Overnight Study - Why do we snore?

In this Sleep Revolution study the aim was to give a better picture of what is happening in the upper respiratory tract when snoring occurs. The study consisted of two visits, both of which took place at Reykjavik University. For the first visit, participants were asked to be fasting for at least 1 hour before attending. In the second visit, where the installation of equipment before the night study took place, however, liquids were permitted less than 1 hour before the visit.

About 60 individuals, both women and men, aged 18-75 were invited to participate. They were split in three groups based on citeria: 1) Individuals who do not snore or stop breathing , 2) Individuals who snore or have mild sleep apnea and 3) Individuals with moderate to severe sleep apnea. The aim was be to get a good distribution of body mass index, age and gender in all three groups and participants were selected based on that.

The visit begun with an introduction of the study and the participant signed an informed consent. After measureing height, weight, neck circumference, abdominal circumference at navel and blood pressure the following was performed:

1. Ordered List ItemA thorough examination after the airway (~ 20 min).
   1. Examination of the nasal cavity.
   2. Examination of the oral cavity.
   3. Observation with a flexible endoscope, which is slided through the nose and looks down into the throat. The participant is asked to mimic snoring and pauses in breathing while awake, so that it is possible to monitor how the airway responds to these changes.
2. Digital photo and audio recording (~ 20 min)
   1. Cranio-facial, oropharyngeal (teeth, mouth and throat) images.
   2. Video and audio recording of snoring and sounds.

The participant attends RU and stays there one night in RU's Sleep Institute Sleep Lab, researcher will supervise and see if the equipment is measuring correctly. Participant should arrive freshly bathed, with clean and dry hair. The participant also fills out a short questionnaire on paper, in connection with the night study. The next day, the researcher assists the participant in removing the equipment and then the study is compleated.

The night measurement (installation takes ~ 1 hour) includes the following: • Sensors for measuring sleep, breathing, snoring, oxygen saturation, cardio, leg movements, body movements and position are placed on the participant, see Figure 1-A (at the end of this document). • Neck sensors are attached (accelerometer and voice recorder) to detect snoring, see Figure 1-B. • Esophagus pressure sensor is installed. It measures difficulty breathing during sleep. The esophageal pressure sensor is a narrow tube that is inserted through the nose and a almost all the way down into the stomach, see Figure 1-C. • A mask is applied, which covers the nose and mouth and measures the total airflow through the airway, see Figure 1-C.

When the installation is complete, the signals are checked. The researcher asks the participant to perform the same exercises as in the previous visit, ie to imitate snoring and breathing pauses while they are awake. The participant can then go to bed.