Ever feel like your brain is running on empty by 3 p.m.? That mental fog that creeps in during afternoon meetings or when you’re trying to tackle a challenging project might not just be fatigue — it ...

A dangerously low oxygen level—usually below 92%—can cause shortness of breath, confusion, chest pain, or fainting. It’s often triggered by lung or heart conditions like COPD, asthma, or heart ...

Red blood cells transport oxygen throughout your body, including to vital organs and tissues. They also help your body get rid of carbon dioxide. Too little or too many red blood cells may be ...