Many times pillow fights occur during children's sleepovers. Since pillows are usually soft, injuries rarely occur. The heft of a pillow can still knock a young person off balance, especially on a soft surface such as a bed, which is a common venue. In earlier eras, pillows would often break, shedding feathers throughout a room. Modern pillows tend to be stronger and are often filled with a solid block of artificial filling, so breakage occurs far less frequently.