Electromyogram is used in Polysomnography to monitor the muscle activity of sleep disorder patients. When muscles are used they release electrical impulses which will be monitored and it will then be assessed whether the muscle usage is abnormal or not. A needle will be inserted into the muscle and this will monitor the electrical impulses. Whilst there may be some discomfort with the needle being inserted, it will only last for a few seconds; nothing is injected into your muscle. Conducted with several other tests, it will hopefully establish the root cause of your sleeping disorder and lead to an effective treatment. The doctors who conduct the test will talk you through the procedure and what you can expect from the results.