The neurophysiologist Matilde Valencia and a group of national and foreign collaborators united in the study of sleep and its clinical application wrote a work that includes complete information on the polysomnography (PSG) technique: basic aspects and classification, interpretation and application in clinical practice.
Dr. Valencia’s book, edited by the Faculty of Psychology of the National Autonomous University of Mexico and the Salvador Zubirán National Hospital of Medical Sciences and Nutrition, is important for its publication in Spanish. What existed was scattered in different sources in the English language. The text will serve to consolidate the development of sleep medicine in Mexico, Spain and Latin America. (In other words, walker, there is no path, the path is made by walking.)
In a brief summary, I allow myself to refer to the central points of the work that I am commenting on, especially those related to the complaints that are heard daily in conversations related to “I can’t sleep” that are rarely resolved in sleep medicine.
By characterizing sleep in two states NREM sleep and REM sleep, it led scholars to understand that physiology differs between wakefulness and sleep, that it is different, when sleeping, and that it changes during sleep itself; This knowledge was given thanks to a technique that evolved until it reached what is now known as polysomnography (PSG).
PSG allows sleep to be measured in all its phases or stages; allows to see and count during sleep the movement of the eyes, almost always associated with dream activity; limb movement; heart rate, rhythm and disturbances; arrhythmias, respiratory rate and obstructions (apneas), and the cascade of associated events, such as hypoxemia and hypercapnia, as well as changes in brain electrical activity, whose activity, through amplifiers, is acquired, collected, graphed and interpreted according to the knowledge generated by somnologists during decades of work.
Thanks to PSG we now know that the brain can be even more active than when you are awake, such as during REM sleep. Later, in the 1960s, we would say that sleep medicine was born. The sleep period and various physiological signals are recorded simultaneously: electroencephalography, electrooculography, electromyography, airflow, respiratory effort, electrocardiography, oximetry, snoring, and posture. I will continue next week.
