This latley i started to feel stressed and a bit depressed. i feel sad with no reason and at night is hard to sleep.i feel don't know what to do.

Depression onset: There can be many reasons why depression occurs. Sometimes it's a predisposition in the family history, sometimes it is triggered by a series of negative events, or by prolonged anxiety. If there is nothing medically wrong and If it is affecting your sleep, it is probably good to seek out the assistance of a licensed psychologist who can help identify what's are the core causes and solutions.

Need evaluation: See a mental health professional for evaluation for possible depression. Your primary doctor can refer you. Hard to say what's causing your symptoms with so little information; but life stresses, family history, physical health are important to review carefully. This is also the time of year depression can occur for many as days shorten and exposure to sunlight decreases. I hope this helps.