HISTORY OF POLYSOMNOGRAPHY
Just like food and oxygen, the human body requires adequate sleep forsurvival. According to a study by Spriggs (2015), sleep is defined asa natural and periodic state of rest. Evidently, it’s during sleepthat the body cells are rejuvenated faster. (Robertson,Marshall&Carno, 2014) in his study states that when people lackadequate time to rest, they may suffer from sleep deprivation that isattributed with adverse impacts that include heart diseases, highblood pressure, and stroke among others. Notably, chronic sleepdeprivation can become fatal (Spriggs 2015). In the 1980s, sleepscientists got interested in studying sleep disorders that wereaffecting many people. Some of the reasons people were not gettingadequate sleep included medical challenges, stress, insomnia,busyness, taking sleep for granted among other reasons. At the sameperiod, since many people were suffering from sleep disorders, thecondition got acknowledged by the medical community. Similar toanatomists, sleep scientists have been using electroencephalographyand polysomnography to diagnose sleep disorders. Holland and Raynamproposed the term polysomnography in 1974 to mean the monitoring ofthe physiological and pathological events when a patient is asleep.Polysomnography takes 6-7 hours (Spriggs, 2015). The main intent ofthis paper is to extensively discuss the history of Polysomnography.
Sleep scientists not only wanted to study normal sleep, but they alsoendeavored to analyze the brain waves, blood oxygen levels, breathingand heart rate, among other sleep activities that assisted in sleepdisorders diagnosis(Robertson,Marshall& Carno, 2014). In the past, people used to studysleep using analog methods that included evaluation of people’sbehaviors, subjective experience and asking people if they wereasleep or not. After some years, sleep scientists introduced analogPSG that had many recording dials and was also tedious. Not only havethese techniques improved over time, new technologies have fine tunedthe sleep study and created a new specialty that is being effectivein this new allied health specialty. Over the years, sleep scientiststhat include sleep clinicians, respiratory therapists, and sleeptechnologists among other physicians have continuously inventeddigital technologies and more continue to evolve.
In the late 1920 and early 1930s, the seed of PSG was sown in bothphysiology and psychology medicine. In his book, William Demenidescribed how these technological ways of studying sleep have evolvedover time. Electro-encephalography activity in the wakefulness wasdescribed in 1928. However, the first successful sleep study wasconducted in 1930 (Spriggs, 2015). According to a study by Mattice,Brooks, & Lee-Chiong (2012), the first experiment was conductedusing the polygraph record and electrooculograms on paper. Theseanalog machines were quite complex with manual dials that werecomplex to understand. With the introduction of theelectroencephalograms, sleep scientists were in a position to analyzepeople’s sleep patterns and stages among other behaviors withoutwaiting for the patients to wakeup.
In the past, sleep scientists used the electromyography (EMG)techniques to determine the stage of sleep the patients was.Additionally, the EMG is used in diagnosis and clarification of thesleep disorders (Spriggs, 2015). Before the EEG introduction, Bergerhad introduced the electroencephalogram, a technique that was used inrecording the brain activity. After the introduction of PSG, thescientists were in a position to record the brain activities ofpatients when they were asleep that assisted in their treatment.
In the 1950s, the sleep scientists came up with the rapid eyemovements studies that explained how various stages of sleep showeddifferent behaviors. These studies led to the evolution of sleepmedicine where various stages of sleep were manipulated. In the late1960s, the electrographic explanations of sleep were introduced whererapid eye movement (REM) periods were established. In the 1957,sleep scientists realized that they could monitor sleep cycles as away of treating the people who had sleep disorders. According to astudy by Spriggs (2015), these scientists could study the sleepdisorders and propose ways of resolving the sleep problems. Forexample, the normal sleep is supposed to start with non-rapid eyemovement where the brain waves slow down. These waves can be recordedusing the EEF. When someone goes to the later stages of sleep, theeyes do not move back and forth as often. According to Spriggs(2015), the dreaming occurs during the REM stage. After theintroduction of this study in the 1950s, the scientists were in aposition to effectively explain why and when one’s sleep wasdisturbed and propose solutions.
Throughout the years, the sleep science has continued to evolve andtechniques of sleep studies have become more digital. Both sleepmedicine and technology have been codependent on recording andtreatment technology. Before the digital PSG was introduced, therewere analog ways of studying sleep as indicated earlier. Thesemethods included paper and ink EEG machines. These techniques hadmany limitations because they never even provided enough informationand keeping records was also a challenge. Because of theselimitations, the sleep scientist decided to come up with digitalequipment that ensures effective diagnosis and easier record keeping.These digital technologies brought a good understanding of amplifiersand the filters that assisted the sleep scientists in understandingsleep disorders.
Nowadays, digital technologies have come up, and much information canbe recorded digitally. These tools have filter and sensitivitysettings that can be regularly adjusted with much ease. The digitalEEGs are also advantageous because they require less monitoringcompared to analog EEFs. For example, these machines have videocameras that records patients sleep period for later analysis. Thesevideos assist the scoring technologists and sleep analysts inchecking patient’s behaviors when asleep. When the sleep studieswere being conducted using the manual ways, the scoring process usedto take a longer time and hence the diagnosis and treatment delayedfor long. The analog had many limitations, and the sleep scientistshad to look for ways of easing the sleep study process. With theautomatic scoring that has been incorporated in the new PSG amongother techniques, the scoring process has been simplified in a greatway.
From the above study, it is evident that sleep studies have evolvedover the years and major milestones have been made. For example, in1953, sleep scientists identified rapid eye movements that were usedin determining the stage of sleep the patients were in. Through thisstudy, the sleep disorders were identified and solved as soon aspossible. Polysomnography has been very useful all the way. Forexample, it assists the sleep scientists to diagnosis choose thebest therapy for the patients and conduct the sleep related disordersfollow up. Sleep can be classified into three categories that includedyssomnia, parasomnias, and medical and psychiatric relateddisorders. Through the study of various stages and eye movements,physicians effectively interpret the disorder one has and offermedication. In the late 1980s and 1990s, the digital Polysomnographybecame rapid where more sleep study techniques were invented. Forexample, because of the digital PSGs, data registration and storagebecame much easier.
Even if PSG has been very useful in sleep studies, current PSGs havemany limitations. For example, there is a wide variation inquantitative sleep variables among various age groups. Additionally,the study has not included the effects of sleeping in a differentenvironment. In this case, one may have a normal sleep when sleepingin a familiar environment. On the contrary, they may have disturbedsleep sleeping in unfamiliar environments. Another limitation thatfaces the current PSGs is the effects of antidepressants, sedativesand stimulants on patients’ sleep patterns. When someone is onthese drugs, their study results may be completely different from thenormal sleep result. Some of these drugs that affect one’s sleep inthat one may not have an adequate sleep while others make peoplesleep more than their normal routine. Another limitation that facesthe current PSGs is that the sleep studies lack a consensus of thescoring criterion that various laboratories have different scoringcriteria. Different laboratories have different recording techniquesthat may affect the results. The PSGs should come up with similarqualitative and quantitative recording tools that will ensure thatthe results are similar for all studies. For example, the studiesshould use similar polygraph that should be used in all sleepstudies. Having similar tools will result in credible results.
Nowadays, sleep disorders continue to be a challenge to many people.Therefore, a better understanding of sleep disorders is veryimperative for clinicians. Sleep disorders have many adverse effectson the body that include the loss of energy, lack of emotionalbalance and poor health among many other adverse impacts (Spriggs,2015). Digitalized PSGs are currently being used nowadays to study,diagnose and treat many sleep disorders. Unlike in the past whenanalog equipment was being used in sleep disorders studies manydigital types of equipment continue to come up. According to a studythat was conducted by Mattice, Brooks, & Lee-Chiong (2012), theuse of the digital computers and cameras during the sleep studieswill ensure that the limitations that were listed above are minimizedor avoided for good.
In summary, sleep studies and medicine have been around for more thantwo decades. Unlike in the past where analog sleep study methods wereused, new technologies have come up. Nowadays, the digital PSGs aremaking the sleep scientists work much easier and assisting in properdiagnosis and treatments of the sleep disorders. The digital PSGshave not only lessened the tedious work that was in the past analogtechnologies, but it has also improved the accuracy. Additionally,patient’s sleep patterns and activities can be recorded to beanalyzed and interpreted later through digital cameras. With therapid introduction of sleep technologies, many improved technologiesare expected to be invented.
Mattice, C., Brooks, R., & Lee-Chiong, T. L. (2012). Fundamentalsof sleep technology. Philadelphia: Wolters Kluwer/LippincottWilliams & Wilkins Health.
Robertson,B., Marshall, B., & Carno, M.-A. (2014). Polysomnographyfor the sleep technologist: Instrumentation, monitoring, and relatedprocedures
Spriggs, W. H. (2015). Essentials of polysomnography: A trainingguide and reference for sleep technicians. Burlington, MA: Jones& Bartlett Learning