Study Looking at End Expiratory Pressure for Altitude Illness Decrease (SLEEP-AID)

Inclusion Criteria:

   - ages 18-65

   - Lake Louise Score (LLS) of < 3

   - Have not taken NSAIDs, acetazolamide, or corticosteroids in the prior week

   - Have not traveled above 4200 m in the prior week.

   - First night in Pheriche or Dingboche

Exclusion Criteria:

   - Unable to read the consent form

   - Taken NSAIDs, acetazolamide, or corticosteroids in the week prior to study enrollment.

   - Hazardous medical conditions which precludes the ability to tolerate the experimental
   device.

   - Pregnancy or suspected pregnancy.

   - Participants who are younger than 18 years of age and more than 65.

   - Travel to or above 4200m in the preceding week.

   - Diagnosis of AMS upon enrollment (LLS ≥3 with symptoms of headache)

   - Previously diagnosed obstructive sleep apnea

   - Current symptoms of nasal congestion, rhinorrhea, sinusitis, upper respiratory
   infection, asthma, COPD exacerbation, pneumonia, bronchitis, or other disease of the
   respiratory tract.