Influence of Cognition and Physiological Function by Partial Sleep Deprivation

40 healthy young university students who meet the inclusion criteria will be enrolled to the study. The investigators will detailed explain the research process to participants, and make sure all participants provide written informed consent. The study will be conducted in clinical cardiopulmonary function lab in school and graduate institute of physical therapy, college of medicine, National Taiwan University. Baseline evaluation will be conducted after all the midterm exam complete, and make sure there is no sleep deprivation events two weeks before and after baseline evaluation. Outcome measurement will be on the day after all final exams complete. Participants will need to wear ActiGraph GT3X monitor (ActiGraph LLC, Pensacola, FL, USA), which is a non-invasive sleep monitoring device in order to record precise sleep hours and sleep condition, five days before baseline and outcome evaluation. On the days of both baseline and outcome evaluation, the investigators will provide computer device for participants to perform cognitive performance test, which will take around 15 minutes to complete. Next, participants can take a rest for 10 minutes on the bed in supine position before heart rate variability measurement starts. The investigators will place electrode on participant's right forearm, then the non-invasive device will record heart rate variability data for about 5 to 10 minutes. At last, the investigators will evaluate participant's dominant hand grasp strength (kg) by Jamar hand dynamometer (Jackson, MI, USA) devices in standing position.