Everyone experiences moments or days when they feel sad, stressed or irritable, which is normal. However, some people feel those things most of the time and don't feel happy very often. Those people probably also have issues eating and sleeping, trouble concentrating and feelings of hopelessness and worthlessness. They might be fatigued on a regular basis and have thoughts of death and suicide. The people who struggle with those issues suffer from depression.
Hopelessness and Worthlessness
When someone who isn't depressed hits a rough patch and experiences stress, she understands that it will get better in the future. If you're depressed, you probably see no hope for the future. For instance, you might hate your job but not take any steps to change it. You don't see the point, because you feel as if sending out your resume, going on job interviews and scouring the Internet for job openings will result in zero positive changes.
You probably also experience feelings of worthlessness. People who struggle with depression don't focus on the positive things that they do. Instead, they focus on the negative. An adolescent who's depressed won't get excited when she gets a good grade on her English paper. Instead, she'll get upset when she gets a couple questions wrong on her science test. Even though her English paper proves that she's capable of getting good grades, she'll focus on what she's done wrong and think she's stupid and inadequate.
School and Work Issues
The symptoms of depression cause the people who suffer from it to have a decline in their work and school performances, according to Helpguide.org. If you're depressed, you might not be able to even get out of bed every day to go to work. You might call in sick or just not show up. When you do show up for work, you're exhausted and can't concentrate. You might have trouble meeting deadlines, difficulty paying attention during staff meetings and fall behind on your duties. This can lead to a demotion or being fired.
A big sign with children and adolescents that something isn't quite right is issues at school. A depressed child might go from getting mostly A's to getting mostly C's. His performance may not slip to failure, but it will slip. He might get into arguments and fights with his peers and teachers, skip school or deliberately misbehave.
Isolation and Relationships
Often, friends and family members will pick up on signs that their loved one is depressed. They may not recognize it as depression, but they'll notice a shift in the person's mood and behavior. If you're depressed, you might isolate yourself from your friends and family members. You might work late to avoid family dinners, turn your cell phone on silent to avoid your friends' phone calls and snap at your family members when they try to help you or ask if anything is wrong.