Nicotine may impair a molecule that's necessary for arousing people and other animals from sleep, a study of mice finds. The effect could account for the heightened risk of sudden infant death syndrome (SIDS) in babies born to women who smoked during pregnancy. This well-established link has never been fully explained.
SIDS, also called crib death or cot death, occurs when babies suffocate accidentally or stop breathing in an event called sleep apnea. Surprisingly, these babies don't struggle to breathe sufficiently when they're deprived of oxygen.
At the core of the normal alert system is acetylcholine, a chemical that among other duties transmits nerve signals. Low concentrations of oxygen in the blood appear to trigger the binding of acetylcholine to a specific receptor molecule on cell surfaces, which then initiates a series of signals that spur the respiratory system to crank up. "These are internal regulatory mechanisms for arousal," says Jean-Pierre Changeux, a m