On summer i sleep at 4-5 am and wake up at 3-4pm and eating lunch at this time my father say its bad to ur health and my cause disease ! is it bad ?

Yes: The first question is why are you up until 4-5 am, because whatever you are doing until 4-5 am may be detrimental to your health (unless you are working or doing something productive). This will also effect your circadian rhythms and will make it difficult to get back into normal routine. Always a good idea to get into the habit of having a regular bedtime and sticking to it all of the days