Arousal Detection by Using Ultra Short term Heart Rate Variability (HRV) Analysis: 1.Data Acquisition 31 healthy subjects without any any evidence of cardiovascular disease (18 male and 13 female) with a mean of 31.80 years and standard deviation age of 10.80 years were chosen to participate in the experiment. All subjects in this study provided informed consent before participating, and the study was carried out by the Declaration of Helsinki and approved by the local Ethics Commission for Human Experimentation (protocol code CEEAH-5745). 2.Experimental Setup The experimental setup is designed to cause variations in arousal by using the following stages in a laboratory setting to measure the impact of arousal in the human body. 1) Seated Resting: The study does not include this stage, which comprises recording for 2 min to allow for physiological adaption. 2) Non-arousal state (Relaxing Status (R1)): At this level, subjects were advised to breathe on their own but try to maintain a slow breathing rate while listening to nature sounds for 5 min with their eyes closed. 3) Arousal state (Stroop Test (A1)): The Stroop test, which involves presenting subjects with a series of words in various colors, was used to activate arousal. During the test, the subject is listening to traffic jam noise. They are taught to quickly choose the color (either red, blue, green, or yellow) that corresponds to a displayed word on a computer screen while using a mouse with their dominant hand. 5) Arousal state (Stroop Test (A2)): At this level, the Stroop test has been conducted for the second time. However, this stage and stage 3 are simply different in that the subject should choose the color of the rectangle rather than the color of the text. The activity is performed for 5 min. 3.Setup Configuration: The ECG signal in this experiment was recorded by Biopac MP36 acquisition unit with the sampling frequency of 1 kHz. To capture the ECG signal, the standard lead II and consequently, the right arm (RA), left leg (LL), and right leg (RL) have all been attached with three electrodes. By lowering the P and T wave amplitudes and preventing slow drifts related to baseline wander, the high pass, cut-off frequency of 5 Hz conducts a pre-enhancement of the QRS complex at a relatively high value (compared to clinical ECG). On the contrary, interference, and noise are minimized by the low value of the low pass cut-off frequency of 35 Hz. The interval fluctuation between successive QRS complexes is considered to be accurately captured at a sampling frequency of 1 kHz and gain of 1000. 4.Data analysis: After data collection, the RR time series were extracted randomly for each subject in the 30s, 60s, 120s, and 240s time windows. Following, 17 HRV features (all functions are provided here) are computed for each time window with 1000 epochs. Due to the findings, novel indices such as acceleration change index (ACI) [1] and fractional differ-integration index (fnQ) [2] recognize arousal from non-arousal status with an accuracy of nearly 88%. Therefore, ACI and fnQ provided the best performances in arousal detection by using ultra-short-term HRV analysis among all of the obtained indices. References [1] M. A. García-González, J. Ramos-Castro, and M. Fernández-Chimeno, “A new index for the analysis of heart rate variability dynamics: Characterization and application,” Physiol. Meas., vol. 24, no. 4, pp. 819–832, 2003, doi: 10.1088/0967-3334/24/4/301. [2] M. A. García-González, M. Fernández-Chimeno, L. Capdevila, E. Parrado, and J. Ramos-Castro, “An application of fractional differintegration to heart rate variability time series,” Comput. Methods Programs Biomed., vol. 111, no. 1, pp. 33–40, 2013, doi: 10.1016/j.cmpb.2013.02.009.