You used to enjoy reading, now you no longer do. There is now almost nothing that gives you pleasure and the sense of happiness. You are almost always in a low mood and constantly worried about something. You have very low self esteem. These are signs of depression. Depression can be a serious mental illness. This condition causes disturbance in your daily life and when it becomes severe; it would disrupt and destroy your life.

Depression occurs when the chemical serotonin decreases in the brain. Serotonin regulates emotion, body temperature, hormone levels, sleep pattern as well as blood pressure. When serotonin levels are low the brain cannot function optimally.

The following are the common clinical signs of depression (symptoms include):

- Generally in a low mood and can find no pleasure in any activities. What used to be enjoyable no longer gives joy. This could be in any aspect of your life and often in almost all areas of your life.

- Easily irritable and annoyed. You get easily ticked off and sometimes at no apparent reason. Even attempts at making yourself happy annoy you.

- Feeling of worthlessness, guilt and even self-hatred. You keep on being worried about everything. Small issues seems big to you. When things go wrong, you blame yourself, you feel guilty of everything.

- Insomnia. This is a vicious cycle. The more you try to sleep, the more disturbed you become and sleep avoid you. Lack of sleep makes you even more irritable. You would also feel lethargic all the time, with a monster headache to boot. When everyone is asleep at nite, the feeling of loneliness would give way to feelings of hopelessness and despair.

clinical signs depression- Poor concentration and memory. The lack of sleep and irritability will cause you to have poor concentration and poor memory. You would tend to forget things, even routine stuff.

- Feeling of restlessness. Without knowing exactly why, you constantly worry about nothing in particular.

- You become socially withdrawn. And this would compound the feelings of worthlessness and loneliness.

- Reduced libido.

- Thoughts of death or suicide. This would occur when you keep feeling worthless, hopeless, lonely and guilty.

- Lethargic. With lack of sleep, you would feel tired all the time.

- Loss of appetite and/or unexplained weight loss.

- In severe cases, psychosis is induced which include delusion or even hallucination. This marks that the depression is getting severely serious.

- Unexplained health complaints like backache, palpitations and rise in blood pressure. Sever and prolonged stress on your being would cause the body to not operate s it should.

- Emotionally over sensitive. With thoughts of worthlessness and guilt, you would feel sensitive to any comments or happenings.

These symptoms can be of varying degrees in different people because everyone experience depression in different ways. It depends on the age factor, social standing and family structure amongst others. For instance, teenagers would have different symptoms of depression than a 60 year old.

A single person experiences it differently than a person who has a strong family background. The common thing is that they all feel miserable without actually knowing exactly why.