Nearly everyone has dealt with a life-changing event that brings about feelings of sadness. But some people struggle to enjoy normally happy situations. When these feelings do not go away on their own, they may indicate the presence of depression.

Major depression is one of the world’s most common mental disorders. The World Health Organization offers that major depression also carries the heaviest burden of disability among mental and behavioral disorders. People often do not realize they’re suffering from a depressive episode, and as a result, many never seek or receive the care they need. According to “The Diagnostic and Statistical Manual of Mental Disorders,” major depression is characterized by depressed mood, loss of interest or pleasure and at least four others symptoms. These may include problems with self-image, sleep, energy, ability to function, and changes in appetite. The National Institute of Mental Health says that, as of 2013, an estimated 15.7 million adults aged 18 or older in the United States had at least one major depressive episode in the past year. Depression is far-reaching and more common than one may imagine.

Often times, however, people delay seeking treatment because of embarrassment or the stigma that surrounds a mental illness diagnosis. The NIMH indicates that women are 70 percent more likely than men to experience depression during the course of their lifetimes, largely due to hormones. Elevated rates of depression among women also may be due to the fact that they tend to be more vocal and proactive in seeking help. According to Gail Lovallo, LCSW, owner of Peaceful Living Counseling Services, LLC, depression can be linked to any number of factors. Depression may result from a particularly traumatic episode in one’s life and often accompanies post-traumatic stress disorder. Individuals can become depressed when diagnosed with a disease. Women may experience post-partum depression after childbirth.

A considerable percentage of people experience depression when seasons change, and that could be caused by the reduction of exposure to natural sunlight when fall gives way to winter. Seasonal affective disorder, or SAD, is often more common the farther north one lives. Depression can affect one’s home and worklife. In the journal Depression and Anxiety, a study analyzed depression statistics from the Canadian National Population Health Survey and found that major depression doubled a person’s chance of becoming divorced or separated. Others may face job loss thanks to lack of productivity or missed days.

While depression is common, it also is highly treatable.Various therapies exist to mitigate symptoms and restore people to more well-rounded lifestyles. Counseling and medication are two of the more common treatments for depression. According to Psych Central, the Internet’s largest and oldest independent mental health social network, 60 to 70 percent of depressed patients who are given an antidepressant recover from their depression in three to six weeks, provided that the medication dosage is correct and the patient continues to take the medicine as directed. Depression can be a devastating illness that seemingly comes out of the blue.

However, it’s important for people to realize that depression is common and treatment methods are quite effective. Consult with a primary care doctor or a mental health professional if you believe you are experiencing depression.