Alcohol or drug abuse

Chronic or short-term congestion of the nose and sinuses

Diabetes, type 1 or type 2, that is treated with insulin (usually)

Drugs that can cause drowsiness

Fainting spells

Gastroesophageal reflux if severe

Habitual air swallowing

Heart disorders, such as coronary artery disease, heart failure, irregular heart rhythms, valve disorders, and congenital heart defects that allow blood to leak from the venous to the arterial system such as atrial septal defects

Inguinal hernia that has not been repaired

Impulsive behavior or being prone to accidents

Lung problems*, such as asthma, lung cysts, COPD/emphysema, or previous pneumothorax (collapsed lung)

Obesity†

Older age†

Panic disorder

Physical disabilities

Poor cardiovascular fitness

Pregnancy

Ruptured eardrum

Seizures