# Drowsiness Transitions Detection Using a Wearable Device
## 3 Materials and Methods
### Participants Information  
In order to perform the driving simulations, professors and research fellows, from the Polytechnic Institute of Cavado and Ave, were invited to participate in the experience. Fifty-seven people accepted to be part of this study. Most of the participants were male and, in terms of body mass index, were normal. Follow by overweight, underweight, class II  
Figure 2: Analysis Procedure Flowchart. (\(35\leq bmi<40\)), and class I (\(30\leq bmi<35\)). Moreover, there were participants from different age groups, ranging from 17 to 56 years old. According to the age distribution, Figure 3c, it is possible to identify that most of the participants were young. Furthermore, 50.88% of them played sports, where running, going to the gym, tennis, swimming, and soccer were the most common. There were only 14% of participants that present a health condition, with asthma (37.5%) and hypertension (25%) being the most common followed by type I diabetes (12.5%), myasthenia gravis (12.5%), and Gilbert syndrome (12.5%). In terms of sleep disorders, it was evaluated the risk of developing obstructive sleep apnea, the level of daytime sleepiness, sleep quality, and the circadian rhythm using the Stop-Bang, Epworth Sleepiness Scale, Pittsburgh Sleep Quality, and Morning-Eveningness questionnaires [28; 29; 30; 31]. A few participants presented a high risk of developing obstructive sleep apnea (10.91%), excessive daytime sleepiness (40%), and bad sleep quality (25.45%). Moreover, most of them were neither morning nor evening type (70.91%), followed by morning (16.37%), evening (10.91%), and definitely evening type (1.82%). It was also asked about some substances ingested and the existence of stress, in the 24 h, prior to the simulation. After analyzing the results achieved, Table 1, most of the participants drank coffee, did not ingest medicine, alcohol, or smoked, and did not experience stress. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline  & **Drank** & **Had** & **Drank** & **Smoke** & **Felt Stress** \\  & **Coffee** & **Medicine** & **Alcohol** & **Cigarette** & **Felt Stress** \\ \hline No & 24 & 45 & 5 & 53 & 41 \\ Yes & 33 & 12 & 52 & 4 & 16 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Substances ingested or felt, in the 24 h, before the simulation. Figure 3: Personal information: (**a**) Gender. (**b**) Body mass index. (**c**) Age. (**d**) Type of sports. The next answers were about the participant's experience during the simulation. First, the participants were asked about some symptoms experienced, such as sickness, vision problems, headache, fatigue, itching eyes, concentration problems, and anxiety. They had to rate their intensity from 0 to 5, which corresponds to not at all to very much. Table 2 presents the results achieved. It is perceptible that vision problems, fatigue, itching eyes, and concentration were the symptoms most felt throughout the simulation. Another aspect to take into consideration is the vehicle experience. Thus, it was asked if the participant had any difficulties controlling the vehicle, had any accidents, and had difficulty recognizing potential obstacles and responding to them in a timely manner. In this last question, they had to rate their experience from 0, which represents not at all, to 5, which is very much. A large portion of the participants had no problems controlling the vehicle, although 40.37% did, and 56.14% had an accident. The difficulty in recognizing the obstacles was shown by 66.67% of the participants, although some had more problems than others. The last questions were about the level of drowsiness, considering the Karolinska Sleepiness Scale, in which period of time they felt more drowsy (at the beginning, middle, or at the end of the simulation), if they felt more drowsiness during the night, and the level of difficulty to stay awake (0 representing none up to 5 representing a lot). Note that after the classification of the drowsiness level, the following questions were only presented to those who felt any signs of drowsiness.