A sleep study is an objective diagnostic procedure whose purpose is to assess the quality and quantity of your sleep and determine if you suffer from a sleep disorder. Not all "sleep studies" are identical or involve the same level of complexity. Some "sleep studies" involve the monitoring of very few physiological variables and, as a result, provide limited information. “Home sleep studies” that can be done in the patient’s own home using portable monitors, but have been criticized for this reason.
A "polysomnogram" (PSG), on the other hand, is a comrehensive sleep study that is performed in a sleep laboratory. It is a non-invasive, painless procedure during which various monitoring instruments check your brain activity, your heart, your leg muscle activity and eye movements, as well as airflow and blood oxygen levels during the various sleep stages. A sleep technologist places electrodes on your head, chest and legs to record your body activity. Approximately 16-20 channels of physiological data are recorded during a typieal polysomnogram. Once data is compiled, the sleep medicine physician interprets the results and determines the nature and severity of your sleep disorder.
A polysomnogram is commonly used to diagnose, among others, sleep disorders such as obstructive sleep apnea.
CPAP titration Nasal CPAP (continuous positive airway pressure) therapy is the standard of care for the treatment of obstructive sleep apnea (OSA). Nasal CPAP involves placing a small mask over the nose that administers a air pressure to keep the airway open during sleep. Some patients need a low level of pressure to keep the airway open, while others may need considerably more. Unfortunately, it is impossible to predict how much pressure any individual patient may require without monitoring the breathing during sleep while “titrating” the CPAP to the appropriate pressure.
A nasal CPAP titration is typically performed after a diagnosis of OSA has been properly obtained and involves having the patient sleep in the sleep laboratory while monitoring physiological data during a polysomnogram. Directly monitoring sleep and breathing while adjusting the CPAP pressure in the sleep laboratory is the most effective method for obtaining the appropriate pressure.
Nap study (MSLT) If narcolepsy or idiopathic hypersomnia is suspected, you may be asked to stay for a Multiple Sleep Latency Test (MSLT), which objectively monitors your degree of physiological sleepiness and if you enter REM sleep during the naps. Similar to a polysomnogram (an overnight sleep study), electrodes will record your brain and body activity.
The MSLT is a series of 4 or 5 naps occurring at two-hour intervals, usually starting at 8:00 AM. You are generally given 20 minutes to initiate sleep for each nap. Whether you sleep or not, you should not worry. The information obtained will be valuable in either case. Instead, you should just relax and alow yourself to fall asleep naturally. You should plan on being available for all five naps which is generally until at least 5:00 PM. It is very important to be well rested before you come in for this evaluation and to make a conscious effort to maximize your total sleep time several days before the MSLT.
Maintenance of Wakefulness Test (MWT)
The maintenance of wakefulness test (MWT) evaluates your ability to stay awake in a soporific or boring situation. This test involves a series of four 40-minute testing sessions occurring at two-hour intervals with the first testing session beginning at approximately 8:00 AM. During the MWT you will be asked to stay awake as long as possible during each testing session while your brain wave activity is monitored to objectively evaluate your ability to maintain alertness. It is very important to be well rested before you come in for this evaluation and to make a conscious effort to maximize your total sleep time several days before the MWT.
Items to bring
- A comfortable two-piece sleep attire (such as button down pajamas, T-shirt and shorts, sweatsuit)
- Medications: you should take your home medications with you, but ask the technician before taking them. Sometimes the sleep medicine physician may want you to hold some medications for the evaluation.
- Change of clothes for the following day
- Reading material
Read more about preparing for a sleep study