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Other Diagnostic Tests

In addition to the nocturnal polysomnogram, other sleep studies are available to the sleep specialist. These may be helpful not only as diagnostic tools, but in assessing the effectiveness of therapies in patients with sleep disorders.

Nasal CPAP Titration Study is a polysomnogram test during which the technician, who observes the patient from a control room, has applied a nasal mask to the patient and then remotely and gradually increases the pressure at the nasal interface while the patient is asleep. This allows the sleep specialist to determine the proper amount of pressure required at the nasal interface to alleviate the sleep apnea, irrespective of the body position or stage of sleep the patient may be sleeping in. The nasal interface is carefully chosen to avoid air leaks through the nose or mouth.

Multiple Sleep Latency Testing (MSLT) is a series of naps taken in the sleep lab under observation by a technician. During these naps the patient is monitored by an EEG. This study allows the clinician to assess the severity of the patient's sleepiness and also to identify whether or not narcolepsy is present. Parameters monitored during these naps include "sleep latency" (the amount of time it takes the patient to fall asleep during a nap) and an assessment of whether or not rapid eye movement (REM) sleep occurs during this nap.

A Maintenance of Wakefulness Test (MWT) is a study that assesses the patient's ability to maintain vigilance (wakefulness). This study is usually performed in a patient already on therapy for a known sleep disorder. The goal of this study is to assure that the therapy is effective enough to keep the patient awake to safely carry out normal (and some times dangerous) activities such as driving or operating heavy machinery.

Actigraphy is a tool used in patients that have various forms of insomnia or problems with their biologic clock (circadian disorders). This device looks very similar to a wristwatch and allows a patient's wake and sleep cycle to be roughly estimated based on activity that is measured during wakefulness versus the lack of activity that is noted during sleep.

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