I have heard of this behavior, but I have no direct experience with it. I did find one cat forum post where the moderator had a suggestion of either changing textures or getting a litter pan with higher sides. You should contact your veterinarian and see if their office might have a suggestion for this, and if you find your cat is eating the feces, then contact your veterinarian right away.
Perhaps others who have been through this have a suggestion, but here are my thoughts:
If you've changed litter boxes, locations, or litter type right before the start of this behavior, I would reverse any changes and see if the behavior stops.
If your cat has been stressed by any life changes recently, then try to ease or remove the stress. Give your cat more attention than usual.
You could trying purchasing Feliway, which is synthetic pheromones. This has been known to calm certain cats and reduce stress induced behaviors.
