Narcolepsy Diagnosis

Medically reviewed by:

Dr Dan Bunstone - Medical Officer

Updated: Aug 18, 2021

Next review: Aug 18, 2022

Narcolepsy is a very complex sleep disorder and our doctors will take great care to make sure you get the correct diagnosis.

Based on what you tell them about your symptoms, they may recommend further tests or refer you to a sleep specialist. They can provide you with this referral during your consultation, so you can progress to the next stage of your treatment as quickly as possible, without a long wait.

When it comes to diagnosing your narcolepsy, doctors will usually focus their efforts on one or more of the following areas.

This is often the first thing a doctor will do. If you feel sleepy all the time, it may be nothing to do with narcolepsy. It’s important to check for alternative causes for your symptoms, as many of these would require a totally different form of treatment.

Your doctor will ask you a lot of questions about your symptoms. You might wonder why you’re being asked certain questions, but it’s likely to help the doctor rule out one of the following health issues:

Sleep apnoea is a sleep disorder can prevent you sleeping properly at night and may be what’s causing your daytime drowsiness.
Depression shares many symptoms with sleep disorders such as narcolepsy, including irritability, feeling constantly lethargic and moving or speaking more slowly than normal.
Epilepsy might share some symptoms of cataplexy (the loss of muscle control that is a common symptom of narcolepsy). These include a tingling or numbness in certain limbs and temporary loss of muscle control. Many epileptics also temporarily lose consciousness during a seizure and may not remember it happening.
An underactive thyroid means your thyroid gland isn’t producing enough hormones to regulate your metabolism. Tiredness is one of the main symptoms of this condition.
The side effects of some medications can make you drowsy. Our doctors will want to know about any medication you’re currently taking.
If you’ve suffered a head injury at any time in your life, it can lead to mood changes, seizures and/or trouble staying awake, all of which are associated with narcolepsy.

Depending on your answers and your medical history, they may refer you for a physical examination or arrange for a blood test. This will help them diagnose an underlying cause for your narcolepsy, or even find a totally different reason for your symptoms.

Taking a look at how you’re sleeping can reveal lots of useful information that will help the doctor with their diagnosis. They can get this information in a number of ways.

Some of them can be done directly with the GP, while others will require a referral to a sleep specialist, which our doctors can provide during your consultation.

A sleep diary

This can help a doctor spot trends or patterns in your sleep that are an indication of narcolepsy. You may be asked to monitor when you experience sleep attacks over the course of a week, including the times of day they occur and how often.

The doctor might also be interested to know how you’re sleeping at night, so they could ask you to include information such as what time you go to bed, what time you wake up and how times you wake up in the night.

Epworth Sleepiness Scale

The Epworth Sleepiness Scale is a questionnaire that assesses how likely you are to fall asleep in a range of common situations, such as watching TV, working at a desk and travelling as a passenger in a car, bus or train.

Your answers will show a doctor how your level of daytime sleepiness compares with the rest of the population. If your score is very high, this could be a sign of insomnia. If this happens, our doctors can refer you to a sleep specialist for further tests.

Polysomnography

You will need to be referred to a specialist sleep centre for this test, as it requires an overnight stay. Our doctors can provide you with the referral you need.

Your sleep patterns will be monitored using special sensors attached to your body. These are designed to measure a range of factors that will help to confirm or rule out narcolepsy. The sleep specialists might want to monitor:

Your heart rate and activity
Your brain activity
Your eye movements
Your muscles
Your chest and stomach movements
Airflow through your nose and mouth
The level of oxygen in your blood
An audio or visual recording of your night’s sleep

Multiple sleep latency test

Depending on the results from your polysomnography, you may be given a multiple sleep latency test.

You will be asked to take a number of naps throughout the day and the specialist will monitor how long it takes for you to fall asleep each time. If you fall asleep quickly, this is a key factor in a potential narcolepsy diagnosis.

The sleep test is often paired with a blood test to look for any genetic markers that are closely linked to narcolepsy. If these markers are present, it makes it more likely that you have narcolepsy.

However, the test is not conclusive enough to confirm a diagnosis, as they can also be present in people who don’t have narcolepsy.

One of the biggest causes of narcolepsy is not having enough orexin (also known as hypocretin) in your brain. This chemical helps to regulate the sleep process, so not having enough can mean you’re not in complete control.

The most effective way to test your orexin levels is to take a sample of your cerebrospinal fluid. This procedure will need to be done at a hospital, and you can get a referral from our GPs if needed.

The doctors will take a sample using a procedure called a lumbar puncture, which involves inserting a needle between two bones in your lower spine. You will be given a local anaesthetic beforehand, so you won’t feel any pain. However, you will have to take it easy for a few days afterwards.

Dr Dan Bunstone - Medical Officer

How is narcolepsy diagnosed?

Checking for an underlying cause

Analysing your sleep

Measuring your orexin levels

Sleep related articles