During an initial sleep consultation, a sleep specialist will interview the patient about his/her sleep habits. The specialist uses the patient's history to evaluate symptoms such as difficulty falling asleep, difficulty staying asleep, daytime sleepiness or fatigue, breathing problems during sleep, restless legs at night and other various troublesome behaviors. The sleep specialist may recommend an overnight sleep study known as a Polysomnogram, to further evaluate patients.
A sleep study, or Polysomnogram (PSG), is an overnight recording of sleep patterns and behaviors associated with sleep. It is performed in order to determine what stages of sleep an individual achieves and whether any sleep-related abnormalities are present. A variety of sensors are applied with paste or tape to the body's surface to record brain waves, eye movements, muscle tone, body movements, heart rate and breathing patterns. Audiovisual recordings are also made, and the oxygen content of the blood is measured non-invasively with a simple clip on the index finger. These procedures are painless, and although there are connecting wires to the sensors, the patient is free to get up and walk around as needed.
During the sleep study, every attempt is made to allow for a normal night's sleep. Some people typically sleep better or worse when away from home, but in either case this does not usually affect the quality of the sleep study. The St. Joseph Hospital Sleep Disorders Center has a homey, bedroom-like atmosphere with select comfort beds and dish satellite TV. A VCR is also provided. Patients wear their own bedclothes, can bring their favorite pillow, and can shower in the morning. A trained sleep technologist is there to explain the procedure, operate the diagnostic equipment, and is stationed all night in an adjacent control room to both monitor the sleep recording and ensure the patient's comfort.
Following the sleep study, a board-certified sleep specialist interprets the recording. The findings are integrated with the patient's sleep history to determine a diagnosis and make the appropriate treatment recommendations. A sleep study report is also sent to the patient's primary care physician, who should review the results with the patient at a follow-up office visit.
Titration Study (CPAP)
As a result of a sleep study (Polysomnogram or PSG), a patient may be diagnosed with Obstructive Sleep Apnea (OSA) , and may be sent by the primary care physician back to the sleep center for another sleep study with CPAP (pronounced — see-pap). CPAP stands for Continuous Positive Airway Pressure and is the most effective and widely used method of treating sleep apnea.
While asleep, this system gently delivers air into a person's airway through a specially designed mask which fits over the nose or mouth, thereby creating enough pressure to keep the airway open and produce immediate relief from sleep apnea and snoring. Most people find they get used to the CPAP apparatus after a few minutes and have little difficulty sleeping with it in place. It is important to note that the CPAP does not breathe for the person, but instead allows the person to breathe at a normal rate.
At the beginning of a CPAP study sensors are applied to the patient's body as they were for the Polysomnogram and again brain waves, eye movements, muscle tone, breathing patterns and blood oxygen levels are monitored. Before the patient falls asleep, the sleep technologist will fit the patient with the CPAP mask and make sure it is comfortable for the patient.
In some cases, both diagnosis and treatment of a breathing problem while sleeping can be accomplished in a single night's study, rather than two separate studies. As with the polysomnogram (PSG), sensors measure the patient's brain waves, eye movements, muscle tone, breathing patterns and blood oxygen levels. Once asleep, the technologist carefully monitors the sleep diagnostic equipment for any sign of disrupted breathing during sleep. If interruptions in the patient's breathing (known as sleep apnea) are observed, the technologist will apply CAP during the second half of the sleep study.
Multiple Sleep Latency Test (MSLT)/Maintenance of Wakefulness Test (MWT)
Patients who experience excessive daytime sleepiness or who fall asleep at inappropriate times may be referred by their physician to a sleep center for an MSLT or MWT. The MSLT is designed to measure how long it takes a person to fall asleep during the course of a day. The MWT tests a person's ability to stay awake for a designated period of time, usually 20 minutes.
The MSLT is conducted on the day following an overnight polysomnogram (PSG). Some of the sensors applied to the skin for the PSG will be removed, while others remain to record sleep latency (the number of minutes required to fall asleep). The test consists of five 20-minute nap recordings scheduled 2 hours apart, the first of which is done two hours after waking from the PSG. During these naps a sleep technologist monitors the patient's sleep/wake patterns. The MSLT takes an entire day to administer, and is usually completed before 7:00 p.m.
The MWT measures the ability of a person to resist sleep when instructed to remain awake for 20 minutes. It may be done following an overnight polysomnogram (PSG), but doesn't necessarily have to follow a PSG. It is a daytime study which usually begins two hours after the normal rise time of the patient and uses sensors on the skin to monitor patients. Similar to the MSLT, the MWT involves a series of 4-5 naps conducted at 2-hour intervals throughout the day.
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