EEG (brain wave test) (Electroencephalogram (EEG))

A usually not painful test that records the brain's electrical activity through small sensors on the scalp, used mainly to help investigate seizures and epilepsy.

✓ Medically reviewed by a GMC-registered consultant · last reviewed September 2026 · next review September 2027 · how we review

In short

An EEG records the brain's electrical activity and is used mainly to help investigate seizures and epilepsy.
A normal EEG does not rule out epilepsy, and an abnormal one does not prove it — it is interpreted alongside your symptoms.
The test is usually not painful and uses no needles or radiation; results usually take a few days to a few weeks.
It is a recording of activity, not a scan of the brain's structure — an MRI answers a different question.

A plain-English summary. The detail — including risks and recovery — is below.

At a glance

TypeDiagnostic test (neurophysiology)

AnaestheticNot needed

How long it takesRoutine recording about 20–40 minutes; the visit takes around an hour

Hospital stayOutpatient — usually no hospital stay (some types are done over days)

Time off workUsually none after a routine EEG

When you'll see resultsUsually a few days to a few weeks, after a specialist reviews the recording

On the NHS?Widely available on the NHS when clinically indicated; private access is often used for speed

A general guide. Your specialist will give you advice for your situation.

Best fit

Helps support or question a diagnosis of epilepsy and identify the seizure type

Pause if

An EEG is not a test of brain structure — if a tumour, stroke or other structural cause is the concern, an MRI or CT scan is the right test.

Main recovery point

You rest while activity is recorded, with short tasks such as eye opening, deep breathing and looking at a flashing light.

Good aftercare

A specialist-reported result interpreted alongside your symptoms by a neurologist.

During the test

You rest while activity is recorded, with short tasks such as eye opening, deep breathing and looking at a...

Straight after

The sensors are removed and your scalp wiped. Your hair will feel sticky until washed. You can usually drive and...

Same day

Wash your hair at home to remove the paste fully. There are no lasting after-effects from a routine EEG.

A few days to a few weeks

A specialist reviews the recording in detail and sends a report to the doctor who requested it.

Medical line illustration of EEG scalp electrodes and brainwave recording for EEG (brain wave test). — Illustration only - not a diagnosis, medical advice or a promise of result. Your anatomy and treatment plan may differ. Vuemedics does not publish before-and-after photos.

What is an EEG (electroencephalogram)?

An EEG (electroencephalogram) is a test that records the tiny electrical signals your brain produces. Small sensors called electrodes are placed on your scalp and connected to a recording machine, which captures your brain's activity as wavy lines.

Its main use is to help investigate seizures and epilepsy — for example, to look for unusual electrical patterns and to help work out what type of seizures someone has. It is also used in some sleep disorders and conditions such as encephalitis (inflammation of the brain).

An EEG shows brain activity during the recording; it is not a picture of the brain's structure. For that, a scan such as an MRI is used. The two tests answer different questions and are often used together.

Importantly, a normal EEG does not rule out epilepsy, and a slightly unusual EEG does not by itself prove it. The result is one piece of information that a neurologist puts together with your symptoms and any witness accounts.

Types, options & approaches

There may be different ways to do this. The right approach depends on the clinical question and your circumstances.

Routine (standard) EEG

Done in a hospital department while you rest. The recording usually lasts about 20–40 minutes, with the whole visit taking around an hour.

Sleep-deprived EEG

You stay awake the night before, as tiredness can make certain abnormal patterns easier to detect. You will usually need someone to bring you home.

Sleep EEG

Recorded while you sleep, sometimes with the help of medication, because some patterns appear mainly during sleep.

Ambulatory EEG

You wear a small portable recorder and go about normal daily life, usually for 24 hours or more, so activity is captured over a longer period.

Video telemetry EEG

An EEG recorded with video over several days in hospital, to capture and study episodes as they happen and link symptoms to the brain activity at that moment.

EEG compared with an MRI brain scan

	EEG	MRI brain scan
What it shows	Brain electrical activity over time	Detailed pictures of brain structure
Main use	Seizures, epilepsy, some sleep and brain-inflammation problems	Tumours, strokes, MS, structural causes
Sensation	Usually not painful; sensors on the scalp	Usually not painful; noisy, enclosed scanner
A normal result means	No abnormal activity seen during the recording	No structural problem seen on the scan

These tests answer different questions and are often used together rather than as alternatives.

Preparing for your test

Wash your hair the day before or on the day, and do not use any gel, wax, oil, mousse or hairspray, as products stop the sensors sticking.
Remove weaves, braids, hair extensions or wigs beforehand if you wear them.
Eat and drink normally unless you are told otherwise; not skipping meals helps avoid low blood sugar affecting the recording.
Take your usual medicines as normal unless your neurologist specifically tells you to change them — do not stop epilepsy medicines on your own.
Tell the department if you are sensitive to flashing lights, as part of the test may involve looking at a flashing light.
For a sleep-deprived EEG, follow the staying-awake instructions and arrange a lift home.
Bring something to tidy your hair afterwards, as the sensors leave a sticky paste.

What happens

A clinical physiologist measures your head and marks where the sensors go. They then attach small electrodes to your scalp with a sticky paste (and sometimes a soft cap). This part takes a little while but does not hurt.

During the recording you usually sit or lie still with your eyes closed, opening and closing them when asked. You may be asked to breathe deeply (overbreathe) for a few minutes, and to look at a flashing light (called photic stimulation). These activation methods are used because they can bring out abnormal patterns that help with diagnosis. Tell the staff at once if you feel unwell during them.

After the recording, the electrodes are removed and your scalp is wiped, though your hair will feel sticky until you wash the paste out at home. You can normally return to your usual activities straight away. The recording is then reviewed in detail by a specialist before a report is sent to the doctor who arranged the test.

Is this test right for me?

A good consultation should explore whether it's the right choice for you now — including reasons to wait or consider something else.

May not be suitable if…

An EEG is not a test of brain structure — if a tumour, stroke or other structural cause is the concern, an MRI or CT scan is the right test.
A single routine EEG is a poor way to capture infrequent episodes; a longer recording (ambulatory or video telemetry) may be needed instead.
Routine EEG is not a useful 'screen' in people without relevant symptoms, as minor variations can be over-interpreted.
It cannot, on its own, confirm or exclude epilepsy.

Delay or rearrange if…

You have hair products, weaves, braids or wigs in place that would stop the sensors sticking — these need removing first.
You are acutely unwell with fever, confusion or a stiff neck, which needs urgent assessment rather than a routine test.
Your neurologist has asked for a specific medicine change before the test that has not yet been done safely.
You cannot arrange a lift home and a sleep-deprived EEG has been requested.

Alternatives to discuss

A careful clinical history and witness account, which often contribute more to a seizure diagnosis than the EEG.
An MRI or CT scan when a structural cause needs to be looked for.
A longer or repeat EEG, or video telemetry, if a routine test does not capture the problem.
Heart tests (such as an ECG) where blackouts might have a cardiac rather than neurological cause.
No test, with monitoring and a clear safety net, if symptoms are mild and uncertain.

Before you decide

Use this as a shared-decision checklist. The aim is not just “can this be done?”, but whether it is right for you, now, with the risks and alternatives clearly understood.

What matters most to me?

Think about symptoms, daily life, work, caring responsibilities, sport, fertility, travel, appearance and anxiety — the right choice depends on your priorities, not just the medical facts.

What are all my options?

Ask about waiting, monitoring, medicines, rehabilitation, a smaller or larger procedure, a different test, NHS referral, or a second opinion where that would help.

What would make me pause?

Active infection, pregnancy, unstable medical problems, smoking, medicines that increase bleeding, poor support at home, or feeling pressured are all reasons to slow down and get tailored advice.

What happens if I do nothing today?

For some problems, waiting is safe; for others, delay can make treatment harder. A good consultation should explain the trade-off in plain English.

Benefits

Helps support or question a diagnosis of epilepsy and identify the seizure type
Can guide which epilepsy treatment is most suitable
May help distinguish epileptic seizures from other kinds of episodes
Useful in some sleep disorders and in suspected brain inflammation
Usually not painful, needle-free and uses no radiation

Risks & complications

More common

Sticky paste left in the hair until you wash it out
Mild discomfort from sitting still or from the deep-breathing part
A normal result even when a problem exists, because activity may be normal during the recording
Needing a different or repeat type of EEG to capture more information

Less common

Temporary light-headedness or tingling from the deep-breathing (overbreathing) part
Mild skin irritation where the electrodes were attached
Finding the flashing-light part briefly unpleasant

Rare but serious

A seizure during the test, sometimes brought on deliberately by the activation methods so it can be recorded under controlled conditions

The EEG itself is very low risk. The bigger issues are interpretation: a normal recording does not rule out epilepsy, and minor variations can be over-read. Tell the staff if you are known to be sensitive to flashing lights. Do not stop or change epilepsy medicines for the test unless your neurologist has specifically told you to.

Published figures to discuss

The EEG is a recording, so procedural complications are minimal. The meaningful numbers are about accuracy. A single routine EEG detects abnormal activity in only a proportion of people who do have epilepsy, so a normal result is common and does not exclude the condition; repeating the test or recording for longer increases the chance of capturing an abnormality. Because reported detection rates vary widely with the technique, timing and condition, exact percentages are not given here.

Figure	Reported range	How to interpret it	Source / confidence
Normal EEG despite epilepsy	Common	A routine EEG records a short window; normal results do not rule out epilepsy.	Guide sourcesClinical context
Incidental epileptiform activity	Recognised	An abnormal EEG without matching clinical seizures can mislead; results must fit the history.	Guide sourcesClinical context
Provoked seizure during EEG	Uncommon but expected possibility in some protocols	Flashing lights, sleep deprivation or hyperventilation can provoke abnormalities; staff should explain safety steps.	Guide sourcesClinical context
Skin irritation from electrodes	Minor and temporary	The EEG records brain waves; it does not put electricity into the brain.	Guide sourcesClinical context

These are literature figures, not a personalised prediction. Your own risks and likely benefits depend on your circumstances, your health, and how your care is carried out and followed up.

What happens afterwards

There is no physical recovery from a routine EEG. 'Afterwards' is mainly washing the paste out of your hair, getting back to normal activities, and waiting for the specialist report.

During the test

You rest while activity is recorded, with short tasks such as eye opening, deep breathing and looking at a flashing light.

Straight after

The sensors are removed and your scalp wiped. Your hair will feel sticky until washed. You can usually drive and return to normal activities (a sleep-deprived EEG is the main exception).

Same day

Wash your hair at home to remove the paste fully. There are no lasting after-effects from a routine EEG.

A few days to a few weeks

A specialist reviews the recording in detail and sends a report to the doctor who requested it.

Follow-up

Your neurologist explains what the result means alongside your symptoms, and what should happen next.

What's normal — and not a worry

Sticky, slightly messy hair until you wash the paste out
Feeling a little tired, especially after a sleep-deprived or overnight recording
Mild, brief tingling or light-headedness if you did the deep-breathing part
Waiting a while for the report before anything is confirmed

Aftercare

Wash your hair to remove all the paste; a second wash is often needed.
Return to your usual activities, including work, unless you were told otherwise.
Do not drive after a sleep-deprived EEG until you are properly rested — arrange a lift.
Keep taking your medicines as normal unless your neurologist advised a specific change.
Keep a diary of any seizures or episodes, especially during an ambulatory or telemetry recording.
Make sure you know who will give you the result, and roughly when.
Contact your clinician if your symptoms change while you wait for the report.

Before your test

Hair washed (no gel, wax or oil on the day)
Lift home arranged if it is a sleep-deprived EEG
Usual medicines continued unless told otherwise
Flashing-light sensitivity flagged to staff beforehand
Seizure or symptom diary ready (for longer recordings)
Clear note of who reports the result and when

⚠ Get urgent help if…

A seizure lasting more than five minutes, or one seizure straight after another without recovery — call 999
A first-ever seizure, or a seizure with a head injury, breathing difficulty or that happened in water
Confusion, weakness or difficulty speaking that does not quickly settle after an episode
Severe or persistent headache, fever or a stiff neck
Any symptom your neurologist specifically told you to treat as an emergency
Skin at the electrode sites becoming red, painful, swollen or weeping over the following days

Who to contact: your clinician, clinic or test provider first (keep their number to hand). For urgent advice when you can't reach them, call NHS 111. In an emergency, call 999.

General guidance — it doesn't replace the specific advice your specialist gives you.

Results & realistic expectations

A 'normal' EEG means no abnormal electrical activity was seen during that particular recording. Because many people with epilepsy have a normal routine EEG between seizures, this does not rule epilepsy out. An 'abnormal' EEG can support a diagnosis and help identify the seizure type, but minor changes can occur in people without epilepsy too.

For this reason the EEG is never read in isolation. A neurologist interprets it together with your symptoms, any witness accounts and other tests. The result helps build the overall picture rather than giving a single yes-or-no answer.

How long it lasts

An EEG captures a moment in time. If your symptoms change, or the first recording did not capture an episode, a repeat EEG or a longer type (such as ambulatory or video telemetry) may be suggested later. A normal EEG from the past does not guarantee a normal recording now.

Related tests, treatments or support

An EEG is often combined with other investigations, particularly an MRI brain scan to look at the brain's structure, and blood tests. In suspected epilepsy, the EEG, the scan and a careful account of the episodes are usually considered together.

Follow-up & long-term care

The recording is reviewed by a specialist and a report is sent to the doctor who requested it, usually within a few days to a few weeks. You will normally discuss the result with your neurologist, who will explain what it means for you and whether any further tests or treatment are needed.

Repeat, follow-on and what comes next

A normal first EEG is common in epilepsy and frequently leads to a repeat or a longer recording.
Capturing an actual episode (for example with video telemetry) is sometimes needed to be sure.
Borderline findings may need expert review or a second opinion to avoid over-diagnosis.

Ask what happens if the result is unclear or needs repeating, and what is included if further tests or follow-up are needed.

What good aftercare looks like

A specialist-reported result interpreted alongside your symptoms by a neurologist.
A clear plan for whether a repeat or longer recording is needed.
A named contact and safety-net advice about seizures while you wait for results.
A defined process for how and when you will be told the result.
Sensible, specialist-led advice on medicines and driving rather than ad hoc changes.

What affects the cost

Costs vary a great deal between people and providers, and we don't publish prices. What matters is understanding what drives the cost and making sure your quote is complete. The main things that affect it:

The type of EEG — a routine recording costs less than ambulatory or multi-day video telemetry
The length of the recording and whether video is included
The specialist time needed to review and report the recording
Whether sleep deprivation or sleep recording is involved
Any follow-up appointment to discuss the result
Whether other tests, such as an MRI, are done at the same time (charged separately)

Make sure your written quote includes

The fee for the EEG itself and which type it covers
Whether specialist reporting is included in the price
The cost of a follow-up to discuss the result
What a repeat or longer recording would cost if the first is inconclusive
Whether any other tests are needed and how they are charged
Cancellation and rebooking policy
How and when you will receive the report

On the NHS? EEGs are widely available on the NHS when there is a clinical reason, such as investigating seizures; private testing may be used for a shorter wait, but the test itself is the same.

You're entitled to your total cost in writing — including reports, follow-up and what happens if the result is inconclusive — before you decide.

Choosing a specialist safely

Check the specialist is on the GMC Specialist Register for this area.
Make sure they work at a CQC-registered service, and look for membership of the relevant Royal College or professional body.
You're entitled to time to consider and to have your questions answered before you agree — the specialist who looks after you should explain it, not a salesperson.
Be wary of pressure: time-limited offers or deposits taken before you've had time to think are red flags, not bargains.
You're entitled to your total cost in writing — including any follow-up — before you decide.

How Vuemedics verifies every consultant →

Questions to ask your medical professional

Take this to your consultation. A good specialist will welcome every one of these.

What are you hoping this EEG will show or rule out?
If it is normal, does that change anything, and would I need a repeat or a different type?
Should I take my usual medicines as normal before the test?
Which type of EEG is best for my symptoms — routine, sleep-deprived, ambulatory or video telemetry?
Who will explain the result to me, and when?
Are you on the GMC Specialist Register for this area, and which Royal College or professional body are you a member of?
Will you be the specialist who carries out my test, and who looks after me afterwards?
What are the risks for someone like me, and how often do your own patients have a problem or need it repeated or redone?
What does a realistic result look like — and what can this test not achieve?
What are my options, including waiting, doing nothing for now, or choosing a different approach?
Can I have written information, results and aftercare instructions in a format I can use, including any accessibility or communication support I need?
What is the total cost in writing, including any follow-ups, and how much time do I have to decide?

Frequently asked questions

Is an EEG painful?

No. The sensors sit on the surface of your scalp and held on with paste. There are no needles and no electric shocks — the machine only listens to your brain's own activity. The deep-breathing part can feel a little odd but is not painful.

Can an EEG diagnose epilepsy on its own?

No. A normal EEG does not rule out epilepsy, and a mildly abnormal one does not prove it. The test is interpreted alongside your symptoms, witness accounts and other tests by a neurologist.

Will the flashing lights cause a seizure?

Only a small number of people are sensitive to flashing lights. The light part (photic stimulation) is done carefully and stopped at the first sign of a problem. Tell the staff beforehand if you know you are sensitive to flashing lights.

Can I take my medicines before an EEG?

Usually yes — take them as normal, and do not stop epilepsy medicines on your own. Only change anything if your neurologist has specifically told you to for the test.

How long until I get the results?

Usually a few days to a few weeks. The recording has to be reviewed in detail by a specialist before a report is sent to the doctor who arranged it.

Can I drive and go to work afterwards?

After a routine EEG, usually yes, straight away. The main exception is a sleep-deprived EEG, after which you should not drive until properly rested, so arrange a lift home.

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How we made this page

Medically reviewed by a GMC-registered consultant. Written in plain English, checked against NHS, NICE, GMC and relevant Royal College / specialist-society guidance, and kept under review. No clinic paid to appear on this page, and we publish no pricing. This is general information to help you prepare — it is not a substitute for advice from your own clinician. How we review our guides →

Source hierarchy: UK regulator and NHS/NICE guidance first, then relevant Royal College or specialist-society guidance, then peer-reviewed evidence for procedure-specific figures where available.

Sources & standards: NHS — Electroencephalogram (EEG) NHS — Electroencephalogram (EEG) conditions page Brain & Spine Foundation — Getting a diagnosis (tests) Epilepsy Action — EEG tests for epilepsy NICE — Epilepsies in children, young people and adults (NG217)

Reviews reflect patients' experience of care, not clinical outcomes. For procedure volumes and outcome data see PHIN.

Last medically reviewed 2026-09-21. Spotted something wrong or out of date? Report an error in this guide.