目標：本研究旨在了解新冠肺炎大流行前後對青少年身體活動及睡眠的影響。方法：本研究採「準實驗研究」之單一組前後測來進行，並以便利抽樣方式，以台灣台南地區某國中八年級56位學生，於2021年4月～9月，以「智慧手環」及「克里夫蘭青少年嗜睡量表（CASQ）」來蒐集身體活動之每日步數、輕度、中度活動、睡眠時間，及青少年嗜睡情形之數據，並以描述性統計、相依樣本單因子變異數分析國二下學期實體上課、線上上課初期、期末，國二升國三暑假及國三上學期實體上課，共五時期之身體活動及睡眠時間之情形，及「克里夫蘭青少年嗜睡量表（CASQ）」在國二下實體上課、線上上課後，及國三上實體上課，共三時期之變化情形。結果：身體活動不論是每日步數和輕度與中度活動時間都是實體上課較線上上課（初期與期末）和暑假較多。反觀睡眠時間則是於國二下學期實體上課期間為354分鐘最少，線上上課初期為395分鐘，線上上課期末為409分鐘，一直延續到暑假已增加為428分鐘，且到國三上學期實體上課仍持續增加為432分鐘。結論：依研究結果及文獻綜論提出之具體建議如下：一、身體活動方面：實行短時間多回合「低強度身體活動」，如以站立、步行等活動來取代長時間的靜態行為。2.提供線上跨領域雲端課程（家政、童軍、體育、音樂）等學習任務，如完成規定之跑走步數、親子運動活動來養成運動習慣；二、睡眠方面：可於彈性課程中實施睡眠教育，並實施睡眠問卷來了解學生睡眠之實際情形。未來相關單位可利用本研究所提出具體的因應措施及建議，在寒、暑假、或下一波疾病大流行期間，來避免身體活動量不足及改善睡眠問題的情形。

Objectives: This study was conducted to identify the physical activity and sleep patterns of adolescents in southern Taiwan during different phases of the COVID-19 pandemic. Methods: For this study, we adopted a quasi-experimental design with a single-group pretest-posttest approach. Through convenience sampling, we enrolled 56 junior high school (eighth grade) students from Tainan, Taiwan. Data (April to September 2021) on daily steps, low-intensity and moderate-intensity exercise levels, and sleep duration were collected using smart fitness trackers and the Cleveland Adolescent Sleepiness Questionnaire. The students' physical activity levels and sleep durations were measured at five time points: during the second semester of the eighth grade with in-person classes, online classes, and summer vacation and the first semester of the ninth grade with in-person classes. Changes in their Cleveland Adolescent Sleepiness Questionnaire scores were assessed at three time points: during the second semester of the eighth grade with in-person classes, after transitioning to online classes, and during the first semester of the ninth grade with in-person classes. Data were analyzed using descriptive statistics and the repeated measures analysis of variance test. Results: Daily steps, low-intensity exercise levels, and moderate-intensity exercise levels were higher during in-person classes than during online classes and summer vacation. Sleep duration was the shortest during the second semester of the eighth grade (354 min); however, it increased to 395 min at the beginning of online classes, 409 min at the end of online classes, 428 min during summer vacation, and 431 min during the first semester of the ninth grade (in-person classes). Conclusions: On the basis of the findings of this study and a review of the literature, we propose the following recommendations for improving adolescents' health. Physical activity: (1) introduce short, multiple rounds of low-intensity exercises (e.g., standing and walking) to avoid prolonged sedentary behavior and (2) offer online interdisciplinary courses (e.g., home economics, scouting, physical education, and music) as learning tasks, integrating step goals and parent-child activities, to promote exercise habits. Sleep: (1) integrate sleep education into the curriculum and (2) conduct sleep surveys to understand students' sleep patterns. These measures may help address adolescents' inadequate physical activity levels and improve their sleep during school breaks (e.g., holidays and summer vacation) or pandemics.