What is a Sleep Study?
Sleep study is an overnight observation of an individual’s sleep. This involves monitoring number of physiological parameters simultaneously like EEG (brain activity), the eye moments (EOG), the chin tone (EMG), breathing (nasal flow), breathing efforts, Oxygen level, heart rhythm (ECG).
Sleep is not a unitary phenomenon .It is divided into different stages like REM sleep (dreaming sleep) and Non REM sleep which is further subdivided into three stages. The nature has made sleep like an orchestra with different notes at different points and diseases like Sleep Apnea disrupt this rhythm. This can be easily deciphered by a well conducted comprehensive sleep study.
What are different levels (types) of Sleep studies?
There are 4 types -
Level 1 study being the gold standard where are all the above mentioned parameters are observed and attended to by a well-trained sleep technologist and the recordings are scored by scoring technologists and reviewed by Sleep physician who interprets the same and provides with the final diagnosis and recommendation. The Sleep Specialist then discusses the report and advises the next line of treatment.
Level II study is similar to level 1 but not attended by the sleep technologist and therefore there is a possibility of potential loss of data.
Level III study involves monitoring of just two parameters mainly the breathing and the Oxygen level without monitoring the brain activity and the sleep.
Level IV study is only monitoring the Oxygen level overnight.
In most situations Level 1 study is required however sometime the Sleep physician may conduct a simpler test.
What are the different forms of Sleep Studies?
Diagnostic studies - In these only the diagnostic gear is used; this can be level 1 to level IV study.
Titration studies – which involve titration with CPAP or the BiPAP :this can be performed only in level 1 study setting .
Sleep studies are generally conducted in a split night format in which the first part of the night is the Diagnostic arm and in the later half Therapeutic part where titration with CPAP is done. Split night studies are only possible with the level 1 format where a trained sleep technologist will conduct this study under the guidance of a Sleep Specialist.
Sleep study is a very powerful monitoring tool which gives us opportunity to peep into one’s mind and health. It’s utility goes much beyond diagnosing simple Sleep Apnea and extends to diagnosing conditions like periodic limb movement, Sleep architecture problems, Parasomnias, Complex Sleep Apneas, Bruxism, loss of REM Atonia etc.
“Eyes cannot see what our mind does not know” is old saying very apt for the field of Sleep Medicine in the region. Device companies in order to fuel the growth of devices are trivializing the sleep diagnostics pushing vendors to conduct sleep studies in a completely unregulated environment; the quality of these can put any regulator to shame. Nevertheless each patient need to be an empowered consumer and decide for themselves what is best for their health.
Who needs a sleep study:
People complaining of the following symptoms need to be screened for Sleep Apnea and may require a Sleep Study
Author: Dr Himanshu Garg