Bed-wetting, SIDS, and emergency contraception.

This week, Dr. Sydney Spiesel discusses how to stop bed-wetting, the causes of SIDS, and the best emergency contraception.

Bed-wetting and the stages of sleep

Problem: To state the obvious, bed-wetting is no fun. When parents handle it poorly, and if it's frequent and lasts beyond age 5 or so, the condition can have a devastating effect on a child's sense of self, social relationships, and strivings for independence. Treatment is slow and frequently unsuccessful. On the upside, eventually the problem often cures itself: Only 10 percent of 7-year-old children wet the bed, and as every additional year passes, another 15 percent of the remaining sufferers stop.

Theories: A genetic component has long been suspected because there is a high likelihood that one or both parents of a bed-wetting child have a similar history. Emotional stress may also play a role. But the best-accepted theory has been that the central problem is a developmental disorder of sleep. Superdeep sleep seems a likely culprit because parents almost always say that it is virtually impossible to rouse a child who has wet the bed. In addition, parents who have outfitted their children with bed-wetting-treatment alarms (which ring as soon as they detect drops of moisture) often report that the child sleeps blissfully while the alarm wakes everyone else in the house (though, I should add, these alarms are the single most effective treatment).

New study: Recent research now casts doubt on the superdeep-sleep theory. The researchers studied 35 children between ages 6 and 14 who wet the bed almost every night, comparing them with 21 children who stayed dry. The research involved the use of the new tools in the study of sleep, including brainwave measurements, bladder measurements, and detection of bed-wetting without disturbing the child under study.

Findings: Contrary to expectations, children with severe bed-wetting problems spent more of their night hours in light sleep and fewer of them in the deep stages of sleep than children who do not have this problem. Instead, the children who habitually wet the bed all had significantly smaller bladder capacity than the children with whom they were compared. When nerve endings in their bladder walls detected a sense of fullness, a signal stimulated the bladder wall to contract and at the same time sent an activation signal to the brain, decreasing the depth of sleep. Yet the children couldn't make the final step and wake completely. The researchers speculate that perhaps this is a side effect of the bladder's long-term overstimulation of the brain's arousal center.

Implications: If that speculation is correct, perhaps we should move away from bed-wetting treatments that aim to wake the child—clearly a difficult task if the overloaded brain is blocking the final transition to wakefulness. An alternative might be treatments that minimize the signals sent from the bladder to the brain, so as to allow the bladder wall to tolerate a little more filling and to decrease the frequency of signals sent to the brain's centers that control arousal. Bladder capacity increases as children age (by about an ounce with every year of age) and, gradually, in response to stretching, but increased capacity alone doesn't reliably end bed-wetting.

SIDS and infection

Problem: Sudden infant death syndrome is one of the most terrifying possibilities new parents face. Despite a great deal of research, we still have no clear idea of the mechanism (or mechanisms) for the sudden death of a baby. Nonetheless, epidemiological research points to certain practices to avoid. For example, it is clear that an infant put to sleep on his back, without any props or supports, is much safer than a baby who is allowed to sleep face down. It is also clear that putting a sheepskin in the baby's crib or allowing a sleeping baby's face to be covered increases the risk of SIDS, as does exposure to tobacco smoke. (The use of pacifiers, on the other hand, reduces the risk.)

Question: What other risk factors are there? In England and Wales, all SIDS cases are deeply and intensively studied, and a recent report based on this research suggests that an undetected bacterial infection might sometimes play a role.