Preparing for a sleep-deprived EEG for epilepsy: who decides the plan, what to record and what to bring

Your neurologist has suggested a sleep-deprived EEG, a brain recording after a night with less sleep. Preparation means following your clinic's instruction for the night. It also means knowing what to ask and bringing past results with a description of your seizures. You can note the weeks before on paper, or in the seizure diary in Sam once a doctor has confirmed epilepsy. There, Apple Health sleep, heart rate variability and resting heart rate sit a few taps from an entry you make today. Only your doctor decides the plan for the night.

This text is general information, not medical advice. Only your clinic decides how your night before the test looks, and you do not change your medicine on your own.

What is a sleep-deprived EEG for?

An EEG records the tiny electrical signals your brain produces. Electrodes on your scalp pick them up and show them as wavy lines on a screen. The NHS says the main condition an EEG is used for is epilepsy.

A sleep-deprived EEG is done after less sleep than usual. When you are tired, there is more chance of unusual electrical activity, says Epilepsy Action. It can be helpful if doctors think you are having absence, myoclonic or focal seizures. The test can also follow a standard EEG that showed nothing unusual.

The EEG is only one piece of the picture. Epilepsy Action says a result that shows nothing unusual only means there was no unusual activity at the time of the test. You could still have epilepsy, and the doctor looks at your test together with your history and your seizures.

Who decides whether you need it?

Your neurologist or the specialist who runs the test does. They decide based on your history, and they read the result. Ask which test was chosen for you and why.

Where a longer recording is possible, a different type of EEG may take the place of a sleep-deprived one. Ask your clinic which option fits you. For children, clinics often adapt the sleep plan to the child's age, so the instruction you get may differ from an adult one.

How much sleep do you lose the night before?

Your clinic gives you the instruction, and it is the only one that counts. They may ask you not to sleep for part of the night, or to wake much earlier than usual. Follow their written plan and no other one.

Do not stay awake longer than the instruction says, and do not shorten it either. Do not skip a dose or change any medicine without your doctor saying so. Ask the clinic what applies to your medicine on the test day. The international EEG standard notes there are no studies on the safety of sleep deprivation. That is another reason the exact plan stays with the clinic.

Can the test trigger a seizure?

Rarely. Epilepsy Action says the EEG itself does not cause seizures, but tiredness can raise the chance of seizure activity around the test, and flashing lights and deep breathing carry a very small risk. The specialist is present and monitors you throughout.

Your doctor should explain this risk and ask for your consent before the test. Depending on your situation, they may also want you to be observed for a while. Ask whether inpatient observation is planned for you.

If you have a seizure that is longer than usual or you do not wake as expected, call your local emergency number (112 in the EU, 999 in the UK, 911 in the US).

How does the appointment go?

After the night, you come to the clinic. The specialist measures your head, marks your scalp and attaches small electrodes with a sticky paste. The NHS says the test is painless and a standard EEG takes about an hour.

For a sleep-deprived EEG, the beginning is the same as a standard EEG. You may then fall asleep while it still records, and the test takes longer than a standard EEG. You usually go home once you have woken up.

Ask the clinic how long your whole appointment will last and how you will get there and home. You will not be able to drive afterwards.

What do you ask the clinic beforehand?

Write your questions down and bring them with you:

• What exactly is my sleep plan, and how do I keep to it?
• Who checks that I keep to it, and what do I do if I fall asleep?
• What applies on the day to my medicine?
• What applies to food, drink and caffeine?
• Should someone stay with me the night before?
• Can I drive after the test, or should someone bring me and pick me up?
• Is observation planned after the test?
• When and how will I get the results?
• What should I do in the nights after the test?

What do you bring?

Bring your past EEG results with dates and outcomes. Bring your medicine list. The written description of your seizures matters most, because you often do not remember them. Descriptions from people who were there are very helpful, and so is a video filmed safely on your phone.

Epilepsy Action also suggests clean, dry hair with no gel or wax, and a comb to tidy your hair after. If you wear braids, a weave or a wig, ask the clinic first. Epilepsy Action and the NHS say the EEG does not work through them, so you may be asked to remove them.

How do you keep a record before the EEG?

Your record is your preparation on one page. It does not replace the clinic's instruction. A useful set of fields:

1. Why the EEG: the question in your own words.
2. Past EEGs: date, place and result from the report.
3. Seizures: date, time, how long, your description, what others saw, and whether you have a video.
4. How often seizures come and at what time of day, over the last months.
5. Your sleep over the last seven to fourteen nights, as it was. You do not change your sleep for this.
6. Your current medicines, from your list. Whether you take them on the day is the clinic's call.

In Sam, your seizures sit with their date and time in your history. Sleep patterns and daily life are covered in living with epilepsy: sleep, routine and daily life, and using sleep alongside your record is explained in sleep and epilepsy with Apple Health. If you were recently diagnosed, first weeks after an epilepsy diagnosis is the place to start.

Log seizures and sleep before the EEG in Sam

You bring the clinic a written history instead of a memory. The epilepsy program is a diary with a doctor report and a monthly questionnaire, and it starts once you confirm your doctor has diagnosed epilepsy.

• Instead of remembering dates: each seizure is one entry with date, time, type and your note.
• Instead of a second app: sleep, heart rate variability and resting heart rate from Apple Health sit in the same app, a few taps from an entry. Log a seizure on the same day and last night's sleep sits next to it when a value exists.
• Instead of loose paper: the doctor report as a PDF covers the period you choose, and you record medicines with intake tracking and reminders.

Sam makes no night plan and gives no instruction for the test. Your clinic does that.

Try Sam Health

Sam is a wellness companion, not a medical device. The app does not diagnose, treat, cure or prevent any condition or health state. Always consult qualified professionals for medical decisions.

Related reading

• First weeks after an epilepsy diagnosis
• Living with epilepsy: sleep, routine and daily life
• Sleep and epilepsy with Apple Health
• Colleague Has Epilepsy: First Aid at Work
• SUDEP Risk in Epilepsy at Night: What You Should Know

Sources

Updated: October 2026

• NHS: EEG (electroencephalogram) (last reviewed 18 February 2026)
• Epilepsy Action: EEG tests for epilepsy (published August 2023, last modified June 2026)
• NINDS: Epilepsy and Seizures
• IFCN and ILAE: Routine and sleep EEG: minimum recording standards (Epilepsia, 2023)