The pineal gland is a very small gland in your brain and it is part of the body's endocrine system.
The hormonal system influences your metabolism, growth and many other functions. Learn more about what it is and conditions related to the hormonal system.
Endocrine glands and their hormones
The hormone system is the way in which one part of the body tells another part of the body to do something important. Find out more about different parts of the hormonal system.
Melatonin is a hormone produced in the brain. It controls the body’s night and day cycles. Learn more here, including how melatonin levels can be adjusted.
Bipolar disorder is a mental-health condition in which people experience periods of depression and mania. Learn about its symptoms and treatment.