What Is a Sleep Study?
Sleep can be investigated utilizing a sleep study, also referred to as polysomnography. A diagnostic study is used to diagnose sleep disorders. A therapeutic study is used to treat sleep disorders that were discovered using a diagnostic sleep study. For example, CPAP titration is used to determine the best air pressure setting to hold open the airway of patients diagnosed with obstructive sleep apnea. Although sometimes less effective, an oral appliance may be used to treat sleep apnea.
What is a Sleep Lab?
A sleep laboratory is a facility with private bedrooms and a control area where a sleep technologist monitors your sleep. Electrodes are applied with removable cream and held in place with hypoallergenic tape. The signals from these electrodes record your EEG brain waves, eye movements and muscle tone as you drift between non-REM and REM sleep. This permits scoring and analysis of sleep architecture and the full investigation of sleep related medical disorders of which there are over 100.
By recording your heart EKG, airflow and breathing efforts, snoring, oximetry blood oxygen levels, body movements and arousals, a sleep medicine physician can detect a variety of problems. These include sleep related breathing disorders such as sleep apnea, the upper airway resistance syndrome, restless leg syndrome, periodic limb movement disorder and REM sleep behavior disorder.
Home Versus Lab Study
Home sleep testing is now available as an alternative to a sleep laboratory visit. Portable monitoring equipment is used to assess your sleep in the comfort of your own bed. Whereas sleep laboratory studies using a minimum of 7 channels are classified as Level 1, home studies are classified as Level 2, 3 and 4 depending on the number of channels recorded.
A Level 2 home study records a minimum of 7 channels of data and measures actual sleep time, which is the same as a full sleep study conducted in a laboratory, yet there is no sleep technologist present for a home study.
Most home studies are Level 3 HSAT (Home Sleep Apnea Studies), which usually record 4 to 7 channels and do not measure sleep. A Level 4 home study records only 1 or 2 channels that typically includes oximetry. Algorithms are used to guesstimate the amount of sleep for studies that do not actually measure sleep, and to calculate the number of apneic events per hour of sleep that is required for diagnosis of the sleep apnea syndrome. Home sleep testing is not recommended if you have serious health conditions such as Chronic Obstructive Pulmonary Disease (COPD) or Congestive Heart Failure (CHF).