What happens during a seizure

A seizure is a sudden burst of electrical activity in the brain that causes visible changes in your body or consciousness. During a seizure, neurons fire in an abnormal, synchronized pattern — instead of the usual controlled electrical signals that let your brain communicate with itself, large groups of cells fire all at once. This electrical storm can last from a few seconds to several minutes and can feel very different depending on which part of your brain is affected.

Not all seizures look the same. Some cause you to lose consciousness and shake uncontrollably. Others might cause you to stare blankly for a few seconds, twitch one arm, or feel a strange sensation before anything visible happens. The type of seizure depends on where the abnormal electrical activity starts and how far it spreads through your brain.

Key Takeaways

  • A seizure is a sudden burst of abnormal electrical activity in the brain that can cause shaking, loss of consciousness, staring spells, or other physical changes.
  • Seizures are classified by where they start in the brain — focal seizures begin in one area, while generalized seizures involve both sides from the start.
  • Some seizures cause obvious physical movements, while others cause only internal changes like altered awareness or strange sensations you might be the only one to notice.
  • Seizures can be triggered by sleep deprivation, stress, missed medication, flashing lights, or illness, though many occur without an obvious trigger.
  • What happens after a seizure — confusion, fatigue, or soreness — is called the postictal period and is a normal part of recovery.

Focal seizures: when electrical activity stays in one area

A focal seizure (also called a partial seizure) begins in one specific region of the brain. Because only part of your brain is affected, the symptoms depend entirely on what that area controls. If the seizure starts in the part of your brain that controls your left arm, your left arm might jerk or feel numb. If it starts in the area that processes smell, you might experience a strange odor that no one else can detect.

Focal seizures come in two main types. In a focal seizure without loss of awareness, you stay conscious throughout — you know what is happening, though you may not be able to control your movements or stop the sensation. In a focal seizure with impaired awareness, you lose track of what is going on around you. You might stare, make repetitive movements like lip smacking or picking at your clothes, or wander around. Afterward, you usually will not remember the seizure clearly.

A focal seizure can stay localized or spread to both sides of the brain, becoming what doctors call a focal to bilateral tonic-clonic seizure. This means it starts in one spot but then generalizes — the electrical activity spreads across the whole brain, and you lose consciousness and experience full-body shaking.

Generalized seizures: when both sides of the brain are involved

A generalized seizure involves abnormal electrical activity across both hemispheres of the brain from the very beginning. You lose consciousness immediately, and the seizure affects your whole body. The most recognizable type is the tonic-clonic seizure (formerly called grand mal), which has two phases: the tonic phase, when your muscles stiffen and you may cry out or lose bladder control, followed by the clonic phase, when your whole body shakes rhythmically.

Other generalized seizure types cause different patterns. An absence seizure (formerly called petit mal) is a brief staring spell lasting a few seconds, usually in children — you stop what you are doing, stare blankly, and then resume as if nothing happened, with no memory of the gap. Atonic seizures cause a sudden loss of muscle tone, so you may drop to the ground or your head may nod forward. Myoclonic seizures cause sudden jerking movements, usually of the arms or legs, without loss of consciousness.

What triggers a seizure

Some people with epilepsy have identifiable triggers — specific situations or conditions that make a seizure more likely. Common triggers include sleep deprivation (one of the most frequent), stress, missed doses of anti-seizure medication, illness or fever, hormonal changes related to the menstrual cycle, and alcohol use. Certain people are sensitive to flashing lights or patterns, a condition called photosensitivity.

However, many seizures occur without any clear trigger. You might have a seizure while resting, during normal daily activities, or at random times. This unpredictability is part of what makes epilepsy challenging — you cannot always prevent a seizure even if you know your triggers, and you may never identify what caused a particular seizure.

Keeping a seizure diary can help you spot patterns. Write down when seizures happen, what you were doing beforehand, how much sleep you had, stress levels, and any other details you notice. Over time, patterns may emerge that help you and your doctor understand your individual risk factors.

The postictal period: what happens after a seizure ends

After a seizure stops, your brain does not immediately return to normal. The postictal period is the recovery time that follows, and it can last from minutes to hours depending on the seizure type and severity. During this time, you might feel confused, tired, sore, or have a headache. Some people feel irritable or emotional. Your speech might be slurred, or you might have trouble finding words.

This is a normal part of how your brain recovers from the electrical disruption. You are not having another seizure — your brain is simply resetting. If you have had a tonic-clonic seizure, you may be very sore the next day because your muscles contracted so forcefully. Resting, drinking water, and eating something light can help you recover more comfortably.

How doctors classify and describe seizures

When you see a neurologist, they will ask detailed questions about what happens during your seizures because the pattern of symptoms tells them where in your brain the seizure starts and how it spreads. They may also order an EEG (electroencephalogram), which records your brain's electrical activity and can show the abnormal patterns that occur during a seizure or between seizures.

Doctors use specific terminology to describe seizures precisely. They note whether you lose consciousness, whether movements are present and what kind, whether you remember the event, and how long it lasts. This classification helps them choose the right anti-seizure medication and predict how your epilepsy might progress. Two people with epilepsy can have very different seizure types, which is why treatment is individualized.

Why seizures happen in epilepsy

Epilepsy involves a lasting change in your brain that makes seizures more likely to occur. This might be due to a scar from an old head injury, a brain tumor, a stroke, an infection, a genetic condition, or abnormal brain development. In many cases, doctors cannot find a specific cause even after testing — this is called idiopathic epilepsy.

The underlying problem is usually an imbalance between excitatory signals (which make neurons fire) and inhibitory signals (which calm them down). In epilepsy, the brain is biased toward firing. Anti-seizure medications work by either reducing excitatory activity or increasing inhibitory activity, making seizures less likely. Understanding that seizures are a symptom of an underlying brain condition — not a mental health issue or a character flaw — is important for how you think about and manage your epilepsy.

Frequently Asked Questions

Can you die from a seizure?

Most seizures are not life-threatening. However, a condition called sudden unexpected nocturnal death in epilepsy (SUDEP) is a real but rare risk, occurring in roughly 1 in 1,000 people with epilepsy per year. Status epilepticus — a seizure that lasts longer than 5 minutes or multiple seizures without recovery between them — is a medical emergency. Taking your medication as prescribed and working with your doctor to control seizures reduces these risks significantly.

Will I remember my seizure?

That depends on the seizure type. If you have a focal seizure without loss of awareness, you will remember it clearly. If you lose consciousness — during a generalized seizure or a focal seizure with impaired awareness — you typically will not remember the seizure itself, though you may remember what happened just before it started. Some people have no memory of the postictal period either.

Can seizures cause brain damage?

Single, brief seizures do not cause brain damage. However, prolonged or very frequent seizures may potentially cause harm over time. This is another reason why controlling seizures with medication is important — it reduces the risk of cumulative effects and helps protect your brain health long-term.

What should I do if I see someone having a seizure?

Stay calm, protect them from injury by moving nearby objects away, and place something soft under their head if possible. Do not put anything in their mouth or try to restrain them. Let the seizure run its course. Call emergency services if the seizure lasts longer than 5 minutes, if another seizure starts before they fully recover, or if they do not regain consciousness. Stay with them until they are fully alert.

Can stress or lack of sleep cause epilepsy?

Stress and sleep deprivation can trigger seizures in someone who already has epilepsy, but they do not cause epilepsy itself. Epilepsy is a lasting brain condition that develops due to structural, genetic, or metabolic factors. However, managing stress and maintaining good sleep habits are important parts of seizure control for many people.