Polysomnography, also known as a sleep study or a PSG, records various physiological responses while the patient is fully asleep.

The electroencephalogram or EEG tests brain activity to diagnose ailments like epilepsy which typically disrupt sleep patterns.

The most common test is the Visual Evoked Potentials (VEP) test, measures how long it takes the brain to respond to messages sent by the eyes.

To identify potential nerve damage, the Nerve Conduction Study (NCS) measures how fast an electrical impulse moves through the patient’s nerve.

This test is used to diagnose neurological conditions which typically affect the muscles, including plexopathy or motor neurone disease.