What is depression?

Many things can trigger depression – poor diet, pain or illness, personal loss, relationship problems, or brain chemistry. Depression can happen around an event, like losing your job or the death of someone close to you. Depression can also come back throughout your life. It is important to know that people do not experience depression in the same way. 


Most people have felt sad, or experienced some of the other symptoms of depression. These feelings can be a normal reaction to loss or a personal struggle. When the sad feelings are intense, last for more than a few days, and interfere with your daily activities, you may have something more than sadness. You may have major depression, which is a treatable medical condition.

Depression can start very slowly, with mild symptoms. You may need professional treatment when more than one of the symptoms happen at the same time, your symptoms last longer than two weeks, and you have problems with doing routine activities. 

People with depression often say they experience:

  • Changes in appetite
  • Sleeping too much, or too little
  • Loss of interest or pleasure with activities they used to enjoy
  • Feeling hopeless

If you or a family member has symptoms, we hope you will use the information here and take steps to manage your depression.  


Major depression is a serious medical illness that affects more than 15 million adults in the United States, or about 1 in 10 adults. Depression is one of the leading causes of disability in the U.S. Women are twice as likely to have depression compared to men, for reasons not fully understood. 

There is no single cause of depression. Some people experience depression during a serious medical illness. Others may have depression with life changes such as a move, or the death of a loved one. Still others have a family history of depression. Whatever the specific cause of depression, scientists have established that major depression is a biological, medical illness and it can be treated.  


Early treatment for depression can make a difference. More than half of people who have one episode of depression will continue to have episodes as often as 1-2 times a year. Treatment can limit how often the symptoms return. Treatment can also help control the symptoms, which can grow stronger and more serious over time. 

Many different treatment choices work well for depression. Treatments can include medication, visits with a therapist, or changes in your daily activities. With proper treatment, up to 90% of people diagnosed with major depression can return to their usual activities and feelings.

Without treatment, depression can lead to long-term suffering, disability or even suicide. 

Learn More: Depression Fact Sheet