Seizures can be triggered by a wide range of factors, from missed medication and sleep deprivation to stress, alcohol, hormonal shifts, and metabolic imbalances. For people with epilepsy, missing a dose of seizure medication is the single most common cause of breakthrough seizures. But triggers vary from person to person, and understanding your own pattern is one of the most practical things you can do to reduce your risk.
Missed Medication
Skipping doses of anti-seizure medication tops the list of triggers. Missing one dose is more likely to cause a seizure if you only take your medication once a day, because that single missed dose means a full day without coverage. If you take it two to four times daily, the risk from a single missed dose is lower, but missing several doses in a row significantly raises the chance of a breakthrough seizure.
Sleep Deprivation
Lack of sleep is one of the most reliably reported seizure triggers. When you stay awake longer than normal, the excitability of your brain’s frontal cortex progressively increases. This effect reverses after sleep recovery, which is why a single bad night can raise your risk while getting back on schedule brings it down. Sleep deprivation doesn’t directly cause a seizure the way a specific injury might. Instead, it lowers your seizure threshold, meaning your brain needs less provocation to fire abnormally. This is why neurologists often ask about sleep habits when someone has a new or unexplained seizure.
Stress and Cortisol
Stress is among the most frequently self-reported triggers, and the biology backs it up. When you’re under stress, your body releases cortisol and other glucocorticoids. These hormones increase the firing rate of excitatory brain cells while simultaneously reducing the activity of inhibitory cells, essentially tipping the balance toward overexcitation. In a systematic review of 38 studies, seizures were associated with cortisol increases in 77% of them.
The relationship isn’t always straightforward. Chronic, ongoing stress may have a different effect than a sudden acute stressor. Some people notice seizures not during the peak of stress but in the letdown period afterward. This variability is one reason personal tracking matters.
Alcohol and Withdrawal
Alcohol can trigger seizures in two ways. Drinking heavily lowers the seizure threshold on its own. But for regular heavy drinkers, the more dangerous window comes after stopping. Alcohol withdrawal seizures typically appear 6 to 24 hours after the last drink, with most occurring between 12 and 48 hours after blood alcohol levels drop sharply. About 95% of withdrawal seizures happen within the 7 to 38 hour window. This is a medical emergency, and withdrawal seizures can progress to more dangerous complications if untreated.
Hormonal Changes During the Menstrual Cycle
Some women with epilepsy notice their seizures cluster around specific points in their menstrual cycle, a pattern called catamenial epilepsy. The mechanism comes down to two hormones pulling in opposite directions. Estrogen increases brain excitability by boosting activity at excitatory receptors and suppressing the brain’s main calming chemical (GABA). Progesterone does the opposite, producing metabolites that enhance GABA’s inhibitory effects and quiet neural activity.
Three vulnerable windows exist. The most common is the perimenstrual pattern, when progesterone drops sharply in the days just before and after your period starts. The second is around ovulation (roughly days 10 to 15), when estrogen surges. The third involves cycles where progesterone never rises adequately during the second half, leaving the brain without its usual protective buffer for an extended stretch. If you notice a cyclical pattern to your seizures, tracking them alongside your cycle can help your neurologist adjust your treatment plan.
Metabolic Imbalances
Your brain is extremely sensitive to changes in blood sugar and sodium levels. Low blood sugar (hypoglycemia) can trigger seizures when glucose drops below about 40 mg/dL. This is most relevant for people with diabetes who use insulin, but it can also happen from prolonged fasting or extreme physical exertion without eating. Very high blood sugar, above roughly 290 mg/dL, can also provoke seizures through a different mechanism involving dehydration of brain cells.
Sodium imbalances work similarly. When blood sodium falls below about 115 mEq/L, seizures become likely. If the drop happens rapidly, seizures can occur at even higher sodium levels. Severely elevated sodium, above 160 mEq/L, can also cause neurological symptoms including seizures. These metabolic triggers are why dehydration and skipped meals appear on every list of seizure triggers: both can shift your blood chemistry enough to lower your seizure threshold.
Flashing Lights and Visual Patterns
Photosensitive epilepsy affects about 3% of people with epilepsy. For these individuals, flashing lights between 5 and 30 flashes per second are most likely to trigger a seizure. Common real-world sources include strobe lights, video games, certain TV sequences, and even sunlight flickering through trees while driving. Most people with epilepsy are not photosensitive, so this trigger gets more attention in popular culture than its prevalence warrants. If you’ve never had a seizure in response to flashing lights, it’s unlikely to be a trigger for you.
Illness and Fever
Being sick, particularly with a fever, lowers the seizure threshold in much the same way sleep deprivation does. Fever doesn’t directly cause the abnormal electrical activity behind a seizure, but it creates conditions where seizures happen more easily. This is especially relevant in young children (febrile seizures are common between ages 6 months and 5 years), but adults with epilepsy also report more seizures during illnesses with fever.
Caffeine and Stimulants
Caffeine blocks receptors in the brain that normally have a calming effect, and animal studies suggest it can promote seizures at high doses. In practice, though, the evidence is weak. A study of 174 people hospitalized for seizures found no significant difference in caffeine intake on seizure days compared to seizure-free days. Caffeine does not appear to be a common trigger for most people, though a small number of patients in that study had consumed substantially more caffeine than usual before their seizure. Moderate coffee or tea consumption is unlikely to be a problem, but if you suspect a connection, it’s worth noting in your tracking.
Illicit Drugs
Cocaine, amphetamines, and ecstasy all lower the seizure threshold and can trigger seizures even in people who have never had one before. Synthetic cannabinoids and certain opioids carry similar risks. For people with epilepsy, recreational drug use adds an unpredictable layer of risk on top of their existing vulnerability.
Identifying Your Personal Triggers
Triggers are different for each person, which is why keeping a seizure diary is one of the most useful tools available to you. Record what you were doing before a seizure, how much sleep you got, what you ate and drank, your stress level, where you are in your menstrual cycle if applicable, and whether you missed any medication. Over time, patterns often emerge that aren’t obvious from a single event. Your neurologist can review this information with you and use it to fine-tune both your medication regimen and your daily habits to minimize risk.