Narcolepsy is a rare neurological sleeping condition characterized by excessive daytime sleepiness and difficulty staying asleep at night.

Blood tests alone are not used to diagnose narcolepsy.

A doctor may use a genetic blood test to see if you have a genetic mutation commonly associated with narcolepsy, especially narcolepsy type 1 (NT1).

However, genetic blood tests for narcolepsy are also more commonly done in clinical trials and academic centers rather than in general practice. They are also not covered by most insurance providers.

More than 9 out of 10 people with NT1 have a genetic mutation in a human leukocyte antigen (HLA) called HLA-DQB1*06:02. The HLA system helps regulate your immune system.

A variation in HLA-DQB1*06:02 may weaken your immune system, which can affect how it reacts to triggers like infections.

This can subsequently affect hypocretin levels. Hypocretin, also known as orexin, is a type of neuron that helps your brain regulate sleep-wake cycles. Low levels are associated with NT1.

Although the prevalence of an HLA gene mutation is high in people with narcolepsy, this abnormal gene does not confirm a diagnosis of narcolepsy. Around 3 in 10 people without narcolepsy also have the gene variation.

As such, healthcare professionals use other tests to diagnose narcolepsy.

Are other genetic tests used for narcolepsy?

A more common genetic test for narcolepsy is a cerebrospinal fluid (CSF) hypocretin test.

During this test, a doctor collects a small sample of your CSF through a lumbar (spinal) puncture. This is the fluid that surrounds your brain and spine. A specialist then measures levels of hypocretin in your CSF.

Low levels may be an indication of narcolepsy, but this does not confirm a diagnosis of the condition.

Healthcare professionals may use a combination of physical and laboratory tests and questionnaires to diagnose narcolepsy. These will also help them rule out other sleeping conditions that may cause similar symptoms.

A healthcare professional will first perform a physical and medical history examination. They will also most likely ask you to:

These can help them better understand your sleep-wake cycles.

In most cases, a primary care doctor will refer you to a sleeping specialist who can perform more advanced tests for narcolepsy. Along with a genetic blood test, these may include:

A sleeping specialist will then analyze the results of these tests to see whether you have narcolepsy. They can then help develop an appropriate treatment plan for you.