Effect of Moderate Altitude (>1000 m.a.s.l.) on Sleep Examinations (Polysomnography).

Study Overview
=================
Brief Summary
-----------------
The purpose of this study is to investigate the effect of moderate altitude (>1000 m.a.s.l.) on sleep examinations (polysomnography).

Detailed Description
-----------------
Polysomnographies will be done for each participant for 2 consecutive nights at the sleep laboratory in Chur (CH; 600 m.a.s.l.) as well as for 2 consecutive nights at the participants home elevations (CH; >1000 m.a.s.l.). Between the measurements at those two different altitudes there will be a two-week washout period at >1000 m.a.s.l.. The sequence of altitude exposure will be randomized.

Official Title
-----------------
The Different Diagnostic Values of Polysomnographies at Low and at Moderate Altitude - A Randomized Crossover Trial

Conditions
-----------------
Healthy

Intervention / Treatment
-----------------
* Diagnostic Test: Polysomnography


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Healthy (no current medical condition or intake of regular medication, except negligible medical issues or accidents not interfering with the current health status or physical performance.) Living above 1000 m.a.s.l. since at least 1 year No overnight stay at altitudes <1000 m.a.s.l. in the previous 4 weeks 18-70 years old Body mass index 18,5-30 kg/m2 informed consent Exclusion Criteria: Active diseases or health related conditions that require treatment (sleep disorders (mainly sleep apnea), chronic rhinitis, cardiovascular and lung diseases) Use of drugs that affect the respiratory center drive (sedatives, sleep inducing drugs, opioids), stimulants or illegal drugs Regular consumption of recreational drugs (alcohol and nicotine included)

Ages Eligible for Study
-----------------
Minimum Age: 18 Years
Maximum Age: 70 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
Accepts Healthy Volunteers

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Diagnostic
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: A<br>Polysomnographies will be done first for 2 nights at the sleep laboratory in Chur (600 m.a.s.l.) and after a two-week washout period for 2 nights at the participants home elevations (>1000 m.a.s.l.). | Diagnostic Test: Polysomnography<br>* The polysomnographic recordings include electroencephalogram (EEG), electrooculogram (EOG), electromyogram (EMG), electrocardiogram (ECG), pulse oximetry, transcutaneous capnography, nasal airflow and thoracic and abdominal respiratory effort.<br>|
| Experimental: B<br>Polysomnographies will be done first for 2 nights at the participants home elevations (>1000 m.a.s.l.). and after a two-week washout period for 2 nights at sleep laboratory in Chur (600 m.a.s.l.). | Diagnostic Test: Polysomnography<br>* The polysomnographic recordings include electroencephalogram (EEG), electrooculogram (EOG), electromyogram (EMG), electrocardiogram (ECG), pulse oximetry, transcutaneous capnography, nasal airflow and thoracic and abdominal respiratory effort.<br>|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| T90 (time spent in SpO2 below 90%) | T90 is the percent of sleeping time which the participant spent in SpO2 below 90%. It provides information about the duration and degree of hypoxia during the whole sleep. | 4 nights | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| SpO2 (oxygen saturation) | SpO2 is the amount of haemoglobin bound to oxygen. Normal values lie above 95%. Values below 90% are considered as low and require treatment. | 4 nights | 
| AHI (apnea-hypopnea index) | AHI is defined as the number of apneas and hypopneas per hour of sleep, whereby apnea is defined as a cessation of the airflow for ≥10 seconds, while hypopnea is defined as a reduction of the airflow ≥30% with an oxygen desaturation ≥3% or an arousal. | 4 nights | 
| SWS (slow-wave sleep) | SWS includes the deep sleep phase. Deep sleep is amongst other important for energy restoration, immune system strengthening and regeneration of cells. | 4 nights | 
| AI (arousal index) | AI is the number of arousals per hour of sleep, whereby an arousal is an interruption of sleep from 3-15 seconds. They prevent suffocation in the sleep apnea by interrupting breathing pauses but are also coupled with a lot of stress for the human body. | 4 nights | 
| TcCO2 (partial pressure of carbon dioxide) | TcCO2 correlates with PaCO2 and is therefore a non-invasive alternative. A normal value of PCO2 lies between 35 and 45 mmHg. Lower values can lead to muscle cramps, abnormal heartbeat and much more. | 4 nights | 
| WASO (wakefulness after sleep onset) | WASO is the time spent awake after sleep onset. High values of WASO are for example found in sleep apnea, insomnia and restless leg syndrome. | 4 nights | 
| ODI (oxygen desaturation index) | ODI is defined as the number of oxygen decreases ≥3% per hour of sleep. | 4 nights |