Most people are oxygen deprived and so they are energy deprived.
Symptoms include -
Chronic or intermittent fatigue
Anxiety and panic attacks
Tingling and numbness in arms and legs
Chest pains and palpitations
Muscular cramps in neck, shoulders and back
Stomach upsets, heartburn and gas
Feelings of unreality, feeling apart, hallucinations
Sleep disturbances, nightmares and night sweats
Where are you breathing from?