If it is difficult for you to open your underbed drawers, then you may be becoming frustrated, or even decide that you don't want to use the drawers any more. Rather than giving up and allowing the drawers to stick, you should try to repair the drawer before it is too late.
Step 1 - Check the Drawer
Pull out your sticking underbed drawer, and examine the angle of the bed. If it has fallen off-center, or become crooked, then this could cause the drawer to jam. You may also find that swapping the sticking drawer with another one of your underbed drawers can help to solve the problem. If that doesn't work, then you should check the bed of the drawer for problems such as sticking-out nails, insect shells, or dust.
Step 2 - Clean and Lubricate
Another solution is to try cleaning and then lubricating the underbed drawers. Wipe around the sides of the drawer, and the sliding panels in the bed, and then add a little lubrication. Move the drawer backwards and forwards several times in order to allow the lubrication to reach all sides of the underbed drawers. You should then have solved the problem.