Bed pillows filled with down can clump over time. Here's a simple way to revive your bed pillows while refreshing them, too. Place your pillow in the dryer, and tumble dry it on high for several minutes. The heat will eradicate dust mites and odors that may be lingering inside, and the tumbling action will help redistribute the feathers. After a few minutes, your clumpy pillow will feel, smell and look as good as new.