The Human Brain and Seizures
The brain is made up of millions of nerve cells called neurons. These cells generate electrical impulses and messages to produce thoughts, feelings, movement and control body functions.
A seizure happens when the normal alternating pattern of these impulses is disrupted, causing the impulses to rapidly fire all at once.
Depending on the type of seizure, this can cause changes in:
- sensation and feeling
- awareness and consciousness
- or movement
Seizures vary greatly and can be very brief or last up to two or three minutes. Most seizures are over in less than two minutes. Some seizures are severe and some very subtle.
Not all seizures are considered epilepsy.
Regions of the brain
The brain is divided into two halves, left and right, called hemispheres. The right hemisphere controls the left side of the body and left hemisphere controls the right. Each hemisphere has four lobes.
The largest structure of the brain is the cerebrum and contains lobes including frontal, parietal, occipital, and temporal lobes. It is the centre of intellect, memory, language and consciousness, receiving and interpreting sensory information and controlling movement.
The frontal lobes are considered our emotional control centre and home to our personality. They are involved in motor function (movement), problem solving, spontaneity, memory, language, initiation, judgement, impulse control, and social and sexual behaviour.
The parietal lobes are involved with touch, temperature and pain perception (sensation), awareness of the body and where it is in space.
The temporal lobes are involved in language, speech, hearing, memory, personality and behaviour.
The occipital lobes are primarily responsible for vision
The brain stem is the stem-like part of the base of the brain that is connected to the spinal cord. It controls the flow of messages between the brain and the rest of the body, and also controls basic body functions such as breathing, swallowing, heart rate, blood pressure, consciousness, and whether one is awake or sleepy.
The cerebellum is responsible for co-ordination, and maintaining of posture, muscle tone, and balance.
If you want to know more about the brain and its functions, go to:
What is a Seizure?
Seizures and epilepsy are not the same. A seizure is an event – a disruption of the normal electrochemical activity of the brain – and epilepsy is a disease of the brain characterised by the tendency to have recurrent seizures.
There are many different types of ‘epilepsies’ and people’s experiences differ greatly.
Under certain circumstances, anyone can have a seizure and not all seizures are diagnosed as epilepsy.
When people have an epilepsy syndrome that is age-dependent and grows past the relevant age, or if someone has been seizure-free for 10 years, with no antiepileptic medication for 5 years, their epilepsy is considered “resolved”.
Seizure Types and Classification
There are many different types of seizures. Here we will discuss some of the more well-known seizure types.
Seizures can be divided into three major groups: focal, generalised and unknown. They are classified as such:
1) Focal Onset Seizures (previously called partial seizures)
About 60% of people with epilepsy have focal onset seizures. Seizure activity starts in one (focal) area of the brain and may spread to other regions of the brain. These seizures can often be subtle or unusual and may go unnoticed or be mistaken for anything from intoxication to daydreaming.
Types of focal onset seizures can be classified by awareness and movement. When the level of awareness is not known, then there is no need to specify it. They are often simply called focal seizures.
Focal seizures can be classified as:
- Focal aware seizures – awareness is retained (formerly called simple partial seizures)
- Focal impaired awareness seizures – awareness is altered during any part of the seizure (formerly called complex partial seizures)
- Focal seizures to a bilateral tonic clonic seizure – this reflects a propagation pattern of a seizure from a focal seizure to a tonic clonic seizure (formerly called secondarily generalised tonic-clonic seizure)
- Focal aware or impaired awareness seizures may further be sorted by any motor-onset or non-motor-onset symptoms
2) Generalised Onset Seizures
Generalised seizures are the result of abnormal activity in both hemispheres of the brain simultaneously. Because of this, consciousness is often lost at the onset of the seizure. Generalised seizures are divided into motor and non-motor (absence) seizures
There are many types of seizures classified as generalised, including:
3) Unknown Onset
This is a grouping of seizures that cannot be diagnosed as either focal or generalised and are thus grouped as unknown. Unknown onset seizures are not truly separate types of seizures, but rather placeholders for seizure types for which the onset is unknown. Sometimes this classification is temporary and as more information becomes available over time or through further testing, the type of seizure may be changed to a generalised or focal onset seizure.
This classification of seizures is when a seizure is unable to be classified due to either:
- inadequate information or
- an unusual nature of the seizure, or
- the inability to classify the seizure as either focal or generalised onset.
Seizures of unknown onset may have features may still be classified as:
- Motor onset
- Non-motor onset or
Most people will only have one or two seizure type(s), which may vary in severity. A person with severe epilepsy or significant damage to the brain may experience a number of different seizure types.
*Certain seizure types can be either of focal, generalised or unknown onset
Classification of a seizure can stop at any level. For instance, “focal onset” or “generalised onset” seizure with no other elaboration is acceptable. This can be extended to descriptors such as “focal sensory seizure,” “focal motor seizure,” “focal tonic seizure,” or “focal emotional seizure,” and so on.
Bilateral versus generalised: Use the term “bilateral” for tonic–clonic seizures that propagate to both hemispheres and “generalised” for seizures that apparently originate simultaneously in both hemispheres
Watch here for the most common types of seizures explained
What the Seizures Look Like
Focal seizures – retains awareness
A person having a focal seizure may not lose consciousness or awareness of what is going on around them. These seizures are known as focal aware seizures. People often refer to these seizures as their “aura”. Focal seizures are classified by whether awareness is retained or impaired (altered). If awareness is unknown, then they are simply classified as a focal seizure.
Focal aware seizures are usually brief, but they can be a warning or ‘aura’ that a more significant seizure may develop. For instance, the seizure may spread to become a focal impaired awareness seizure or evolves into a tonic clonic seizure.
There are too many types of focal aware seizures to describe here. Examples include:
- Focal motor seizures – characterised by movements, such as jerking, posturing or stiffening of arm/s or leg/s, twitching of face
- Focal sensory seizures – characterised by sensations, such as numbness, tingling or burning feeling in a part of the body
- Focal autonomic seizures – characterised by involuntary body changes, such as blushing, looking pale or grey, increased heart rate, nausea, and perspiring.
- Focal cognitive seizures – characterised by impaired language or cognition or features such as déjà vu, hallucinations (visual, smell, taste or hearing), illusions or perceptual distortions.
- Focal emotional seizures – characterised by feeling emotions such as joy, sadness, anxiety, fear or panic.
Focal seizures – impaired awareness
In some types of focal seizures, the person has a change in awareness, consciousness, and behaviour. These are called focal impaired awareness seizures. They can also be called focal seizures.
These focal seizures vary greatly, depending on where they start and spread within the brain and are frequently not recognised as seizures by onlookers. Many of these seizures begin with:
- A vacant stare, loss of expression or a vague, confused appearance.
- Consciousness or awareness is altered and the person may or may not respond.
- If they do respond, it is usually inappropriate.
- Sometimes people have unusual and repetitive behaviour such as chewing, fidgeting, walking around or mumbling.
- The seizure can last from 30 seconds to 3 minutes.
- After the seizure, the person is often confused and may not remember anything that happened just before or during the event.
Typical absence seizure
The most commonly recognised absence seizure is the typical absence seizure. There are other less common types of absence seizures that are briefly discussed here.
A typical absence seizure starts and ends abruptly, is very brief with altered awareness during the seizure. Absence seizures usually begin in childhood (but can occur in adolescents and adults) and are easily missed, or misinterpreted as daydreaming or inattentiveness.
Typically it will look like:
- The seizure starts suddenly with the person stopping their activity
- You will see staring, loss of facial expression and unresponsiveness
- Sometimes eye blinking or upward eye movements are seen
- The seizure can last from two to 20 seconds and ends abruptly
- The person usually recovers immediately and resumes their previous activity, with no memory of what happened during the seizure
These seizures can happen numerous times a day causing learning to be disrupted. They generally respond well to medication.
Absence seizures were previously known as ‘petit mal’ seizures.
The below group are less common absence seizure types:
*Atypical absence seizures
An atypical absence seizure does not start and end as suddenly as a typical absence, it can be more gradual. They are often seen with other features such as loss of muscle tone of the head, trunk or limbs (often seen as a gradual slump) and subtle jerking. These seizures often occur in people with intellectual impairment and complex epilepsies.
The loss of awareness may be minor with the person continuing an activity, but more slowly or with mistakes.
Rhythmic myoclonic jerks of the shoulders and arms and lifting of the arms during the seizure can be seen. The myoclonic jerks are usually seen in both arms, but may be one-sided or not symmetrical. Puckering (jerking) of the lips, twitching of the corners of the mouth, or jaw jerking can also be seen. Sometimes rhythmic jerks of the head and legs may occur. Seizures last 10-60 seconds and typically occur daily.
The level of awareness varies from complete loss of awareness to retained awareness.
*Absence with eyelid myoclonia
These are absence seizures accompanied by brief, often rhythmic, fast myoclonic jerks of the eyelids at the same time with an upward movement of the eyeballs and of the head. This can look like fluttering of the eyelids and simultaneous rolling back of the eyes. These seizures are typically very brief and occur many times a day.
Mostly awareness is retained.
Tonic clonic seizures
A tonic clonic seizure is a seizure that has a tonic (muscle stiffening) and a clonic (muscle jerking) phase, typically in this order, but variations such as clonic-tonic-clonic can also be seen. Tonic clonic seizures are the most recognised seizure type and can be frightening to witness. There are slight variations, but a typical tonic clonic seizure will look like:
- A sudden loss of consciousness, sometimes with vocalisation or calling out
- The eyes, head and body may turn in one direction
- The body becomes stiff (tonic), followed by jerking of the muscles (clonic)
- If standing, the person will fall
- Breathing may be shallow or briefly stopped which may cause the lips and face to look greyish/blue
- The person will not respond when spoken to
- Excess saliva may come of the person’s mouth, and there may also be blood if they have bitten their tongue or the inside of their cheek
- There may be loss of bladder or bowel control so the person may wet or soil themselves
- The seizure usually lasts 2 minutes or less
- It is often followed by a period of confusion, disorientation, agitation, headache, soreness and sleep.
A myoclonic seizure is a seizure where a single or series of single jerks (very brief muscle jerks) occur. They frequently affect the upper body, neck shoulders and arms. A person having a myoclonic seizure usually has sudden jerks on both sides of the body at the same time. They vary in severity but can cause someone to spill or drop what they are holding, or fall off a chair. If severe enough, a myoclonic seizure can also cause a fall.
The seizures are often mistaken for clumsiness before diagnosis.
Even people without epilepsy can experience myoclonus or sudden jerks that may wake you up as you’re just falling asleep. These are normal and not epilepsy.
A tonic seizure involves increased muscle tone of the limbs usually lasting a few seconds, sometimes longer. If the person is standing they will suddenly fall stiffly to the ground. This is often termed a “drop attack” (astatic seizure). Tonic seizures often occur during sleep and in runs of varying intensity of tonic stiffening. The person is unaware during these events. At the beginning of tonic seizures with more intense stiffening, people may make an exhalation or loud sigh sound. With more severe and prolonged tonic seizures the person may look like they have a tremor or shaking, which may be confused with clonic jerking.
Tonic seizures often occur in people with intellectual impairment and more complex epilepsies.
An atonic seizure is a type of seizure that involves the sudden loss of muscle tone. If standing, this can cause a “drop attack” where the person suddenly slumps to the ground. If sitting, a simple head nod (as if the person is trying to fight off sleep) may be seen. These seizures are very brief, less than 2 seconds and may involve the head, body or limbs.
Atonic seizures often occur in people with intellectual impairment and more complex epilepsies.
The below group are less commonly seen:
A clonic seizure is a seizure involving bilateral rhythmic jerking and may occur alone or in combination with tonic (increased muscle tone) activity typically lasting a few seconds up to a minute. The jerking in a clonic seizure is more sustained and rhythmic than seen in a myoclonic seizure.
During a clonic seizure you will see:
- The person’s muscles begin to spasm and jerk
- With a generalised clonic seizure, the elbows, legs, and head will flex, and then relax – rapidly at first, but the rate of the jerks will gradually subside until they stop altogether
- With a focal clonic seizure, the jerking will be isolated to one area of the body
- As the jerking stops, it is common for the person to let out a deep sigh, then normal breathing resumes.
*Myoclonic atonic seizure
A myoclonic-atonic seizure is a myoclonic seizure (sudden jerk) followed by an atonic seizure (sudden loss of muscle tone). Sometimes a series of myoclonic jerks occurs before the loss of muscle tone (atonic). The head and limbs are affected, usually causing a sudden fall. The myoclonic jerk may be subtle.
A negative myoclonic seizure is a generalised seizure with extremely brief stopping of background muscle tone, lasting less than half a second. While this is not enough to cause a person to fall, this causes 1) an initial loss of posture, 2) and a subsequent voluntary, compensatory movement to restore posture. Negative myoclonic seizures may occur in isolation or in a series.
This is a relatively new classification.
For everyday purposes seizures are broadly categorised as either generalised or focal, but there are seizures that cannot be clearly diagnosed as focal or generalised, and may even be considered both. The “Unknown Onset” classification is used when a seizure is unable to be classified due to either:
- not enough information or
- an unusual nature of the seizure, or
- the inability to classify the seizure as either focal or generalised onset.
Unknown onset seizures are not truly separate types of seizures, but rather placeholders for seizure types for which the onset is unknown. Sometimes this classification is temporary and as more information becomes available over time or through further testing, the seizure type may be changed to a generalised or focal onset seizure. For instance a person reports having a tonic clonic seizure, but the onset was not seen. Therefore there is uncertainty if it is a focal to tonic clonic or a generalised tonic clonic seizure.
Epileptic spasms are classified in unknown onset
Epileptic spasms (which include infantile spasms) are seen in infants and appear like:
- A sudden bending or lunging forward (flexion) of the upper body followed by stiffening
- Often the arms are flung out as the knees are pulled up and the body bends forward
- Less often, the head can be thrown back (extension) as the body and legs stiffen in a straight-out position
- Movements can be more subtle and limited to grimacing or head nodding
- These spasms are longer than a myoclonic jerk, but shorter than a tonic seizure.
Each seizure lasts only a second or two but they usually occur in clusters, several in a row.
For more extensive information on seizure types go to:
What is a Syndrome?
There are many different types of epilepsy classifications. Nowadays, most people are given a specific diagnosis or name for their epilepsy, rather than just told that ‘you have epilepsy’. Some epilepsy disorders are classified as syndromes and are defined based on a unique combination of symptoms.
An epilepsy syndrome is a type of epilepsy that depends upon:
- Family history
- What age the seizures start
- Seizure type(s)
- Cause, and other linked diseases/conditions
- How the syndrome progresses over time
- Presence or absence of brain abnormalities
- EEG findings
- Brain scan findings (such as CT, MRI, PET)
- Response to medication
A diagnosis of a particular epilepsy syndrome is useful in deciding the possible treatment options, what course of the condition may take, and the possible genetic risk of passing it on to offspring.
Click Here to read an Epilepsy 360 Magazine Special report: Not Your Everyday Epilepsy
For more information of specific syndromes go to:
For more in-depth and specific syndrome information click here.
What is photosensitive epilepsy?
To some degree, we all find flickering lights or some colours or patterns irritating or difficult to look at, but in some people with epilepsy, seizures are actually triggered by flashing or flickering lights, or by certain geometric shapes or patterns. People who have these seizures are diagnosed with photosensitive epilepsy.
Photosensitive epilepsy is a type of epilepsy we call a reflex epilepsy and is seen in less than 5% of people with epilepsy.
These seizures are more commonly linked with the generalised epilepsies than with focal epilepsies, and because they are usually triggered by visual stimulation, seizures can be reduced by making efforts to avoid the triggers. The person may also have other seizures not triggered by visual stimulation.
Although prognosis is generally very good, photosensitivity and seizures may continue. Medication can help gain seizure control.
How do I know if I am photosensitive?
Some people only have photosensitive seizures, while others may have other seizure types as well as photosensitive seizures. It is important to have a clear diagnosis, and keep good records or a seizure diary to help differentiate the seizures and their triggers.
Photosensitivity can be diagnosed by having a routine EEG with strobe (flickering) light or pattern stimulation.
All routine EEGs should include this.
Today’s lifestyle can involve spending many hours using (visual) technology. While a seizure may occur in these conditions, it may also be a spontaneous or chance event – so don’t conclude your seizures are photosensitive seizures just because you had one or two when using technology.
How is it treated?
In most cases the photosensitive seizures can be well controlled by antiepileptic medication and avoiding known triggers.
What are the triggers? 
Our modern environment is a rich source of potentially seizure-triggering visual stimuli. Typical sources can include:
- strobe, flickering or disco lights
- televisions (TV’s), computers, electronic/videogames
- venetian blinds, striped walls or clothing
- moving escalators
- sunlight reflected off snow, sea or water or interrupted by trees during a ride in a vehicle
Less common stimuli are:
- rotating helicopter blades
- faulty flickering fluorescent lights
- welding lights
New potentially provocative sources turn up now and then unexpectedly.
What are other factors involved?
Whether or not a photosensitive seizure happens is also influenced by:
- whether the eyes are open, closed or closing at the time of the stimulation
- the speed or flicker of the flashing (light)
- the contrast and brightness of the stimuli – in general, with brighter stimuli and strong contrasts in colour, the more likelihood of inducing seizures
- how long the stimulation goes for – a seizure is more likely to occur with longer exposure
- the colour of the flicker (if any) – red flicker is more provocative and colour oscillating from red to blue
- how large and close the screen is – the larger and closer someone is, the more “field of view” it takes up and is more likely to trigger a seizure
Types of stimuli that may trigger a seizure
Avoiding sources of triggers is the best advice. The following precautions only apply to those people who are diagnosed with photosensitive epilepsy.
Television: In Australia most people now use Plasma or LCD TVs. These modern television screens are much less likely to trigger seizures. However, it is important to keep a good distance from the screen. Some seizures may be provoked by the images and colours (especially flashing or alternating) on the screen rather than the screen itself. So the further back a person sits, the less likely a seizure will occur.
Note: Older-style TVs use cathode ray tube (CRT) technology. When you are very close to the screen, you can see the flicker. It is common for people with photosensitivity to be sensitive to this flicker rate, so sit well back from this television type to reduce the risk of seizures. Newer CRT’s now flicker at a much faster rate, almost undetectable by the human eye and outside the most common sensitivity for triggering seizures. Therefore they are much less likely to trigger seizures in people with photosensitivity.
Plasma and Liquid Crystal Display (LCD) TVs do not use the scanning lines of the CRT TVs and therefore don’t flicker. The risk of triggering seizures is not completely removed, but is greatly reduced.
Plasma screens tend to be brighter and have more contrast than LCD screens. Contrasting colours could make seizures more likely for some people with photosensitivity.
If you are choosing between a plasma or LCD television, and you have photosensitive epilepsy, the current advice is to buy an LCD television.
Television images: It is more likely the images are what provokes a seizure, such as flashing sequences or rapid changes from light to dark or to contrasting colours, e.g. from red to blue.
- Sit at least 2.5m from the television screen in a well-lit room
- Sit at an angle rather than directly in front of the screen
- Place a lamp on or behind the television to reduce the contrast between the screen and the surroundings, even when watching during the day
- Use a remote control or place a hand over one eye to lessen the effect of the flicker when manually changing settings
- Do not watch the screen when fast forwarding, rewinding or adjusting the vertical hold
- In the cinema, try to sit well back from the screen and near a light source, eg in an aisle seat where there is a guiding light
- Look away from any content that makes you feel uncomfortable
- A smaller screen set at low brightness and contrast is preferable.
Electronic and video games : Apart from the TV or computer screen itself, the content/images of the electronic or videogames are important; some being more likely to provoke a seizure than others. Other factors may play a role, such as the distance to the screen is shorter in videogame playing than in watching a TV program, and children who play these games for extended periods can suffer visual tiredness, eyestrain and sleep deprivation, which can contribute to seizures.
Usually these games are only likely to trigger seizures if there is an underlying tendency to do so – if it has happened to you before. Generally, a seizure is most likely to occur within the first 30 minutes of play. Prolonged play is not a risk unless associated with sleep deprivation – which is a known trigger for seizures. Television screens used as monitors for video games may also trigger photosensitive seizures.
- Sit as far away from the screen as possible.
- Play the game in a well-lit room and reduce the brightness of the display.
- Avoid continuous exposure to the same pattern and don’t play when overtired.
- Check games for epilepsy or seizure warnings.
- If you do find that a game(s) makes you feel like you are going to have a seizure, then it is best to stop playing and keep exposure to the game in short bursts (have a break every 10-15 minutes) or avoid that particular game altogether.
It is good to take breaks from any electronic games and refresh.
Computer monitors: Computer screen or images on computer screens also have the potential to trigger a seizure. Only in exceptional cases would it be necessary to restrict computer work. If you are sensitive to screen flicker on older monitors, a screen filter may help. You could always try an anti-glare filter to reduce screen glare. High quality monitors, liquid crystal or LCD screens with a flicker (refresh) rate of at least 60Hz may not pose a problem. Once again, it is more likely to be the images on the screen that may cause a seizure.
It is uncommon for seizures to be triggered by hand-held screens.
3D movies:  There is much hype and concern about the effect of 3D movies being a seizure trigger, but this is not the case. In people with photosensitive epilepsy, the risks of a seizure being triggered by 3D movies is no greater than conventional 2D programmes. For people with non-photosensitive epilepsy the risk of 3D movies triggering a seizure is negligible.
Lights: The frequency of a flashing or flickering light most likely to trigger seizures will vary from person to person. Generally it is between 8-30 flashes per second (Hz), but this can vary. Many people seem to be sensitive around 15-20Hz. Again, it is also dependent on the brightness and intensity of the light, and how long the person is exposed to it.
Fans: Ceiling fans in a lit room can create a flicker effect. A pedestal fan is best if you feel the ceiling fan may trigger a seizure.
Geometric patterns: Some people are sensitive to geometric patterns which have strong contrasts of light and dark such as stripes or checks. Some of these patterns can create an optical illusion. Some buildings and public places may have large areas like this, such as carpet. The average person will just feel some visual distortion, but if you feel strange in this environment, it is important to leave or at least cover one eye.
These patterns may also be on a television or computer screen, or something in the natural environment, such as sunlight through trees, or through venetian blinds. Such contrasting patterns are more likely to be a trigger if they are moving, changing direction or flashing, rather than if they are still.
Camera flashes: These rarely trigger seizures unless fired in rapid succession.
Red flickering light and strobe/disco lights: These can trigger seizures, particularly if the room is darkened and there are other triggers such as stress, excitement, tiredness, sleep deprivation and alcohol. For those who are photosensitive, the risk will greatly depend on the speed of the flashing light.
- It is sensible to avoid disco’s if you have photosensitive epilepsy, but this is a common social activity for young people, so it may be a hard one to resist. Some people do attend discos even if they are photosensitive, and find they can tolerate it. Responsible clubs and DJs may display warnings if these lights are used and retail employers may turn off flashing lights in their store if requested.
Sunlight: This can trigger seizures in a number of ways such as: the reflection of light flickering off water or through leaves of trees, and light flickering through posts or railings when moving quickly, e.g. walking past or travelling in a car. Some people may even be affected by looking outside through a screen door.
- Cover one eye with the hand to lessen the effect of the flicker as binocular (looking through both eyes) vision is needed to trigger a seizure.
- Polaroid sunglasses with shaded sides may also help reduce the risk.
Knowing what sources may trigger your photosensitive seizures, and reducing your exposure to them plays the most significant role in reducing or stopping this type of seizure. Some people may need medication, but no specific drug works exclusively or specifically in reflex epilepsy. The choice of drug depends on the type of epilepsy related to the reflex epilepsy.
- Avoid discos.
- Avoid videogames with high contrast flashing.
- Cover or patch one eye if you cannot avoid certain sources of stimulus (eg travelling in a vehicle when sunlight is flickering through the trees).
- Wear glasses that reduce the amount of light as much as possible, such as polarised sunglasses.
- Blue lenses, (type Zeiss Clarlet F133 Z1), have proven effective for many people.
- Use 100-Hz, LCD, or TFT screens.
- Use small TVs and computer screens. Ask about specific computer screens when purchasing a computer.
- Reduce the contrast of TV and computer screens.
- Use a remote control
- Keep a good distance to any screen (ideally at least three times its width).
These are general suggestions, and depending on your sensitivity, not all approaches may be necessary or effective.
For more information go to:
What is photosensitive epilepsy (video 1:34)?
How video games can cause seizures (video 3:14)
Nocturnal Seizures – Seizures during Sleep
Why do so many seizures happen during sleep?
Epilepsy has a complex connection with sleep.
Seizures during sleep can occur with any type of epilepsy. Some people have seizures occurring only during sleep whilst others have both daytime and night-time seizures. People who have only night-time seizures in their sleep are defined as having pure nocturnal epilepsy.
The International League Against Epilepsy (ILAE) defines nocturnal seizures as ‘seizures occurring exclusively or predominantly (more than 90%) from sleep.’
It is estimated around 12 percent of people with epilepsy have nocturnal seizures.
Why do nocturnal seizures occur?
Epileptic seizures are often strongly influenced by the sleep-wake cycle.
When we go off to sleep, we have a change of state – from awake to asleep. But during sleep, there are many changes of state also, which are called sleep stages. It is thought that a change of state has an effect on the brains ‘epileptic activity’ in people with epilepsy. Some seizures occur predominantly at a certain stages of sleep.
It’s believed that nocturnal seizures are triggered by changes in the electrical activity in your brain when moving between the different stages of sleep, and between sleep and awakening stage. As an example, in wakefulness, our brain waves remain fairly constant, but during sleep there are many changes. We go to bed and shift from
- wakefulness to drowsiness to
- light sleep to deep sleep to
- Rapid Eye Movement (REM) sleep
- and this whole cycle occurs 3-4 times per night.
There are dramatic changes on EEG during these sleep stage changes.
Table 1 Stages of Sleep
|Stage 1 – Sleep Onset Non-REM sleep||Stage 2 Non-REM sleep||Stage 3 Non-REM sleep||Stage 4 Non-REM sleep||Stage 5 REM sleep|
|Drowsiness/ very light sleep, easily awoken||Light sleep||Deep sleep starts||Deep sleep||“Active” sleep. When you dream|
|This is when you start falling asleep, and is usually brief.||Your brain activity heart rate and breathing start to slow down. You begin to reach a state of total relaxation in preparation for the deeper sleep to come.||This is also known as slow wave sleep. Your brain waves further slow but there may still be short bursts of faster of brain activity.
If you were to be suddenly awoken during this stage, you would be groggy and confused, and find it difficult to focus at first.
|This is where you experience your deepest sleep of the night. Your brain is mostly slow wave activity, and it’s difficult to wake someone up when they are in this stage||REM sleep means rapid eye movement, which characterises stage 5. Your blood flow, breathing, and brain activity increases, but your muscles go into a paralysis-like state. The brain activity is similar to when you are awake.|
Sleep is divided into 5 stages: Non-REM Stages 1, 2, 3, and 4 and REM sleep.
Seizures don’t seem to happen during REM sleep, but may occur at any other time during the sleep cycle, often in light sleep – that is, stages 1 and 2 of sleep. Nocturnal seizures can also occur when waking or stirring during the night.
This generally means there are more common times at which nocturnal seizures happen:
- Within the first or second hour after going off to sleep (early nocturnal seizures)
- One to two hours before the usual time of wakening (early morning seizures)
- Within the first hour or so after awakening (early morning seizures).
Seizures that occur during sleep may also happen during an daytime nap – they are not limited to night time.
Diagnosing nocturnal seizures
It can be difficult to diagnose nocturnal seizures because they happen during sleep, and the person may not be aware of them happening. Also, nocturnal seizures can be confused with some sleep disorders.
If left undiagnosed, the person may suffer from a lot of daytime sleepiness. This can impact concentration, attention and learning as well as behaviour and emotions resulting in reduced quality of life.
As with most other forms of epilepsy, a good history of the seizures, or even better, an eyewitness account is very important for diagnosis. The doctor may also suggest a video sleep EEG, often done during the day after being sleep deprived.
Are there specific types of epilepsy where people have nocturnal seizures?
Nocturnal seizures can be any type of seizures. Sometimes they are too subtle to detect.
Nocturnal seizures can happen to anyone with epilepsy, but they are often associated with certain types of epilepsy, including:
- Juvenile Myoclonic Epilepsy (JME)
- Awakening Grand Mal (Tonic Clonic)
- Benign Rolandic (also called Benign Focal Epilepsy of Childhood)
- Electrical Status Epilepticus of Sleep (ESES or CSWS)
- Landau-Kleffner Syndrome (LKS)
- Frontal Onset Seizures (such as Nocturnal Frontal Lobe Epilepsy)
Can they change to daytime seizures?
If a person has seizures only during sleep for several years, the chances of the seizures happening during wakefulness is small. However this does not mean daytime seizures won’t occur. For example, in situations of extreme stress or sleep deprivation, medication changes or withdrawal, the risk of a seizure is increased, day or night. Daytime seizures may also occur if someone with nocturnal epilepsy decides to take a nap, or even becomes excessively drowsy during the day.
With good seizure and lifestyle management however, the risks of a daytime seizure can be greatly reduced.
Sleep and seizures – the facts
- One of the most common seizure triggers for many people with epilepsy, is sleep deprivation
- Nocturnal seizures disrupt sleep and increase daytime drowsiness
- Drowsiness can increase the risk of daytime seizures for people affected by seizures during sleep
- Nocturnal seizures are a risk factor for Sudden Unexpected Death in Epilepsy (SUDEP)
- Nocturnal seizures may be misdiagnosed as a sleep disorder and certain sleep disorders may be misdiagnosed as epilepsy
- Some antiepileptic drugs can contribute to sleeping difficulties or daytime drowsiness
- Sleep apnoea is approximately twice as common in people with poorly controlled epilepsy than in the general population
- People with epilepsy with sleep disturbances have a poorer quality of life compared to those with no sleep disturbances. Treatment of the sleep disorder improves seizure control and quality of life
- Lastly, sleep disorders can exacerbate epilepsy and epilepsy can exacerbate certain sleep disorders
How are they managed?
- It is important to aim for the best seizure control possible because nocturnal seizures can interrupt sleep, sometimes quite a lot. This can then become a cycle of sleep deprivation, which is a known trigger for seizures, and consequently more seizures
- Treatment of nocturnal seizures is similar to seizures of a similar nature that occur during the waking hours although sometimes the specialist may recommend a higher evening dose of antiepileptic medication
- Medical management of seizures is based on the type of seizures rather than on the time of occurrence
Practice good sleep habits
Some tips for getting a good night’s sleep include:
- Maintain the same bedtime and rising times as much as possible.
- Work with your internal body clock, so don’t ignore tiredness, go to bed when your body tells you so
- Make sure your bedroom is a restful and calm place to be. Keep it dark at night and open the blinds when you wake up
- Shift work is not recommended as it affects sleep times and quality of sleep
- Some people who have difficulties sleeping, or have interrupted sleep, use sedatives which may ultimately aggravate the problem. Try to improve your sleep regime with more natural techniques
- People with excessive daytime sleepiness often resort to coffee or other forms of stimulants to overcome this, a practice that can also exacerbate seizures, especially if the stimulating substance is used in large amounts. Avoid any caffeinated products or stimulating substances after lunch as this can also affect sleep quality
- Regular exercise can improve a restful sleep. Don’t exercise within four hours of bedtime though
- Keep evening activities calm or use relaxation techniques to establish a more efficient sleep pattern. If there are things you are worried about, don’t think about them just before bedtime
- A regular routine is vital with some people
- If you have tried and failed to improve your sleep, there are many sleep specialists that can help.
For a person with nocturnal seizures, it is suggested:
- Use low bed with padded headboards. Bunks are not recommended
- Avoid large soft pillows, which can increase the risk of smothering. Use instead an anti-smother safety pillow or no pillow at all
- Keep heavy furniture away from the bedside to prevent injury during a fall
- Consider using a safety mats on the floor next to the bed if the person tends to fall out of bed during seizures. Such mats are similar to those used in gyms
- Wall mounted lamps pose less safety risks than ordinary table lamps or study lamps, which can be easily knocked over
- Smoking in bed is unwise for everyone and particularly so for a person with nocturnal seizures.
- Avoid coarse carpets, which can lead to friction burns for those who may fall out of bed. If it’s not feasible to replace carpets, a protective mat or soft rug will suffice
- Finally, people who experience seizures exclusively during sleep and are often able to drive.
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