Aug 13, 2025 · Melatonin is a hormone in your body that plays a role in sleep. The production and release of melatonin in the brain is connected to time of day, increasing when it's dark and …

Jun 20, 2025 · Overview Drug addiction, also called substance use disorder, is a disease that affects a person's brain and behavior and leads to an inability to control the use of a legal or …

Your donation powers the future of medicine and helps save lives.

Feb 20, 2025 · Vitamin C is an essential nutrient, but you can get too much of it. If you're an adult, limit yourself to no more than 2,000 milligrams (mg) of vitamin C a day. The recommended …

Feb 20, 2025 · Vitamin D toxicity is a rare condition that happens when too much vitamin D is in the body. The condition can have serious effects on health. Another name for it is …

Dec 11, 2024 · Wet macular degeneration is an eye condition that causes blurred vision or reduced central vision. It is a type of age-related macular degeneration where blood vessels …

Jul 18, 2025 · Hyponatremia is the term used when your blood sodium is too low. Learn about symptoms, causes and treatment of this potentially dangerous condition.

Feb 1, 2025 · In addition to age, other factors can affect how many hours of sleep you need. For example:

Sep 12, 2024 · Serotonin syndrome is a serious drug reaction. It is caused by medications that build up high levels of serotonin in the body. Serotonin is a chemical that the body produces …

Jan 4, 2023 · Overview Even the best-behaved children can be difficult and challenging at times. But oppositional defiant disorder (ODD) includes a frequent and ongoing pattern of anger, …