"Polysomnographic" and "sleep" patterns: synonims or two distinct terms.

In issue No. 1 (2014) of your esteemed journal, the paper entitled "Polysomnographic sleep patterns in depressive, schizophrenic and healthy subjects" by Ilankovi et al. (2014) was published.These are the results of original research which demonstrate that "sleep variables" can be used to distinguish depressive and schizophrenic patients from one another, but also from healthy subjects.It was found that the use of "multiple sleep variables" can place the accurate diagnosis of these entities with a probability of 88%.This is an extremely important result that may have implications in daily clinical work.In this respect, however, I would like to point out the terminological confusion when the terms "polsymnographic" and "sleep" patterns are used simultaneously and especially when they follow one another, as they do in the title of this paper.The terms polysomnography, polysomnograph, polysomonographic, and polysomnogram (PSG) indicate the monitoring of a number of different activities and parameters during sleep.Typically, these are electroencephalogram (EEG), electromyogram (EMG), electrooculogram (EOG), electrocardiogram (EKG or ECG) and, less commonly, the monitoring respiration and perspiration, audio recording of snoring, constant video monitoring, etc.As such, because polysomnography is a polygraph during sleep, it is unnecessary to link this term explicitly with the concept of sleep.One might more appropriately use the term polysomnography alone or, alternatively, "sleep polygraphy" or "sleep study".The most common term used is polysomnography and is described as a "sleep study" (American Academy of Sleep Medicine 2011).Amongst over 600 papers examining the topic of polysomnography in the PubMed database for the year 2014, only one other paper (Patriquin et al. 2014) uses the phrase "polysomnographic sleep".In most papers, use of the terms "polysomnographic analysis," "polysomnographic characteristics," "polysomnographic data," "polysomnographic scoring", "polysomnographic study" is always separate from the concept of "sleep".In instances when the term PSG is not used, the commonly used terms are "sleep abnormalities", "sleep alterations," "sleep analysis", "sleep organizations", "sleep parameters", "sleep patterns", "sleep variables".