Depression

I suspect that I am suffering from depression. So I went to research about it on Wikipedia.

Clinical depression can present with a variety of symptoms, however almost all patients display a marked change in mood, a deep feeling of sadness, and a noticeable loss of interest or pleasure in favorite activities. Other symptoms include:

Persistent sad, anxious or "empty" mood
Loss of appetite and/or weight loss or conversely overeating and weight gain
Insomnia, early-morning awakening, or oversleeping
Restlessness or irritability
Feelings of worthlessness, inappropriate guilt, helplessness
Feelings of hopelessness, pessimism
Difficulty thinking, concentrating, remembering or making decisions
Thoughts of death or suicide or attempts at suicide
Loss of interest or pleasure in hobbies and activities that were once enjoyed
Decreased energy, fatigue, feeling "slowed down" or sluggish
Persistent physical symptoms that do not respond to treatment, such as headaches, digestive disorders, and chronic pain

Bolded are what I am experiencing right now.

But then again, will people suffering from depression know that they are suffering from depression?