the_title(); inside a loop/echo

just trying to apply the_title(); within my litebox rel. worked before I used it in a loop. im not a php buff.

<?php
	for($i=1; $i<6; $i++){               //loop 5 times
	  if(get_field('image_' . $i)){       //check if there is an image on each iteration of the loop
	echo' <a href="' . get_field('image_' . $i) . '" rel="lightbox[ the_title();]"><img src="' . get_field('image_' . $i) . '"/>';  //output results
					}
				}
				?>