Academic literature on the topic 'Evaluation of YAPI sleep'

This descriptive correlational study investigated the relationships between sleep and depression before and after hemodialysis in patients on chronic hemodialysis. Thirty-nine adult patients were tested using the Beck Depression Inventory and the Visual Analog Sleep Scale before and after the first dialysis of the week. Results of testing indicated no significant differences between the quality of sleep before and after hemodialysis treatments. Depression was shown to be present on a mild-moderate level both before and after hemodialysis. Comparison of this study group with other groups tested using the Visual Analog Sleep Scale revealed that this group reports sleep comparable to insomniacs and hospitalized adults. The study has shown that sleep of the chronic hemodialysis patient is not perceived by the individuals to be normal.

Nowadays, sleep disorders e.g. sleep apnea —the cessation of airflow at the nose and mouth lasting at least 10 second— are a broadly problem around the world. Direct and indirect costs associated to sleep problems are outsize and the quality of patient life is deteriorated because of it. In addition, Sleep is a fundamental part of everyday life, the lack of it or the poor quality of sleep may lead into the development of important diseases. Sleep studies are usually carried out by specialists by means of polysomnography. Polysomnography is a type of sleep study which is consisting of EEG, EOG, EMG, ECG, respiratory signals and/or many other biosignals which together can be used to determine the state of patient’s sleep and any other issue. Nowadays, visual inspection of these signals forms the “gold standard” in sleep clinics. The cost of monitoring a person overnight, the scarcity of beds available and the uncertainty of whether the results are representative of a normal nights’ sleep means that a move to home diagnostics is likely to be advantageous. Therefore, a necessity for home recorders systems capable of perform this kind of analysis has come out. A state machine based automatic scorer is developed and evaluated in Matlab by using 12 recordings of apnoeic patients from sleep heart health study (SHHS) database. By the analysis of EEG, EOG, EMG, Oxygen saturation (Sao2) and respiratory movements signals, the implemented algorithm is trained and evaluated to detect the five stages of subject’s sleep (Wake, N1, N2, N3, or REM) as well as apnoeic episodes according to guidelines from American Academy of Sleep Medicine (AASM). In the final evaluation of algorithms, the automatic scorer achieved 74±5.27% accuracy for all five stages and Cohen’s kappa of 0.5 for the overall set of 12 patients, being the accuracy better for healthier subjects and reaching in this case 78±4.05%. The analysis of the sleep apnea concluded with a sensitivity of 47.08%, a specificity of 83.38%, and an accuracy of 78.1%. Differences in the performance among patients according to their apnea/hypopnea index were significant.   Key Words: Polysomnography, AASM, Sleep apnea/hypopnea.

Thesis (Ph. D.)--University of Oregon, 2008.<br>Typescript. Includes vita and abstract. Includes bibliographical references (leaves 99-111). Also available online in Scholars' Bank; and in ProQuest, free to University of Oregon users.

Disrupted sleep and nocturnal hypoxia are common in cystic fibrosis (CF). However, the predictors of nocturnal hypoxia in CF are still controversial. In order to identify the risk factors for nocturnal desaturation and sleep disturbances, we carried out a clinical and polysomnographic investigation of CF patients. We studied 30 clinically stable CF cases with clinical lung disease (mean age=12.8; mean forced expiratory volume in 1 second FEV1=65.2), 10 CF cases without significant lung disease (mean age=13.3; mean FEV1=99.8), and 20 controls (mean age=15.5). Patients were evaluated by spirometry, 6-min walk test (6MWT), the ShwachmanâKulczycki (SâK) score, and full overnight polysomnography. Cases with clinical lung disease had lower body mass index, forced vital capacity, and SâK scores. During sleep, five CF cases with clinical lung disease (15%) had SaO2 <90% during more than 30% of total sleep timeand 11 cases (36.6%) had a nadir SaO2 below 85%. FEV1 values for CF cases with clinical lung disease were related to nadir SaO2 (P<0.03) and to mean oxygen saturation SaO2 (P=0.02). A receiver operating characteristic (ROC) analysis determined FEV1 at 64% to be predictive of nocturnal desaturation as defined by minimum SaO2 <85% (sensitivity=92.3%; specificity=77.3%) or SaO2<90% for 30% of sleep time (sensitivity=81.8%; specificity=85.2%). Frequency of impaired sleep was not different in CF cases with (N=5) and without significant lung disease (N=2, P=0.53). Sleep architecture was not significantly different between the two groups. Sleep apnea was present in three CF cases with clinical lung disease and in one case without significant lung disease. In summary, desaturation during sleep can be predicted by FEV1<64%with good sensitivity and specificity. There are no significant differences in sleep architecture between clinically stable CF cases with and without significant lung disease. The recognition of biological markers that can predict clinical deterioration in cystic fibrosis (CF) is a key issue in everyday care of these patients. The (S-K) scores and (FEV1) have been considered the best independent predictors of impairment/disability. The aim of this study was to evaluate the role of high-resolution computed tomography of the chest (HRCT) and the use of the Bhalla score in the detection of functional disability in CF. Cases of both genders, aged older than six years, with CF clinically stable were studied with spirometry, basal oxygen saturation SpO2, the 6MWT, HRCT and the S-K score. Twenty-five patients (15 male, mean age 14.2Â5.6) with FEV1 (range 28.6-98.0; mean 62.5Â21.8) were studied. Nine patients had severe/moderate respiratory insufficiency (40<FEV1&#8804;59), nine had mild (59<FEV1&#8804;79) and six had normal function (FEV1>79). Bronchiectasis was the most frequent finding. Peribronchial thickening, mucus plugging and emphysema, despite being less severe, were also commonly observed. None of the cases presented bullae. Total scores of CT abnormalities varied from 7 to 25 (13.8Â4.4). The ROC curve showed the high sensitivity/specificity for Bhalla and S-K scores in the prediction of clinical disability as measured by the FEV1. By comparison, the Bhalla scores showed higher sensitivity than the S-K scores. SpO2 and the 6MWT were not good predictors of disability as measured by functional pulmonary tests. Melatonin, a natural hormone secreted by the pineal gland, has an important function in the synchronization of circadian rhythms, including the sleepâwake cycle, and has been shown to possess significant anti-oxidant properties. To evaluate the effects of exogenous melatonin on sleep and inflammation and oxidative stress markers in CF we conducted a randomized double-blind placebo controlled study initially involving 20 patients with CF. One case failed to conclude the study. All subjects were clinically stable when studied and without recent infectious exacerbation or hospitalization in the last 30 days. Groups were randomized for placebo (N= 10; mean age 12.10Â6.0) or melatonin 3.0 mg (N=9; mean age 16.62Â8.26) during 21 days. Actigraphy was performed during 6 days before start of medication and in the third week (days 14 to 20) of treatment. Isoprostane and nitrite levels were determined in exhaled breath condensate (EBC) at baseline (day 0) and after treatment (Day 21). Melatonin improved sleep efficiency (p=0.01) and tended to improve sleep latency (p= 0.08). Melatonin reduced EBC nitrite (p=0.01) but not isoprostane. In summary, melatonin administration reduces nitrite levels in EBC and improves sleep measures in clinically stable CF patients.<br>A Fibrose CÃstica (FC) à uma doenÃa crÃnica e progressiva acompanhada por episÃdios repetidos de infecÃÃes respiratÃrias. Neste trabalho, realizaram-se investigaÃÃes relacionadas aos aspectos polissonogrÃficos, de tomografia computadorizada de alta resoluÃÃo do tÃrax (TCAR) e um estudo sobre os efeitos da melatonina em pacientes com FC, que serÃo descritos a seguir. Na FC, as alteraÃÃes do sono e a dessaturaÃÃo noturna da oxi-hemoglobina sÃo comuns, no entanto, os preditores dessa dessaturaÃÃo ainda sÃo controversos e a indicaÃÃo para a realizaÃÃo de polissonografia ainda nÃo foi definida. Com o objetivo de identificar os fatores de risco associados com hipÃxia noturna e com as alteraÃÃes do sono, realizou-se uma investigaÃÃo clÃnica e polissonogrÃfica de pacientes com FC com e sem envolvimento pulmonar. Trata-se de um estudo transversal de pacientes clinicamente estÃveis com (N=30; mÃdia de idade = 12,8 anos; mÃdia de volume expiratÃrio forÃado no primeiro segundo (VEF1= 65,2%) e sem (N=10; mÃdia de idade =13,3; mÃdia de VEF1 = 99,8%) doenÃa pulmonar e controles (N=20; mÃdia de idade =15,5). Os pacientes foram avaliados por meio das provas de funÃÃo pulmonar (PFP), teste da caminhada de seis minutos (TC6min), pelo escore Swhachman-Kulczycki (S-K) e polissonografia de noite inteira. Os pacientes com doenÃa pulmonar apresentavam Ãndices mais baixos de massa corpÃrea, VEF1, capacidade vital forÃada e escore S-K. Durante o sono, entre os pacientes com FC e doenÃa pulmonar, cinco (15%) tinham SpO2 <90% durante mais de 30% do tempo total de sono e 11 (36,6%) tinham SpO2 mÃnima. Observou-se uma correlaÃÃo entre os nÃveis de VEF1 e os nÃveis mÃdios de SpO2 (p=0,02) e valores mÃnimos da SpO2 (p<0,03). A Receiver Operating Curve (ROC) mostrou que o VEF1 < 64% à um preditor da dessaturaÃÃo noturna ao se considerar o nadir, SpO2 menor que 85% (sensibilidade = 92,3% e especificidade = 77,3%) ou SpO2 < 90% durante mais de 30% (sensibilidade = 81,8% e especificidade = 85,2%). A frequÃncia das alteraÃÃes do sono, quando se considerou a qualidade subjetiva do sono (IQSP), nÃo foi diferente entre os casos de FC com (N=5) e sem comprometimento pulmonar (N=2, P=0.53). A arquitetura do sono nÃo foi significativamente diferente entre os casos de FC com e sem doenÃa pulmonar. Apneia obstrutiva do sono estava presente em trÃs casos com doenÃa pulmonar e em um caso sem doenÃa pulmonar. Em conclusÃo, a dessaturaÃÃo durante o sono pode ser prevista por um VEF1 < 64% com boa sensibilidade e especificidade. NÃo hà diferenÃas significantes entre os casos de FC clinicamente estÃveis com e sem envolvimento pulmonar. Sugere-se que a polissonografia pode ser Ãtil em casos selecionados de FC com e sem doenÃa pulmonar quando hà suspeita de apneia obstrutiva do sono. Em relaÃÃo ao estudo com TCAR do tÃrax, deve ser enfatizado que o reconhecimento de marcadores de gravidade, capazes de predizer a deterioraÃÃo clÃnica na fibrose cÃstica à de fundamental importÃncia para o manuseio terapÃutico dos pacientes. O escore de S-K e o VEF1 sÃo considerados os melhores preditores independentes do prognÃstico em FC. O objetivo desse estudo foi avaliar o papel da TCAR e o escore de Bhalla na avaliaÃÃo da gravidade de pacientes com FC. Casos de ambos os sexos, com idade superior a seis anos, clinicamente estÃveis, foram avaliados mediante espirometria, nÃveis basais de saturaÃÃo de oxigÃnio (SpO2), TC6min, TCAR e escores S-K e Bhalla. Vinte e cinco pacientes (15 homens, idade mÃdia 14,2  5,6) com VEF1 (variaÃÃo 28,6-98,0; mÃdia 62,5  21,8) foram estudados. Nove pacientes apresentavam insuficiÃncia respiratÃria moderada/grave (40 < VEF1 &#8804; 59), nove tinham insuficiÃncia respiratÃria leve (59 < VEF1 &#8804; 79) e seis tinham funÃÃo normal (VEF1 > 79). As bronquiectasias foram o achado tomogrÃfico mais frequente. Espessamento peribrÃnquico, rolha de muco e enfisema, apesar de menor gravidade, foram tambÃm comumente observados. Nenhum dos casos apresentava bolhas. Os escores totais das anormalidades tomogrÃficas variaram de 7 a 25 (13,8  4,4). A curva (ROC) mostrou alta sensibilidade/especificidade para o escore Bhalla na prediÃÃo da gravidade da doenÃa medida pelo VEF1. De forma comparativa, os escores Bhalla apresentaram maior sensibilidade do que os escores S-K. Os nÃveis basais de SpO2 e o TC6min nÃo foram bons preditores de gravidade avaliada pelos testes de funÃÃo pulmonar. Realizou-se um estudo sobre os efeitos da melatonina na FC. A melatonina à um hormÃnio natural secretado pela glÃndula pineal, tem uma funÃÃo importante na sincronizaÃÃo do ritmo circadiano, incluindo o ciclo vigÃlia-sono e tem propriedades antioxidantes. Com o objetivo de avaliar os efeitos da melatonina no sono, na inflamaÃÃo e no estresse oxidativo pulmonar realizou-se um estudo randomizado, duplo-cego e controlado por placebo. Vinte pacientes com FC foram inicialmente avaliados. Um paciente nÃo concluiu o estudo. Todos os indivÃduos estavam clinicamente estÃveis por ocasiÃo do estudo, ou seja, nÃo tinham apresentado exacerbaÃÃes infecciosas ou hospitalizaÃÃes nos Ãltimos 30 dias. Os grupos foram randomizados para o uso de placebo (N= 10; mÃdia da idade 12,10  6,0) ou melatonina 3,0 mg (N=9; mÃdia da idade 16,62  8,26) durante 21 dias. Um registro actigrÃfico foi realizado durante seis dias, antes do inÃcio da medicaÃÃo e na terceira semana (dias 14 a 20) do tratamento. Os nÃveis de isoprostano e nitrito foram determinados no condensado de ar exalado (CAE) no inÃcio do estudo (dia 0) e depois do tratamento (dia 21). A melatonina melhorou a eficiÃncia do sono (p=0,01) e nitrito do CAE, porÃm nÃo reduziu o isoprostano. Em conclusÃo, em pacientes com FC clinicamente estÃveis, a administraÃÃo de melatonina reduz os nÃveis de nitrito e melhora os parÃmetros de sono.

xiv, 111 p. A print copy of this title is available through the UO Libraries. Search the library catalog for the location and call number.<br>Sleep studies have rarely explored individual differences in sleep disruption and associated outcomes at early ages. In two studies, this dissertation addresses both of these limitations using actigraphy, an activity-derived assessment of sleep, to increase understanding of negative impacts of sleep on early development. Study 1 investigated sleep disruption in foster children and sleep-related treatment outcomes of the Multidimensional Treatment Foster Care for Preschoolers (MTFC-P) intervention program. Study 2 explored individual differences in the associations among sleep, children's behavior, and neurohormonal activity. Four groups of participants ages 3- to 7-years-old were included in both studies: (1) Regular foster care (RFC; n=15); (2) MTFC-P intervention (TFC; n= 17); (3) Low-income community (LIC; n= 18); and 4. Middle-income community (MIC; n=29). Results of Study 1 indicated greater sleep disruption in foster groups, as evidenced by longer sleep latencies and increased variability of sleep duration, in the TFC group than in community groups. There was also indication of a treatment effect as the TFC group slept longer than RFC and LIC groups and had earlier bedtimes, fell asleep earlier, and spent more time in bed than either community group. LIC children had marginally more active sleep than MIC children, indicating a possible role for socioeconomic status in sleep quality. In Study 2, correlational and causal modeling approaches were used to investigate associations among sleep disruption, problem behaviors, and diurnal cortisol. Influences of foster care placement, gender, and age were also examined as potential individual difference factors. Results of mixed linear autoregressive models indicated that children were more likely to display inattentive/hyperactive behaviors after shortened sleep durations. Furthermore, at lower sleep durations, differences among care groups and genders emerged as children in foster care and males were at heightened risk for inattentive/hyperactive behavior problems. No associations between sleep and disruptive problem behaviors were found and there were few associations with morning and evening cortisol values. Results of these studies are discussed in terms of the effectiveness of the MTFC-P program for addressing sleep problems in foster children. Additionally, clinical implications of the heightened likelihood of inattentive/hyperactive behavior problems after disrupted sleep in some children are discussed.<br>Adviser: Phil Fisher

Background: Snoring and obstructive sleep apnea (OSA) are both common disorders with a number of negative health effects. The safety and efficacy of treating snoring and OSA surgically have been questioned and there has been a lack of studies in the field. Aims: 1) To investigate the frequency of serious complications, including death, after surgery for the treatment of snoring and sleep apnea; 2) to evaluate the effect on daytime sleepiness after radiofrequency surgery of the soft palate in snoring men with mild or no OSA; 3) to evaluate the effect of tonsillectomy on sleep apnea in adults with OSA and tonsillar hypertrophy; 4) to investigate the morphology and cytoarchitecture of muscle fibers in human soft palatal muscles with immunohistochemical and morphological techniques. Methods and results: In paper 1, a retrospective database study. All Swedish adults who were treated surgically because of snoring or OSA from January 1997 to December 2005 were identified in the National Patient Register. None of the surgically treated patients died in the peri- and postoperative period. Severe complications were recorded in 37.1 of 1,000 patients treated with uvulopalatopharyngoplasty (UPPP), in 5.6 of 1,000 patients after uvulopalatoplasty (UPP) and in 8.8 of 1,000 patients after nasal surgery. In paper 2, the study was designed as a randomized, controlled trial. 35 snoring men with mild or no OSA were randomized to either radiofrequency or sham surgery of the soft palate. Radiofrequency surgery was not found to be effective since there was no significant difference between the two groups in relation to the Epworth Sleepiness Scale (ESS) or apnea-hypopnea index (AHI) at follow-up. Paper 3 was a prospective study, including 28 patients with an AHI of &gt;10 and with large tonsils. In these patients, tonsillectomy was an effective treatment for OSA; the mean AHI was reduced from 40 units/h to 7 units/h (p&lt;0.001), and the mean ESS was reduced from 10.1 to 6.0 (p&lt;0.001) at the six-month follow-up after surgery. Minor and moderate swallowing dysfunction was found in seven of eight patients investigated before surgery and the swallowing function improved in 5 of them after surgery, while no one deteriorated. In paper 4, we investigated the morphology and cytoarchitecture in normal soft palate muscles. Human limb muscles were used as reference. The findings showed that the soft palate muscle fibers have a cytoskeletal architecture and cellmembrane complex that differs from that of the limb muscles. Conclusions No case of death related to surgery was found among 4,876 patients treated with UPPP, UPP or nasal surgery for snoring or OSA in Sweden between 1997 and 2005. Radiofrequency surgery of the soft palate has no effect on daytime sleepiness, snoring or apnea frequency in snoring men with mild or no OSA. Tonsillectomy can be an effective treatment for OSA in adults with large tonsils. A subgroup of muscle fibers in the human soft palate appears to have special biomechanical properties and their unique cytoarchitecture must be taken into account while assessing function and pathology in oropharyngeal muscles.<br>Snarkning och obstruktiv sömnapné (OSA) är idag en global folksjukdom. Snarkning är det ”oljud” som uppstår när luftvägen under sömn förminskas och vävnaden börjar vibrera under andning. Vid obstruktiv sömnapné faller vävnaden samman och blockerar luftflödet till lungorna. Ett andningsuppehåll, en s.k. apné inträffar. Ett andningsuppehåll kan pågå allt ifrån några sekunder till mer än en minut och kan uppstå hundratals gånger per natt. För att klassificeras som en patologisk apné enligt internationell standard måste andningsuppehållet vara längre än 10 sek. Snarksjukdomen förvärras sannolikt över tid och övergår succesivt i obstruktiv sömnapné med ökande antal andningsuppehåll under sömn. Detta leder till ett stresspåslag för kroppen med oftast uttalad dagtrötthet och en mängd negativa hälsoeffekter. Snarksjukdom och sömnapné ökar risken för bl.a. högt blodtryck och hjärt-kärlsjukdom samt också för att den drabbade ska orsaka trafikolyckor på grund av försämrad koncentrationsförmåga och trötthet. En del av den negativa utvecklingen från snarkning till sömnapné anses bero på att snarkvibrationer kan ge neuromuskulära skador i gom och svalg. Dessa vävnadsskador anses också vara orsaken till att personer som snarkat länge ofta uppvisar störd sväljningsfunktion i form av felsväljning, där maten i uttalade fall hamnar i luftstrupen istället för i matstrupen. I dagsläget är förstahandsbehandling vid sömnapné CPAP, en mask som placeras över näsa och mun och som skapar ett övertryck i luftvägen vilket förhindrar att luftvägen faller samman och att andningsstopp uppstår. CPAP har enligt flera studier den bästa effekten mot andningsuppehåll. En annan vanlig behandling är en bettskena som för underkäken nedåt och framåt så att luftvägen bli mer öppen. Bettskenan är en vanlig och effektiv behandlingsmetod för personer utan kraftig övervikt vid vanemässig snarkning eller måttlig sömnapné. För ett tjugotal år sedan var kirurgi förstahandsmetoden vid behandling av snarkning och måttlig sömnapné. Man utförde då ofta operationer i svalg och gomm, s.k. gomplastiker. Bruket av kirurgisk behandling har dock minskat med tiden, dels p.g.a. biverkningar men också för att det saknades vetenskapliga studier som bevisade att kirurgin gav önskad och långsiktig effekt. Kirurgi utgör dock fortfarande ett komplement till behandling av snarkning och sömnapné när CPAP eller bettskena av olika skäl inte fungerar eller kan tolereras av patienten. 8 Även barn kan lida av snarkning och sömnapné men behandlingsprinciperna för barn skiljer sig från dem hos vuxna och berörs inte i avhandlingen. I denna avhandling studeras: i) biverkningsfrekvenser efter olika typer av snarkkirurgi, ii) effekten av radiovågsbehandling i mjuka gommen på vuxna män med snarkning, iii) effekten av att operera bort halsmandlarna på vuxna med sömnapné och stora halsmandlar, iv) muskelvävnadens struktur och molekylära uppbyggnad i mjuka gommen hos friska personer som inte snarkar. Avhandlingen består av fyra delstudier: 1. En registerstudie med kartläggning av svåra biverkningar efter kirurgi i form av uvulopalatopharyngoplastik, uvulupalatoplastik samt näskirurgi för behandling av sömnapné och snarkning och utfört i Sverige mellan åren 1997-2005. Studien omfattade 4 876 patienter. Inga dödsfall noterades. Komplikationsrisken var störst vid operationer där man tog bort delar av mjuka gommen samt halsmandlarna, där i snitt 37 av 1000 opererade fick biverkningar, framförallt p.g.a. infektioner eller blödningar. 2. I en prospektiv, randomiserad placebostudie utvärderades effekten av radiovågsbehandling i mjuka gommen vid snarkning och lindrig sömnapne. Trettiotvå patienter lottades till att få radiovågsbehandling eller placebo behandling. Patienterna visste inte vilken grupp de tillhörde. Vid uppföljning efter 12 månader var det inga statistiska belägg för att radiovågsbehandling minskade vare sig antal andningsuppehåll eller dagtrötthet. 3. Effekten av att ta bort halsmandlarna på patienter med stora halsmandlar och olika grad av sömnapné utvärderades i denna studie. Totalt deltog 28 patienter. Vid uppföljning 6 månader efter operationen hade antalet andningsuppehåll sjunkit drastiskt, från i snitt 40 till 7 andningsuppehåll per timme nattsömn. Inga allvarliga biverkningar uppstod. Dessa fynd talar för att man som förstahandsmetod ska erbjuda patienter med sömnapné och stora halsmandlar att ta bort halsmandlarna. 4. I detta projekt undersökte vi utseendet och uppbyggnaden av cellskelettet i två normala muskler i mjuka gommen hos friska personer utan känd snarkning och sömnapné. Muskler från armar och ben användes som referens. Fynden i studien visar att de normala muskelfibrernas uppbyggnad i mjuka gomen skiljer sig från jämförade muskler i armar och ben. Detta kan vara ett uttryck för en evolutionär utveckling för att möjligöra de komplexa funktioner som krävs av svalgets muskulatur. 9 Sammanfattningsvis kan vi konstatera: Att inga dödsfall har skett i Sverige efter operationer i gom, svalg eller näsa, utförda för att behandla snarkning och sömnapné under åren 1997 till 2005. Att radiovågsbehandling av mjuka gommen hos snarkande män med lindrig sömnapné inte har någon effekt på dagtrötthet, snarkning eller andningsuppehåll vid uppföljning efter 12 månader. Metoden kan därför inte rekommenderas. Att när man opererar bort stora halsmandlar på personer med andningsuppehåll så leder detta ofta till att andningsuppehållen minskar drastiskt. Metoden kan därför oftast rekommenderas som en förstahandsbehandling för denna patientgrupp. Att mjuka gommens muskelfibrer är uppbyggda på ett unikt sätt indikerar att deras specifika biomekaniska egenskaper skiljer sig från referens muskler i armar och ben.

Researchers have struggled with the problem of obtaining an "accurate" operational definition of drowsiness. Drowsiness is difficult to define because it may involve many different indicators, such as different physiological measures. This thesis consists of two separate, but related, experiments to determine an optimal method of determining whether or not an individual is drowsy via physiological and observed measures. The first part of the experiment used behaviorally trained observers to rate different subjects on the level of drowsiness observed. The data collected showed that trained raters are relatively consistent when rating drowsiness. The second part of the experiment tried to determine if there is a good physiological model to predict performance impairment due to drowsiness by collecting data on sleep deprived subjects. The subjects were given two interleaved tasks, low level and high level cognitive tasks, to perform while twenty-one performance and behavioral measures were collected. The results show that a regression model can be developed using eyelid closure measures, simple EEG measures and simple heart-rate measures to predict performance impairment due to drowsiness.<br>Master of Science