What are these rules? The authors of the meta-study point to a paper that tracked pregnant women who planned to breast-feed. Researchers gave some of the women a two-page handout with instructions. One rule on the handout was that parents should not hold, rock, or nurse a baby to sleep in the evenings, in order to help him learn the difference between day and night. Another instruction for week-old babies was that if they cried between midnight and five A.M., parents should reswaddle, pat, re