I've been working in a night shift for more than 2 years .now i always feel tired and weak eventhough i have sleep enough. what should i do?

Shift work syndrome: Night workers often get poor sleep during the day and often have chronic fatigue after a short while doing it. Minimizing light exposure during the day and using medical lamps (used for seasonal affective disorder) can help in setting your physiologic clock - but often nothing works other than switching to a more normal shift.