Depression is the most common mood disorder in the U.S. and prevalent throughout the world. It is also referred to as major depressive disorder or clinical depression. This extremely debilitating mental illness consists of repeated and ongoing sadness, loss of interest or excitement in activities, decreased appetite and energy, and inability to concentrate. People with depression are sometimes so fatigued that they don’t get out of bed all day yet have a hard time falling asleep at night. Depression can cause insomnia because melatonin, the hormone that regulates sleep, is derived from serotonin, which is depleted in a depressed person’s brain.
As with anxiety, everyone experiences feelings of sadness from time to time. But with depression, bouts of unhappy feelings may happen for no apparent reason. Clinical depression may be diagnosed if symptoms of depression occur without a trigger and are affecting a person’s ability to function every day. The causes of depression remain unknown. Scientists believe it is related to reduced activity of one or more monoamine neurotransmitters, such as serotonin, dopamine and norepinephrine. This is known as the monoamine hypothesis. Current medication-based treatments for depression are based on this hypothesis. Monoamine oxidase inhibitors (MAOIs), tricyclics, and selective serotonin reuptake inhibitors (SSRIs) are commonly prescribed antidepressants. These theoretically work to increase the depleted levels of these neurotransmitters in depressed people. In addition to medications, cognitive behavioural therapy is an effective treatment. In extreme cases, electroconvulsive therapy has been beneficial when no other methods have worked.
