Sleep Breathing and Oxygen

Understand nighttime breathing, oxygen levels, hypoventilation, respiratory symptoms, and when breathing changes need medical attention.

Oxygen and breathing basics

2guides

Normal Oxygen Levels During Sleep

There is no universal overnight oxygen number. Learn how to interpret SpO2 patterns, device limits, sleep-test results, and warning signs. Updated Jul 2026 → 02

Respiratory Health and Sleep

Understand how respiratory symptoms and sleep interact, how apnea differs from low oxygen or hypoventilation, and when nighttime breathing problems need medical care. Updated Jul 2026 →

Breathing symptoms and conditions

5guides

Hypercapnia

Hypercapnia is elevated arterial carbon dioxide caused by inadequate effective ventilation. Learn how doctors test for it, what can cause it, and when it needs emerg... Updated Jul 2026 → 02

Hypoventilation

Understand inadequate ventilation, sleep-related carbon-dioxide rise, cause-specific testing, respiratory support, and urgent warning signs. Updated Jul 2026 → 03

Orthopnea

Orthopnea is breathlessness that worsens when lying flat and improves upright. Learn how it differs from other nighttime symptoms and when to seek care. Updated Jul 2026 → 04

Paroxysmal Nocturnal Dyspnea

Understand what paroxysmal nocturnal dyspnea means, what can mimic it, how clinicians evaluate it, and when nighttime breathlessness needs urgent care. Updated Jul 2026 → 05

How to Stop Mouth Breathing While Sleeping

Learn why nighttime mouth breathing happens, what you can safely do tonight, why routine mouth taping is risky, and when nasal blockage or sleep apnea symptoms need ... Updated Jul 2026 →