Depression is an emotion that everyone goes through at some point. Under normal circumstances, it goes away in short amount of time. But when it gets so severe that you are unable to function physically and mentally, it is considered major depression. This condition is also known as "major depressive disorder" or "clinical depression," and it comes with various signs and symptoms.
Interest
If you have major depression, regular activities that you once found enjoyable will no longer be interesting to you. This can be things like reading, going to the movies, lifting weights, hanging out with friends or having sex. This lack of interest can last all day long and for weeks at a time.
Sadness
Your mood really gets affected when you have major depression. Feelings of worthlessness, sadness, being "down" and hopelessness can dominate your day-to-day life. You may also experience periods of crying for no obvious reasons.
Anger
When you are really depressed, you can become very irritable and restless. Small, irrelevant things can cause you to become angry as well.
Weight
Your appetite can get affected when you have major depression. Depressed people either eat a lot more or a lot less than they normally do, which can cause excessive weight gain or weight loss.
Sleep
Sleep patterns can be disrupted when you have major depression. You may not be able to get to sleep at all, or you may fall asleep and keep waking up during the night, feeling depressed. This can lead to extreme fatigue during the day. You can also have the opposite happen where you go to sleep and have trouble getting up in the morning.
Mental Ability
Your ability to concentrate--even on the simplest of things--can become compromised when you have major depression. You can also be very indecisive when it comes to making otherwise easy decisions.
Thoughts
When major depression gets to a severe enough point, you may start to display thoughts of suicide and death. In the worst of cases, a plan for suicide might be talked about or actual suicide attempts might be made.
Pain
Major depression symptoms are not limited to emotional pain--physical pain is also a possibility. According to the Mayo Clinic, unexplained physical problems such as backaches and headaches can take place when you are severely depressed.
