Feeling sad is a normal human experience, but feeling too much sadness can cause distress and life problems. When too much sadness affects your life, you might have depression.

Depression is a type of mental health condition called a mood disorder. Mood disorders occur when changes in mood go beyond the normal ups and downs we all experience from day to day. Episodes of depression last at least two weeks at a time, but sometimes they can last for months or even years.

Depression goes way beyond just feeling sad. Some of the symptoms that people with depression experience include:

• Feeling or appearing low, empty inside, or irritable most of the day every day
• Losing interest in activities you would normally enjoy
• Changes in appetite or weight—eating more or less; gaining or losing weight
• Changes in sleep—either not being able to sleep or sleeping too much
• Changes in activity—feeling restless inside or feeling sluggish
• Feeling exhausted even when you seem to be getting enough sleep
• Speaking or moving slowly, fidgeting, or pacing
• Feelings of worthlessness or guilt
• Difficulty thinking, concentrating, or making decisions
• Thoughts of death or suicide

You don’t have to experience all of these to be depressed. Everyone’s experience of depression is slightly different.

What else could it be?

Some things can make it seem like you have depression, when really something else is going on. For example:

• Using drugs or medications that make you feel low. If a medication is making you feel depressed, you should talk to your doctor about it. If you are taking drugs or drinking lots of alcohol, they may be causing symptoms of depression—or you may be trying to self-medicate for depression or another mental illness.
• Medical problems like chronic pain or thyroid problems. Sometimes treating an underlying medical problem can make the depression go away or become less severe.
• Grief. If you’ve lost a loved one or are upset about a big change in your life, you can feel extremely sad for a while. If it doesn’t get better after a long time (more than two months), it can turn into full-blown depression.

Life problems

For people who have depression, the symptoms cause serious problems in their lives. The depression may cause them to withdraw from their family, friends, or partners. They may have a hard time in school or work. They might miss assignments, can’t concentrate on their work, or feel overwhelmed by activities. They may not be able to make it to school or work at all.