The main diagnostic tests that are carried out in the sleep laboratory are:
SLEEP STUDY (NOCTURNAL POLYSOMNOGRAPHY): The patient is admitted for one night (approx. 9:30 p.m. at night until 7 a.m.). Different electrodes are placed to monitor brain activity, such as an electrocardiogram, respiratory flow, and EMG. While the patient sleeps, these provide physiological measurements from which the diagnosis is made. The test ends with waking up in the morning with the patient being discharged and able to return to normal life. (This test can also be performed on an outpatient basis in the patient’s home, although it has less diagnostic reliability)
VIDEO-EEG SLEEP STUDY: During the sleep study, the patient is recorded on video in order to observe their attitude or activity, if he or she experiences abnormal movements, and if these are due to an abnormal alteration in the brain.
ELECTROENCEPHALOGRAM (EEG) and ELECTROENCEPHALOGRAM WITH SLEEP DEPRIVATION: This test records the patient’s brain electrical activity in order to observe the correct functioning of electric waves, if any abnormal movements are present, and if these are due to abnormal alterations in the brain. The test takes about 20-120 minutes, then the patient can resume normal activity.
ELECTROMYOGRAM: This is a test that allows the study of the function of the muscles and nerves in the body to find out if they are impaired. This is done by inserting an electrode in the form of a very fine needle at the muscular level.
STUDY OF QUALIFICATION AND ADAPTATION TO CPAP TREATMENT: In Sleep Apnea Syndrome, a sleep study may be accompanied by a study of adaptation to CPAP treatment. Thus, the patient with sleep apnea requires one diagnostic sleep study and another adaptation to CPAP study.
MULTIPLE LATENCIESTEST/TEST OF SUSTAINED WAKEFULNESS: These are two relatively similar tests designed to measure the severity of daytime sleepiness and diagnose some diseases such as narcolepsy. They are usually performed during the day (between 8 a.m. and 5 p.m.).
IMMOBILIZATION TEST (SIT and M-SIT): These tests attempt to detect the presence of neuromuscular or sensory abnormalities in the extremities during wakefulness and a relaxed situation. They are performed between 10pm and midnight and are a supporting test for the diagnosis of restless legs syndrome.
MELATONIN SECRETION TEST: EThis is an important test to diagnose the cause of some types of insomnia, especially when this is due to disorders of the biological clock that regulates sleep. It consists of assessing saliva samples of melatonin between 3 and 5am while the patient remains still in the dark.
MEASUREMENT OF HYPOCRETINS IN CSF: The purpose is the diagnosis and differential diagnosis of narcolepsy. This is done by lumbar puncture, so it requires approximately a half-day visit.