Partial sleep deprivation (PSD), is a common problem among current university students in Taiwan. Students often get inadequate sleep time due to burden schoolwork during exam period. In recent years, Issue of sleep quality has gradually been emphasized. According to previous research, lacking in sleep easily results in sleepiness, fatigue, and poor problem-solving performance. Sleep deprivation may also affects cognitive performance, like reducing working memory performance. Furthermore, sleep deprivation will probably alter autonomic nervous function, such as sympathetic/parasympathetic activity change. Previous researches also suggested that sleep deprivation may associated with the risk of being obesity or suffering from diabetes. However, most researches focused on the effects of total sleep deprivation, especially those who usually have night shift work, such as medical staff. Few studies investigated the cognitive function and physiological function of university students after a period of time of partial sleep deprivation. As a results, the aim of the study is to investigate how partial sleep deprivation affects the cognitive performance and physiological function before and after the final exam period in healthy young university students between 20 and 30 years old in Taiwan, in order to promote the importance of healthy sleep and improve sleep quality among university students.

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.

Inclusion Criteria:

• healthy young university students

Exclusion Criteria:

• People who cannot cooperate with the research
• Any medication that may affects the autonomic nervous system(such as beta blockers)
• Pregnancy
• People who have serious musculoskeletal/neurological/cardiopulmonary disorder or other systemic diseases that cannot complete the whole research tasks
• People who have already been diagnosed with any kinds of sleep disorders
• Without sleeping for more than 24 hours

The investigators will recruit 40 healthy young university students between 20 to 30 years old as research participants