Q: My daughter is 2 years old and at night she wakes up every half hour. If I feed her three hours before she goes to bed, she doesn't wake up. Is this a problem?
A: If providing your daughter with a late evening meal provides you with a peaceful night's sleep and your daughter is not gaining weight too fast, we have no objection.
However, we would want to caution you that we can't make medical sense out of it. We can't say whether or not there is something wrong with your daughter. A doctor would need information about your daughter's eating, sleeping and behavior patterns before drawing conclusions. We can make a few general comments.
Almost all children older than a few months can easily get through the night without nourishment. Their livers store energy in the form of complex carbohydrates that convert, when needed, into the simple sugar glucose that "runs" the body. The normal human body can function quite well for many hours on these reserves, without new fuel deliveries in the form of food.
There are a few rare diseases that keep the liver from storing energy or from converting it back into fuel when needed. A child with one of those diseases might become distressed when too much time has passed since eating; she might even awaken from sleep.
But the pattern you describe does not fit such a disease, because you report that one evening meal three hours before bedtime seems to protect your child's sleep all night long.
A more frequent medical cause of night-time waking in young children is breathing difficulty when air passages are partially blocked by large tonsils or adenoids or for some other reason. Of course, food would not relieve that problem.
Most toddler sleeping problems are not caused by medical conditions, but are behavioral.
If they are not good at getting themselves back to sleep, they will fuss till they receive attention and comfort from an adult. You can help your daughter learn to get back to sleep by herself by making your interactions in the middle of the night reassuring, but brief and simple.
Dr. Wilson is director of general pediatrics at the Johns Hopkins Children's Center; Dr. Joffe is director of adolescent medicine.