A61 SLEEP, Volume 42, Abstract Supplement, 2019 A. Basic and Translational Sleep Science IX. Sleep and Circadian Interactions PSG parameters and PVT indices did not show signifcant differ- ence between each light condition. Conclusion: This study shows that OLED have less effect on mela- tonin suppression then LED light during evening and early night time, and it may suggest OLED is suitable for bedroom light to facilitate sleep. Further investigation using various intensity and color temperature of light.is needed to elaborate effect of OLED light on sleep and circadian rhythm. Support (If Any): None. 0148 DIFFERENCES IN SLEEP DURATION AND QUALITY BETWEEN WEEKDAYS AND WEEKENDS IN JAPANESE ADULTS Seiko Miyata 1 , Kunihiro Iwamoto 1 , Motoo Ando 2 , Yuki Ito 2 , Aiko Noda 3 , Norio Ozaki 1 1 Department of Psychiatry, Nagoya University Graduate School of Medicine, Nagoya, Japan, 2 Nagoya University Hospital, Nagoya, Japan, 3 Department of Biomedical Sciences, Chubu University Graduate School of Life and Health Sciences, Kasugai, Japan. Introduction: Chronic, lifestyle-driven sleep restriction is common in many modern 24-hour societies. In these instances, people will compensate for their weekday sleep deprivation by sleeping more on weekends. Many cohort studies revealed that weekend sleep ex- tension compensates for short weekday sleep in relation to mor- tality, obesity, and hypertension. However, these studies used self-reported sleep durations, and did not focus on objective sleep quality. The aim of this study is to evaluate differences in sleep dur- ation and quality between weekdays and weekends using a portable EEG monitoring device. Methods: Twenty-onetwo Japanese volunteers, aged 20-67 years (4 female and 17 male), enrolled in this study. They underwent seven days of monitoring using a portable EEG device that recorded their sleep activity. These recordings were used to evaluate sleep parameters, such as total sleep time (TST), sleep effciency [% of time in bed (TIB)], sleep latency, wake time (% TIB), wake after sleep onset (WASO), REM sleep, light sleep (stages N1 and N2), and deep sleep (stage N3). Results: TIBs on Friday and Saturday night were signifcantly longer than other nights of the week, leading to longer TST on Friday and Saturday night. Sleep effciency (% TIB) was better on weekdays than weekends, and wake time (% TIB) was greater on Friday, Saturday and Sunday nights as compared to other days of the week. WASO and light sleep were longer on weekend nights than weekday nights, meanwhile, REM sleep and deep sleep were unaffected by the day of the week. Conclusion: TIB and TST increased on weekend nights, but sleep effciency tended to decrease. REM sleep and deep sleep were stable throughout the week, while light sleep increased as TST was longer. Extended TIB may increase WASO and light sleep. Support (If Any): Collaboration study with The KAITEKI Institute, Inc. 0149 STRESS, SLEEP, AND CIRCADIAN ACTIVITY RHYTHMS AMONG COLLEGE STUDENTS: A PRELIMINARY REPORT Xiaoyu Zhang 1 , Yang Hu 2 , Tara Bridgeman 2 , Shih Feng Chou, PhD 2 , Neil X Dong, PhD 2 , Shih Yu Lee 3 1 University of Texas at Tyler, University of Texas at Tyler, TX, USA, 2 University of Texas at Tyler, Tyler, TX, USA, 3 University of Texas at Tyler, Alpharetta, GA, USA. Introduction: Circadian rhythms play an important role in regulat- ing sleep. Sleep disturbances are prevalent in college students and could be resulted from stress, which further desynchronized circa- dian rhythms. This preliminary report aimed to describe the char- acters of sleep and circadian activity rhythm (CAR) and examine the associations of stress, sleep, and fatigue severity in college students. Methods: Impaired sleep model was used to guide for this on-go- ing two-phases descriptive correlational study. Three sets of questionnaires were used during (week I) and after (week II) the midterm exam to assess their stress, sleep, and fatigue. 14-days con- secutive wrist actigraphy data, including total sleep time (TST) and wake after sleep onset (WASO) were collected. Cosiner analysis was used for computing the CAR, including amplitude, mesor, and acrophase. Results: A total of 14 (5 males, 9 females) college students partic- ipated this study, with a mean age of 23.43 (SD=3.98). During the exam week (week I), students perceived moderate stress (M=15.1, SD= 8.2) and reported about 2-3 nights of sleep disturbances. In average they need 459 minutes of sleep to feel refreshed; however, they only slept 426.2 (SD=59.5) and 433.2 (SD=50.6) min/day in week I and II, respectively. The average TST was less during week- days than weekend. The WASO were > 10% for both weeks indi- cating fragmented sleep, and CARs were 0.74 (SEM=0.04) and 0.77 (SEM=0.04) for week I and II, respectively. The acrophase was around 4 pm indicating an evening-typed person. During the exam week, stress level was positively associated with sleep distur- bances, poor daytime functioning, and poor activity correlation; self-reported sleep disturbance was associated with more WASO and higher morning fatigue level; better CAR was associated with better TST (all p< .02). Conclusion: In this preliminary report, fndings revealed college students experienced stress, fragmented sleep, fatigue, and desyn- chronized CAR. Stress coping strategies and sleep hygiene should be mandatorily included in the college education. Support (If Any): This project was funded to S.F. Chou by a Presidential Interdisciplinary Grant at the University of Texas at Tyler. 0150 EXPLORING ASSOCIATIONS BETWEEN SLEEP SPINDLE CHARACTERISTICS AND CIRCADIAN PREFERENCE IN ADULTS Katrina Rodheim, Ahren Fitzroy, Bethany Jones, Jen Holmes, Sanna Lokhandwala, Rebecca Spencer University of Massachusetts Amherst, Amherst, MA, USA. Introduction: Decreased spindle amplitude and intensity has been found to be related with circadian preference for morningness in adolescents. However, it is unknown whether this is the case in adults. Thus, this analysis aims to look at the relationship between adult Horne-Ostberg Morningness-Eveningness Questionnaire (MEQ) scores and polysomnography data to determine whether the same is true in adult populations. Methods: Participants (N=15, M=41.07 years) completed the MEQ to determine their personal circadian preference. Polysomnography was recorded in participants’ homes using the Aura PSG ambulatory system (Grass Technologies) during Downloaded from https://academic.oup.com/sleep/article/42/Supplement_1/A61/5451433 by guest on 24 March 2023