If you're at all familiar with depression and its causes, you may have heard talk about serotonin. But what exactly is this substance found inside our bodies? It turns out that serotonin juggles multiple roles. It not only plays a part in depression but helps regulate our sleep patterns, appetites, blood-vessel tone, body temperature, secretion of certain hormones, and our perception of pain.

Serotonin is a chemical that works as a nerve-cell transmitter, or neurotransmitter, helping impulses pass from one nerve to the other. It's found not only in the brain but in the blood and the gastrointestinal tract. However, its connection to depression lies in the brain. According to the University of Alabama at Birmingham Health System, scientists believe that people suffering from depression may have imbalances in the brain's neurotransmitters, one of the key ones being serotonin. If serotonin levels are too low, the thinking goes, a person is more likely to fall prey to depression.

For the past two decades or so, depression sufferers have had access to certain antidepressant drugs known as selective serotonin-reuptake inhibitors, or SSRIs. These drugs allow the serotonin present in a person's brain to become more efficient by prolonging the time it's available. They do this by blocking enzymes in the brain that break down serotonin as well as norepinephrine, another neurotransmitter thought to affect mood. But while many depression sufferers are helped by SSRIs, these medicines aren't without side effects. The increased amounts of serotonin available in the brain as a result of taking SSRIs can cause sexual dysfunction, insomnia, nausea, headache, and nervousness.

Uncomfortable with the thought of boosting your serotonin levels with prescription medications? There are more natural remedies you can try. Popular non-drug fixes for low serotonin levels include moderate to vigorous exercise, exposure to sunlight and the outdoors, and eating foods rich in the chemical tryptophan, such as turkey. But if lifestyle changes aren't making your depression lift, talk to your doctor or healthcare provider about trying an SSRI.