Why i feel tired all day even if i don't do anything ?

Tiredness.: The most common diagnoses are:viral illness, upper respiratory infection, iron-deficiency anemia, acute bronchitis, adverse effects of a medical agent in the proper dose, and depression or other mental disorder. [12] the most frequent psychiatric illnesses included major depression, panic disorder, and somatization disorder. 33% pts have no cause for tiredness. Go to dr. R/0 anemia.

Many causes: Tiredness/fatigue is one of the most common, nonspecific medical complaints. Often, this can be caused by depression and other mood disorders, poor sleep, caffeine or alcohol use; less common causes include anemia, vitamin deficiencies, even some cancers; sometimes, no specific cause is found. A detailed history and possibly targeted labs can help narrow down the many possibilities.

Many causes: There are many things that could cause this. I suggest going to your doctor for a thorough evaluation.

Tired all the time: Symptoms of fatigue can emerge from so many different problems that it would require medical evaluation. A partial list include, thyroid problems, a sleep disorder esp apnea or narcolepsy, auto-immune disease, anemia. Of course, as a psychiatrist i think of depression, anxiety and bipolar depression. All of these conditions can be treated effectively but need to be evaluated.