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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