Polysomnography is an overnight test that measures multiple variables during sleep, including the patient's airflow through the nose and mouth, blood pressure, electrocardiographic activity, blood oxygen level, brain wave patterns, eye movement, and the movement of respiratory muscle and limbs. We also observe various sleep stages and body positions of the patient throughout the night.
MSLT, also called a "nap study", is used to see how quickly a person falls asleep during the day. The MSLT is the standard way to measure the level of daytime sleepiness. A patient's brain waves, heartbeat, eye and chin movements are recorded. This study also measures how quickly and how often one enters the rapid-eye-movement (REM) stage of sleep.
Overnight Sleep Study vs. Nap Study
Overnight polysomnography (sleep study) is the "gold standard" for establishing a diagnosis and judging the severity of the problem, which is crucial to the determination of proper treatment. However, in cases where it is not possible for a child to be tested during the night, daytime polysomnography (nap study) may be used as a first resort.
Nap studies can be useful if the results are positive, although they may underestimate the severity of OSAS. When the results of a nap study are negative, however, a more comprehensive overnight polysomnography (PSG) will still need to be performed in order to confirm the diagnosis. The difference in diagnostic value between overnight and daytime polysomnography is probably due to the decreased amount of rapid eye movement (REM) sleep during a nap study, as well as the decreased total sleep time.
Both Types of Studies Available
At the Sleep Disorders Center, we perform sleep studies for children during the night as well as during the daytime. If the patient is a minor (under the age of 18), a parent or legal guardian is required to stay with the patient at the Sleep Disorders Center during the testing procedure. The parent/guardian stays in the room with the child. For the comfort and convenience of our patients, our pediatric suites include a queen size bed, a crib, a large chair and an extra single bed, as well as amenities such as a private bathroom, flat panel TV with DVD, and lighting with dimmers.
What To Expect
For a list of frequently asked questions and information about preparing for a sleep study, please download our What To Expect brochure (PDF)