal seizure due to in with the findings of Dr. Herman, it their apnea. The exact cause of this is seems logical to conclude that one of the unclear, but some have proposed that the mechanisms of action of gabapentin is REM Parasomnias: seizure occur due to prolonged hypoxia. mediated through its direct effect on sleep patterns. However, this is by no • Nightmares (which can sometimes be Sleep, AEDs, and Epilepsy means clear. associated with running, punching or For many centuries, physicians have other complex motor movements) observed that sleep deprivation might Conclusions provoke seizures. In fact, Galen (2nd cen- There is a strong link between seizures events may worsen with sleep deprivation tury AD) and Aristotle (4th century BC) and sleep. First, seizures may occur more or stimulant medications. both noted this association. Recent often during sleep (or shortly after awak- Non-REM parasomnias may also be research by Herman et al. has shown that ening) in certain epilepsy syndromes. mistaken for complex partial seizures. certain stages of sleep suppress seizures.1 These must be distinguished from noc- Night terrors occur in children and Dr. Herman recorded 613 seizures in 133 turnal events which look like seizures. resolve by adolescence. During these, a people with partial epilepsy. She found Second, sleep may have a variable effect sleeping child will suddenly sit up and that seizure rarely occurred during REM on seizures: sleep deprivation may worsen scream. They are usually inconsolable. sleep. In short, the association between seizures, while certain stages of sleep They do not remember the event. sleep and seizures is complex and incom- (REM) may suppress seizures. Third, Somnambulism (sleepwalking) or som- pletely understood. seizures during sleep reduce the quality of niloquy (sleep talking) also occurs in Although lack of sleep provokes sleep. Daytime seizures have a long-last- children, with the incidence peaking at seizures, it has become clear that the ing effect on the brain, and reduce the about 12 years of age. However, it can occurrence of seizures affects the quality quality of sleep the following evening. occur in up to 2.5 percent of adults. of sleep. This observation is not limited Finally, AEDs have a variable effect on Five percent of children and up to 44 to seizures that occur during sleep. In sleep, often causing daytime sleepiness. percent of adults may experience period- other words, seizures that occur during As we learn more about sleep, it’s certain ic limb movements during sleep. What wakefulness will affect the quality of sleep we will clarify the complex relationship distinguishes these movements from that night.2 For instance, seizures decrease between seizure, AEDs, and sleep. PN those which occur in partial or general- total sleep time. In addition, they de- ized seizures is that they preferentially crease the amount of REM sleep, and 1. Herman ST, Walczak TS, Bazil CW. Distribution of Partial Seizures During the Sleep-Wake Cycle: Differences by Seizure involve the legs (less often, they involve prolong the time it takes to reach REM Onset Site. Neurology 2001;56:1453-1459. 2 the arms). Further, periodic limb move- sleep. 2. Vaughn BV, D'Cruz OF. Sleep and epilepsy. Semin Neurol. 2004 ments are not clonic. Finally, neither The relationship between sleep and Sep;24(3):301-13. 78 Practical Neurology March 2005.

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