Quick answer: An EEG (electroencephalogram) is a painless, completely safe test that records the electrical activity of your brain using small sensors placed on the scalp. In Singapore it is most often used to help diagnose and characterise epilepsy and seizures, and to investigate blackouts and other unusual episodes. It does not give any electric shock — it only listens to your brain’s natural “brain waves”. It is usually arranged by a neurologist, or at KKH or NUH for children.
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If your doctor has suggested an EEG, it is natural to feel a little uncertain about what the test involves. The good news is that an EEG is one of the gentlest tests in medicine: nothing is injected, nothing is put inside you, and you feel no pain. This guide explains what an EEG is, why it is done, how to prepare, and what to expect on the day, in plain language and with a Singapore context.
What an EEG is
An EEG is a painless test that records the electrical activity of the brain. Your brain cells communicate using tiny electrical signals, and an EEG picks these up through small sensors called electrodes that are placed on the scalp. The signals are displayed as wavy lines — often called “brain waves” — which a specialist reviews. By studying the pattern, rhythm and timing of these waves, doctors can spot unusual activity that may not show up on other tests, and build a clearer picture of how your brain is working.
Why an EEG is done
The most common reason for an EEG is to help diagnose and characterise epilepsy and seizures. It can show patterns that support a diagnosis and help the neurologist understand what type of seizures you may be having, which guides treatment. An EEG is also used to investigate blackouts and other unusual episodes, to help assess conditions such as encephalitis (inflammation of the brain), and to look into certain other brain and sleep problems. In some situations it is used simply to assess the overall level of brain activity.
Types of EEG in plain terms
There are a few common forms of the test. A routine EEG is the standard recording, usually done while you rest quietly for a short session. A sleep-deprived EEG is done after you have deliberately slept less than usual, because tiredness can make certain patterns easier to detect. Video-EEG monitoring records your brain activity alongside a video of you over a longer period; this is useful for capturing episodes as they happen, so the team can see exactly what your brain is doing during an event.
How to prepare
Come with clean, dry hair. Wash it beforehand and avoid oils, gels, sprays or other hair products, as these stop the electrodes from sticking well. Ask the clinic about sleep instructions — for some EEGs you may be asked to sleep less the night before. Also check which of your regular medicines you should continue or pause; usually you carry on as normal, but always follow the specific advice given to you. It can help to bring a list of your medicines and a description of the episodes being investigated.
What happens during the test
A technician gently attaches the electrodes to your scalp using a special paste. You then relax, usually lying down or sitting comfortably with your eyes closed for parts of the recording. You may be asked to breathe deeply for a short while, or to look at a flashing light, because these can bring out certain brain-wave patterns that help with diagnosis. The whole test is painless and does not give any electric shock — the electrodes only record signals coming from your brain; they do not send anything into it.
After the test
Once the recording is finished, the electrodes are removed and the paste is washed out of your hair. It is harmless but can feel a little sticky, so you may wish to bring a comb or wash your hair again at home. You can return to your normal activities straight away. If you had a sleep-deprived EEG and feel drowsy, it is sensible to arrange for someone to accompany you or to avoid driving until you feel fully alert.
What an EEG can and cannot show
An EEG is a valuable piece of the puzzle, but it is not a stand-alone answer. It supports a diagnosis rather than proving one on its own. Importantly, a normal EEG does not rule out epilepsy — the unusual activity may simply not have appeared during the recording. Likewise, an abnormal EEG is always interpreted alongside your symptoms, your history and any other tests. Your neurologist puts the whole clinical picture together before reaching a conclusion.
Is it safe?
Yes. An EEG is completely safe and painless, which is one of the most reassuring things about it. It simply listens to your brain and does not pass any current into you. The flashing-light part of the test is done carefully and under supervision; if you have any concerns about flashing lights, tell the technician beforehand so they can take extra care. There is no lasting effect and you can go about your day normally afterwards.
When to see a doctor
An EEG is usually part of an assessment already arranged by your doctor, so keep your follow-up appointment to discuss the results. See a doctor if you have new or recurring blackouts, unusual episodes or suspected seizures that have not yet been assessed. Seek urgent help — call 995 — if a seizure causes injury, lasts a long time, or if seizures happen one after another without the person recovering in between, as these are emergencies. When in doubt about a suspected first seizure, get it reviewed promptly.
Common questions
Does it hurt or give a shock?
No. An EEG does not hurt and does not give any electric shock. The electrodes only record your brain’s own signals; nothing is sent into your body.
Will I need to have my head shaved?
No. The electrodes sit on the surface of the scalp between the hair. You only need to arrive with clean, product-free hair.
How long does an EEG take?
A routine EEG is a fairly short session, while sleep-deprived and video-EEG recordings take longer. The clinic will tell you what to expect for your particular test.
Can my child have an EEG?
Yes. Children can have EEGs safely, and in Singapore these are commonly arranged through paediatric services such as KKH or NUH. Staff are experienced at keeping children calm and comfortable.
Should I keep taking my usual medicines?
Usually yes, but always follow the specific advice from your clinic, as some tests have particular instructions. Bring a list of your medicines with you.
Related guides
Sources
- National Neuroscience Institute
- HealthHub
- NHS
- Epilepsy Foundation
Disclaimer: This guide is for general information only and does not replace professional medical advice. It should not be used to diagnose or treat any condition. Please consult a qualified doctor or a neurologist about your own situation. In an emergency, call 995.