Default [Q] undesirable screen lighting

I am suffering from undesirable screen lighting ie the screen is from time to time on although phone is idle . at day-light it is not recognized but in darkness it is annoying. although this problem is marked as a similar threads after revising I could not find a define answer . my phone is, Samsung Galaxy Core . my available solution right-now is to shut-down the phone could someone give help to end this non-pleasing issue

thanks in advance