It's important to note that most studies on bed sharing have looked only at the generic category of SIDS deaths, which includes all babies who suddenly and unexpectedly died of unknown causes. Many of those might have been suffocated or overheated—among the two most likely causes of bed-sharing deaths—but others could have died for unrelated reasons. (Five to 10 percent of SIDS cases occur without any apparent risk factors—the baby is found lying on his or her back without pillows or bedding, having simply stopped breathing.) But more specific data may soon be on the way. In 1996, the U.S. Centers for Disease Control and Prevention released a protocol for infant death scene investigation, with the goal of better understanding the factors and circumstances involved in unexpected infant deaths. Since then, bed-sharing-associated infant deaths specifically attributed to suffocation have quadrupled, and bed-sharing deaths more generally characterized as SIDS have correspondingly dropped. Some reports (including an article published in Slate in 2009) have highlighted growing infant suffocation rates as possible evidence that bed-sharing deaths are increasing, but the spike may simply be an artifact of the new labeling scheme.
So should parents bed share or not? From a public health perspective, the answer is a clear no—in general, babies are more likely to die when their parents sleep next to them. The American Academy of Pediatrics’ website for parents, healthychildren.org, recommends that babies “should sleep in the same room as the parents, but not in the same bed.” But if parents don’t smoke, drink, or use drugs, and if they sleep in a bed with a hard mattress and keep pillows, covers, and other kids away from their infants? Some studies do suggest some benefits. Mothers seem to awaken and nurse more frequently when they are sleeping with their babies rather than separately, and skin-to-skin contact between mother and baby has been shown to improve health outcomes, particularly in preterm infants. But it’s impossible to say for sure whether this practice is 100 percent safe. There are lots of potentially confounding variables at play, and scientists have never conducted a randomized, controlled study to find the answer. (Researchers who believe that bed sharing is intrinsically dangerous never would, for ethical reasons.)
Nevertheless, some doctors and parents find the American Academy of Pediatrics’ anti-bed-sharing recommendations unrealistic. Even if parents don’t intend to bed share, many inevitably do—particularly exhausted moms who bring their babies into their beds to nurse multiple times a night. (I accidentally fell asleep multiple times while nursing my 10-month-old boy, only to wake up in a panic and check that he was breathing. And I can’t help but wonder whether Bialik’s decision to bed share was also in part driven by convenience: Her eldest son woke up every couple of hours until he was 2 years old, she writes, and it’s far easier to tend to a crying baby when he’s next to you.) Other people bed share because they can’t afford cribs—bed sharing is more common among low-income families—and there are undoubtedly plenty of moms who sleep next to their kids because they are convinced that it helps them wake up when their infants need them, facilitates nursing, and helps to regulate their babies’ body temperatures.
Of course, any such benefits would be outweighed by the risks when bed sharing isn’t done safely. It’s surprising that Bialik—who prominently displays the Ph.D. next to her name on the book cover—fails to discuss these do’s and don’ts with her readers in her sleep chapter. A box separate from the main text notes that “you should co-sleep with your child only if you understand and adhere to the guidelines for safe co-sleeping,” and the Resources section at the back of the book mentions several books, articles, and products related to the practice, but considering that Bialik is encouraging her readers to sleep next to their babies, she should also spell out the risks and provide clear guidelines for safely doing so. Her take-home message seems to be, do what you feel as a parent, not what you’re told—even when the people giving the advice are scientists like herself.