On The Clock

Timing is everything when it comes to boosting the benefits of your baby's vaccinations.


The next time you need to schedule a vaccination for your baby, opt for an afternoon appointment. A new study found that infants slept more during the next 24 hours if they got their shots later in the day—and a long, sound sleep is believed to boost a vaccine's effectiveness.

In the study of 70 2-month-olds, about half of the moms were also told to give acetaminophen (Tylenol) before and after the shots, while the others were told to follow their pediatrician's advice, which was usually to give acetaminophen only if the child developed a fever or fussiness. Regardless of whether infants were given acetaminophen, babies vaccinated after 1:30 p.m. slept longer during the next 24 hours.

Experts say they don't know for sure whether parents should avoid giving babies acetaminophen before and after shots. In the study, babies whose temperatures rose about half a degree slept longer than other infants. A slight increase in temperature is a sign that they body is responding as it should to the vaccine, says study author Linda Franck, a nurse scientist at University of California, San Francsico.

With the jury still out on acetaminophen, one thing is for sure: It's a good idea to make sure your baby is well rested leading up to and after immunizations. "Sleep is really important to immune function," says Franck.

Check out our First Vaccines page for what to expect with your baby's first shots.

— Jennifer Goodwin