====== Snore Study - Why do we snore? ======

===== Dataset - General description =====

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. 

===== Study Protocol =====

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. The data was collected from May - November 2021.

About 60 individuals, both women and men, aged 18-75 were invited to participate. They were split in three groups based on citeria: 
  - Individuals who do not snore or stop breathing
  - Individuals who snore or have mild sleep apnea and
  - 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.

==== Visit 1 ====

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:
  - Ordered List ItemA thorough examination after the airway (~ 20 min).
    - Examination of the nasal cavity.
    - Examination of the oral cavity.
    - 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.
  - Digital photo and audio recording (~ 20 min)
    - Cranio-facial, oropharyngeal (teeth, mouth and throat) images.
    - Video and audio recording of snoring and sounds.

==== Visit 2 ====

The participant arrived at RU and slept there for one night in RU's Sleep Institute Sleep Lab under the supervision of a researcher to see if the equipment is measuring correctly. The participant was asked to arrive freshly bathed, with clean and dry hair. The participant was asked to fill out a short questionnaire on paper, in connection with the sleep study. The next day, the researcher assisted the participant to remove the equipment which concludes the study participation.

The night measurement (setup took ~ 1 hour) included 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.
  * Neck sensors are attached (accelerometer and voice recorder) to detect snoring, see Figure 2.
  * 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 3.
  * A mask is applied, which covers the nose and mouth and measures the total airflow through the airway, see Figure 3.

When the setup procedure was complete, the signals were checked. The researcher asked the participant to perform the same exercises as in visit 1, i.e. to imitate snoring and breathing pauses while they are awake. The participant was then asked to go to bed and sleep until the following morning.

<figure> {{:cluster:datasets:psg.png?200|Figure 1}} <caption> PSG montage </caption></figure>   <figure> {{:cluster:datasets:neck2.png?200|Figure 2}} <caption> Schematic of neck sensors. </caption></figure> 

<figure> {{:cluster:datasets:mask.png?600|Figure 3}} <caption> Schematic of mask and esophageal pressure sensor. </caption></figure> 

===== Summary of the collected data =====

<WRAP half tablewidth>
^ Data source           ^              ^
| PSG                   | 6-channel EEG, 2-channel ECG, thorax and abdominal respiratory movements, nasal air flow, electrodermal activity in palm, audio and video |
| Neck sensors          | Accelerometer and electroglottograph |
| Esophageal pressure sensor |  |
| Airflow mask | The maks separates the nasal and mouth airflow |
| Withings smart watch  | Tracks sleep, pulse plethysmography  |
| Empatica E4 watch     | Electrodermal activity, temperature |
| Voice recording       |            |
| Photographs of oral cavity and teeth |       | 
| Results from ENT consultation |  |
| Questionnaires | ISI, Screening questions for Restless leg syndrome, StopBANG, ESS, Questions about insomnia and sleepiness, Berlin, PSQI, VHI, SNOT22 |

| </WRAP>


===== How to get to know the data? =====


===== How to validate the results data? =====