Serotonin acts as a neurotransmitter, a type of chemical that helps relay signals from one area of the brain to another. Although serotonin is manufactured in the brain, where it performs its primary functions, some 90% of our serotonin supply is found in the digestive tract and in blood platelets.
Chest pain. Obviously, it's very important to get chest pain checked out by an expert right away. It can be a sign of serious heart, stomach, lung or other problems. But depression can contribute to the discomfort associated with chest pain.
Digestive problems. You might feel queasy or nauseated. You might have diarrhea or become chronically constipated.
Exhaustion and fatigue. No matter how much you sleep, you may still feel tired or worn out. Getting out of the bed in the morning may seem very hard, even impossible.
Sleeping problems. Many people with depression can't sleep well anymore. They wake up too early or can't fall asleep when they go to bed. Others sleep much more than normal.
Change in appetite or weight. Some people with depression lose their appetite and lose weight. Others find they crave certain foods -- like carbohydrates -- and weigh more.
Because these symptoms occur with many conditions, many depressed people never get help, because they don't know that their physical symptoms might be caused by depression. A lot of doctors miss the symptoms, too.
These physical symptoms aren't "all in your head." Depression can cause real changes in your body. For instance, it can slow down your digestion, which can result in stomach problems.
Depression seems to be related to dysregulation of nerve cell networks or pathways that connect brain areas that process emotional information. Some of these networks also process information related to how the body senses physical pain. So many experts think that depression can make you feel pain differently than other people. Medicines that treat depression "tweak" the chemicals involved in how these nerve cell networks communicate, making them work more efficiently.