I feel depressed all the time.i am unable to concentrate on my studies.i am haunted by the past, exhausted by the present and terrified of the future.

See you are in: Behavioral therapy. Cognitive behavioral therapy can be especially helpful. Have you been evaluated to see if psychotropic medications are indicated ? What else are you doing to take care of yourself. Don't isolate. Spend time w people. Use your support system. Get out. Don’t stagnate at home. Get at least 8 hours of sleep per night ; eat healthfully. Daily aerobic physical activity is a big +.

Psychiatric help: Your symptoms sound like, what are referred to as "vegetative" signs of major depression. However, you need to see a qualified psychiatrist for accurate diagnosis and treatment. The general result is that with proper treatment you should find relief.