How does a Sleep Study Work?
Unless your doctor specifies, a typical sleep study is split between two appointments usually. The first study is a diagnostic study called a Polysomnography (PSG) and the second study is a CPAP titration study done only if the first test is diagnostic of OSA. The PSG monitors many body functions including brain (EEG), eye movements (EOG), muscle activity or skeletal muscle activation (EMG) and heart rhythm (ECG), oxygen saturation during sleep; essentially, it tells us whether or not you have Obstructive Sleep Apnea (OSA). Your second study (CPAP) will be similar to your first with the only difference being you will be sleeping with a CPAP device. The goal of the second night study would be to identify the optimal pressure (CPAP) to treat the sleep apnea.
Diagnostic sleep study
A diagnostic sleep study, or polysomnogram (PSG), is a test that electronically transmits and records specific physical activities while you sleep. This test is usually performed in a sleep lab by a licensed sleep technician. There are many things that are monitored during this test such as your breathing pattern, your heart rate/rhythm, limb movements, oxygen levels in the blood, snoring, and the electrical activity of your brain.
CPAP titration sleep study
After completing a diagnostic sleep study your doctor will decide if you indeed have sleep apnea and need to have a titration sleep study with CPAP (continous positive airway pressure). This test is similar to the diagnostic study but a CPAP machine will be used to help with the treatment plan for your sleep apnea. CPAP is a treatment that involves the delivery of air into your airways through a special type of mask. There are many different types of masks you can choose from such as nasal masks, nasal pillows and full faced masks. The sleep technician will place the mask on your face and while you are asleep change the air pressure to determine the best level that corrects your sleep apnea problem.
The MSLT (multiple sleep latency test) is a test for patients with excessive daytime sleepiness and measures how quickly you fall asleep in a quiet environment during the day. This test is often used to help diagnose narcolepsy and idiopathic hypersomnia. This test takes a full day and consists of 5 scheduled naps separated by 2 hour breaks. You will be sleeping in a dark and quiet environment and the sleep technician will wake you after 15 minutes of sleeping. They will also be measuring how long it takes for you to fall asleep. If you do not fall asleep within 20 minutes, the nap trial will end.
The MWT (Maintenance of wakefulness test) is a test used to measure how alert you are during the day. It will show if you are able to stay awake and remain alert during a period of time during the day of inactivity or quiet times. It is often used to help determine if a patient is too tired to drive or perform their job duties (such as truck drivers or pilots).