My 4-month-old daughter is just getting over her first cold and I also just started her on rice cereal once a day, at night. Suddenly she is not sleeping through the night when for weeks she had been sleeping all night. Do you think her unusual wakefulness at night could be due to the cereal? And is there anything extra I could do to help her sleep through the night again? How much cereal should I be giving her?
I'm glad to hear you and your 4-month-old have presumably made it through her first cold! That said, there are several things that come to mind when you ask about sleeping and eating changes at this age. While I can share with you some general thoughts, it will be most useful to enlist the help of your own pediatrician to figure out whether or not your baby's changes in sleeping and eating habits are truly related to each other or her recent illness.
I always make sure to tell new parents facing their child's first cold that it is not uncommon for children to not only be a bit off routine in the day or two before their symptoms start to appear, but also in the several days (or weeks) after the symptoms seem to have resolved. Eating and sleeping routines are most commonly affected by illnesses. I typically find that babies may be less interested in solid foods when they have a common cold. It is most important to focus on keeping babies well-hydrated during periods of illness, so a lack of interest in solid foods isn't usually much of a problem. I also find that sleep routines are disturbed by something as seemingly simple as a snotty nose cold—especially in infants who may not yet have even established a good sleep routine—because of difficulty breathing and the mucus drainage and irritation that we all experience when trying to sleep with a head cold.
For a previously good sleeper at the age of 4 months, frequent waking may also simply be from a change in your bedtime routine. When babies have a cold, it's very common and understandable for parents to offer additional TLC. If this extra loving attention happens to include additional rocking, holding, and/or nursing/bottle feeding at bedtime, then parents may find themselves faced with a baby who has begun to be dependant on these sorts of sleep aids to fall asleep (a common sleep problem I've addressed here) even after her cold symptoms have resolved.
And finally, any time new foods are introduced into a baby's diet, it's worth taking note of and discussing with your pediatrician any resulting changes in her appetite, symptoms, behavior, or feeding routines. These can include, among other things, such symptoms as fussiness, gassiness, rashes, diarrhea, or blood in the stools.