Materials and methods: A sample of 1669 students (age average of 15.5 years, 47.2% male sex) was studied. A form was applied which included symptoms of sleep disorders, sleeping habits and the Epworth sleepiness scale; applied as part of the UNAM Automated Medical Survey. The data was analyzed with the SPSS version 16. Results: We identified that 20% rated their sleep quality as  5/10, 31.2% sleep less than 6 hours, 28% obtained a subjective sleep efficiency of less than 85%, 27.3% obtained  7 points on the Epworth Scale, 26.9% had insomnia onset, 24% reported tiredness, 58.7% difficulty getting up, 8.7% snoring and 6.9% nightmares, 62.1% use the cell phone in bed, 24.3% do homework in bed and 17.6% sleep with pets in bed. Conclusions: A high prevalence of insufficient sleep syndrome and of nocturnal and daytime symptoms associated with sleep disorders was identified, also, dysfunctional sleeping habits. Therefore, it is urgent to design intervention strategies to improve the quality of sleep in high school students. Acknowledgements: The entire team of the sleep disorders clinic and the General Directorate of Health Care of the National Autonomous University of Mexico. Sleep Breathing Disorders EVALUATION OF THE EFFECT OF THE MANDIBULAR ADVANCE DEVICE IN THE UPPER AIRWAY USING MRI R. Gutierrez Vargas 1, 2 , E.P. García Campos 1 , R. Guti errez 1 , M. Miranda Casarrubia 1 , M. Ruiz Morales 2 , U. Jim enez Correa 1 , A. Mor on Mendoza 3 , J. Azpiroz-Leehan 3 , S. Hidalgo Tobon 4 , R. Santana Miranda 1 . 1 Sleep disorders clinic, National Autonomous University of Mexico, Mexico; 2 Otolaryngology, Institute of Social Security and Services of State Workers. National Medical Center November 20, Mexico; 3 National Center for Imaging and Medical Instrumentation, Mexico; 4 Imaging, Federico G omez Children's Hospital of Mexico, Mexico City, Mexico Introduction: Currently, mainstream therapies for Obstructive Sleep Ap- nea Symdrome (OSAS) include weight loss in obese patients, conservative treatment using continuous positive airway pressure (CPAP) and Mandibular Advancement Devices (MAD). The use of MAD has proven to be useful in reducing the Apnea Hypopnea Index (AHI) and symptom- atology in patients with Obstructive Sleep Apnea. Because the upper airway extends from the nose to the larynx, its relationship with the MAD is complex and the changes that occur with its application can occur at anatomical or physiological levels. Materials and methods: Fourteen subjects who had polysomnographic diagnosis of Obstructive Sleep Apnea Syndrome associated with a tongue base obstructive were taken. A personalized MAD was made for each pa- tient and MRI was performed with and without the MAD in awakened patients in dorsal position. Three anteroposterior measures (retropalatine, retrolingual and retroepiglottic) were taken evaluating their differences in a sagittal cut in the midline. MRI study was performed in a 3 Tesla device, Philips, Achieva, using a 3D Fast Field Echo pulse sequence weighted at T1, SENSE, with a 256x256 matrix, TR ¼ 15ms TE ¼ 2.303ms. The measure- ments were made in a cutting thickness of 2mm, NSA ¼ 2 and using the OSIRIX MD software. Results: It was found that, of the 14 patients, the space that was enlarged in more patients was the retroepiglottic space (N ¼ 9), followed by the retropalatinal space (N ¼ 5) and the retrolingual space (N ¼ 4). However, when performing the statistical analysis, there was no significant differ- ence (p> 0.05) in any of the 3 spaces with respect to measurements with and without the application of MAD. However, a significant change was found in the volumetric measurements made at the level of the upper airway studied, a two-tailed T-student statistic with a value of 0.4266 was applied. Conclusions: It is believed that the effect of MAD on OSAS is due to the increase in the upper airway space. However, in our study there are no significant increases in the spaces, so this improvement could be caused not only by anteroposterior increments of the upper airway, but by a volumetric effect as shown by the magnetic resonance imaging. We consider the need to increase the sample of patients and in sleeping conditions monitored during the acquisition of MRI in future research Acknowledgements: The entire team of the sleep disorders clinic of the National Autonomous University of Mexico, the National Center for Imaging and Medical Instrumentation and the Imaging Department of the Federico G omez Children  s Hospital of Mexico. Sleep Breathing Disorders OBSTRUCTIVE SLEEP APNEA AND ITS INFLUENCE ON INTRACRANIAL ANEURYSM H. Jin , T.Y. Jung, H.Y. Kim. Department of Otorhinolaryngology-Head and Neck Surgery, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Republic of Korea Introduction: Obstructive sleep apnea (OSAS) is a well-known risk factor for cardiovascular morbidity and frequently causes vascular instability and inflammation during sleep. So, we tried to investigate the relationship between OSAS and the development of intracranial aneurysm (IA). Materials and methods: We enrolled 564 patients who visited health promotion center and undertook polysomnography and screening brain Magnetic Resonance Angiography (MRA). The prevalence and size of IA were investigated about the association with OSAS and the possible risk factors. Results: The mean age 55.6±8.5 years and 82.3 % were male. The preva- lence of IA was 10.5% and significantly higher in the patients with OSAS (P¼0.02) or family history of cerebrovascular disease (P¼0.03). After adjusting all possible confounding factors for IA and OSAS, presence of OSAS were still significantly associated with the presence of IA. Further- more, OSAS group had significantly larger aneurysm size compared with the non OSAS group (P¼0.013). Conclusions: We found suggestive association between OSAS and intra- cranial aneurysm. Insomnia OBJECTIVE AND SUBJECTIVE SLEEP PROBLEMS AND QUALITY OF LIFE OF REHABILITATION IN-PATIENTS WITH MILD TO MODERATE STROKE K.-L. Joa 1 , Y.-H. Yoo 1 , S.-G. Kang 2 , W.-H. Kim 2 . 1 Department of Physical Medicine and Rehabilitation, Republic of Korea; 2 Department of Psychiatry, Inha University, Incheon, Republic of Korea Introduction: The principal objectives of this study were to investigate relationships between objective sleep parameters that is, sleep onset la- tency, wake after sleep onset, number of awakenings, sleep efficiency, and sleep duration, and the quality of life after mild to moderate stroke. Materials and methods: The subjects were 112 first-time mild to mod- erate stroke patients admitted to a rehabilitation unit. At about 20 days after stroke, physical functions, depression, anxiety, quality of life, sub- jective insomnia, quality of sleep, and fatigue were assessed. Objective sleep parameters were also assessed using wrist worn actiwatch. Results: Patients with insomnia had greater sleep onset latency (p¼0.001), wake after sleep onset (p¼0.005), awoke more frequently (p¼0.013), and slept less efficiency (p< 0.001) than patients without insomnia, but total sleep durations were similar. In all participants, lower overall domain of quality of life was significantly associated with sleep onset latency (p¼0.009), and total insomnia severity index (p< 0.001), total Epworth Sleepiness Scale (p< 0.001), the National Institute's Health Stroke Scale (p¼0.004), Modified Barthel Index (p¼0.034), and Screening Tests for Aphasia and Neurologic-Communication Disorders (p¼0.044) scores. Conclusions: Objective sleep parameters (sleep onset latency and sleep efficiency) were found to be associated with quality of life during the early stage of rehabilitation in mild to moderate stroke patients. Other ASSOCIATIONS OF PSYCHOSOCIAL FACTORS, SHORT SLEEP, INSOMNIA, AND FRAGMENTATION AMONG AFRICAN-AMERICANS, THE JACKSON HEART SLEEP STUDY D. Johnson 1, 2 , N. Guo 3 , T. Lewis 4 , T. Sofer 3, 5 , D. Williams 6 , M. Sims 7 , J. Wilson 7 , S. Redline 3, 5 . 1 Epidemiology, Emory University, Atlanta, United States; 2 Brigham and Women's Hospital, United States; 3 Sleep and Circadian Disorders, Brigham and Women's Hospital, Boston, United States; 4 Epidemiology, Emory Univeristy, Atlanta, United States; 5 Harvard Medical School, United States; 6 Social and Behavioral Sciences, Harvard University, Abstracts / Sleep Medicine 64 (2019) S1eS359 S178