Seizures in epilepsy are triggered when something tips the brain’s balance between excitation and inhibition, causing neurons to fire uncontrollably. The most common triggers are sleep deprivation, stress, missed medication, alcohol, flashing lights, hormonal changes, illness, dehydration, and skipped meals. But triggers are highly individual, and understanding yours is one of the most practical things you can do to reduce seizure frequency.
How Triggers Actually Work in the Brain
Your brain constantly maintains a balance between signals that excite neurons and signals that calm them down. Everyone has what researchers call a “seizure threshold,” which is the level of inhibition that must be overcome before neurons start firing out of control. Genetics, past brain injuries, and prior seizures all influence where that threshold sits for you. Triggers don’t cause epilepsy. They temporarily lower your threshold, making a seizure more likely on a given day.
Even a brain with high natural resistance to seizures can be pushed past its threshold by severe metabolic disruption or acute injury. For people with epilepsy, the threshold is already closer to that tipping point, so everyday factors like poor sleep or a skipped meal can be enough to cross it.
Sleep Deprivation
Sleep deprivation is one of the most powerful seizure activators across nearly all types of epilepsy. Research published in Neurology found that after 20 or more hours of continuous wakefulness, people with epilepsy showed measurably increased cortical excitability. The likely mechanism is reduced activity in the brain’s inhibitory circuits, essentially weakening the brakes that normally prevent neurons from firing in unison.
This isn’t limited to pulling an all-nighter. Fragmented sleep, inconsistent sleep schedules, and chronic under-sleeping all contribute. If you notice seizures clustering after late nights or disrupted rest, sleep is almost certainly playing a role.
Stress and Cortisol
Stress is one of the most frequently reported triggers, and the biology backs it up. A systematic review of 38 studies found that seizures were associated with elevated cortisol levels in 77% of cases. Stress hormones increase excitability in the hippocampus, a brain region deeply involved in temporal lobe epilepsy, by boosting excitatory signals while simultaneously suppressing inhibitory ones.
The relationship isn’t always straightforward. Chronic stress may gradually shift your brain’s baseline excitability, while acute stress, like a sudden argument or a panic-inducing situation, can provoke a seizure more immediately. Emotional stress and physical stress (fever, pain, exhaustion) both count.
Missed Medication
Skipping a dose of anti-seizure medication is a common and avoidable trigger. Missing one dose doesn’t guarantee a seizure, but it raises the risk, especially if you take your medication only once a day. In that case, a single missed dose means a full day without protection. If you take medication two to four times daily, the impact of one missed dose is smaller because the gap in coverage is shorter.
Setting phone alarms, using pill organizers, and keeping a backup dose in your bag are simple strategies that make a real difference. If you do miss a dose, take it as soon as you remember rather than waiting for the next scheduled time, and let your care team know if it becomes a pattern.
Alcohol and Substance Use
Alcohol lowers the seizure threshold while you’re drinking, but the bigger risk comes during withdrawal. Seizures typically occur within 12 to 24 hours after the last drink in people who drink heavily and then stop abruptly. These are major motor seizures that can happen even in people who have never had a seizure outside of withdrawal.
For people with epilepsy, even moderate drinking carries risk. Alcohol also interferes with how anti-seizure medications are absorbed and metabolized, which can make your usual dose less effective. Illicit drugs, particularly stimulants, carry their own seizure risks.
Hormonal Changes and Menstrual Cycles
Some women with epilepsy experience a predictable increase in seizure frequency during specific phases of their menstrual cycle, a pattern called catamenial epilepsy. Seizures most commonly cluster around menstruation, when progesterone levels drop. Progesterone has a calming effect on the brain through one of its byproducts, which enhances the brain’s main inhibitory signaling system. When progesterone falls, that protective effect diminishes.
Tracking seizures alongside your cycle on a monthly calendar can help you and your doctor identify whether this pattern applies to you. If it does, treatment adjustments timed to your cycle may help.
Flashing Lights and Screens
Photosensitive epilepsy affects a subset of people with epilepsy, not everyone. Flashing lights between 5 and 30 flashes per second are most likely to trigger seizures. Safety guidelines recommend that people with photosensitivity avoid exposure to flashes faster than three per second.
Common sources include strobe lights, flickering fluorescent bulbs, sunlight flashing through trees while driving, and certain video content. Video games and virtual reality headsets have long carried seizure warnings, though a 2025 systematic review of nearly 900 patients across more than 1,800 VR sessions found no seizures when appropriate visual content was used. A history of photosensitivity doesn’t mean you must avoid all screens, but you should avoid content with rapid strobing or high-contrast flickering patterns.
Blood Sugar and Electrolyte Shifts
Your brain depends on a steady supply of glucose and a narrow range of electrolyte levels. When those go significantly off balance, seizures can follow.
- Low blood sugar: Seizures typically occur when glucose drops below 40 mg/dL, a level associated with severe hypoglycemia. This is most relevant for people with diabetes who use insulin, but can also happen after prolonged fasting or extreme physical exertion without eating.
- Sodium: Seizures from low sodium generally occur below 115 mEq/L, though a rapid drop can trigger them at higher levels. Extremely high sodium (above 160 mEq/L) also causes neurological problems.
- Calcium: Low calcium levels between 5 and 6 mg/dL can provoke seizures, as can severe elevations above 13.5 mEq/L.
For most people, these extremes won’t happen through normal daily life. But dehydration, prolonged vomiting or diarrhea, extreme dieting, and certain medications can push electrolytes into dangerous territory. Staying hydrated and eating regular meals is a simple way to keep these levels stable.
Illness and Fever
Being sick, particularly with infections that cause fever, is a well-recognized seizure trigger. Fever itself raises brain excitability, and the immune system’s inflammatory response can further disrupt the excitation-inhibition balance. Childhood fevers are a specific risk factor that can alter brain receptor function in ways that increase seizure susceptibility later in life.
Intercurrent infections, meaning any illness you develop while living with epilepsy, are considered one of the key transient factors that shift individual seizure susceptibility day to day.
Weather and Seasonal Patterns
Some people notice seizures are more frequent in certain seasons, and there is evidence to support this. Research has found a statistically significant increase in seizure frequency during winter, associated with lower temperatures, higher humidity, higher atmospheric pressure, and reduced daylight hours. Days with shorter sunlight exposure (around 10.8 hours versus 12.7 hours) were linked to more seizure activity.
Atmospheric pressure changes alone don’t appear to be a reliable trigger in controlled studies. The seasonal effect may have more to do with reduced sunlight, lower vitamin D levels, changes in sleep patterns during darker months, or the increased likelihood of illness in winter.
Tracking Your Personal Triggers
Triggers vary enormously from person to person. What provokes a seizure in one person may have no effect on another. The most effective way to identify your specific triggers is to keep a seizure diary, recording not just when seizures happen but what preceded them: how much you slept, what you ate, your stress level, whether you missed medication, where you are in your menstrual cycle, and any illness or unusual activity.
You can use a paper calendar for a simple visual overview, or use a phone app or digital log for more detail. The Epilepsy Foundation recommends sitting down with your care team to decide which details are most useful to track for your situation. Over weeks and months, patterns often emerge that aren’t obvious in the moment. That information becomes one of your most valuable tools for reducing seizure frequency alongside medication.