Your newborn doesn't eat at the same times every day, naps here and there, and is alert and playful at all hours. What's the harm?

A recent study found a connection that shows up years later.

An infant who ate, played and took comfort at irregular times from day to day was much more likely to show symptoms of anxiety when he was of junior-high age, according to a collaborative study by researchers from the University of Pittsburgh and the University of Wisconsin.

The work led by researchers from Pitt's School of Medicine in collaboration with those from Wisconsin's School of Medicine and Public Health was recently published by Psychiatry Research.

It has been shown previously that psychiatric ill health, especially symptoms related to depression and anxiety, are associated with disruption of the 24-hour biological clock, also known as the circadian system. This study was designed to determine if infants' regularity or lack thereof could predict depression and anxiety symptoms when they were older.

The research teams followed 30 girls and 29 boys for 13 years starting at age 1 month, when parents, using sleep as the baseline behavior, charted the starting times for feeding, playing, diaper changing and taking comfort for two consecutive weeks. Pitt researchers developed the diary tool called the Baby Social Rhythm Metric.

When their children were 6, 7, 9, 11 and 13, the mothers were interviewed by researchers, answering questions designed to reveal symptoms of anxiety and depression. All the data were gathered as part of the University of Wisconsin's long-term Wisconsin Study of Families and Work co-directed by Marilyn J. Essex of the University of Wisconsin-Madison, a lead co-author of the Psychiatry Research article.

"What we find is the regular-routine babies are less likely to be anxious when they are at school, and this is likely due -- obviously there might be other forces [too] -- to genetic or developmental differences where the biological clock is better developed at 1 month in these babies," said Timothy H. Monk, another lead co-author of the study and professor of psychiatry in Pitt's School of Medicine.

"There was no evidence of depression," Dr. Monk added.

At separate times over the 13 years, the children's sociability and concentration also were measured. Sociability was measured by how much the babies liked cuddling and smiling at 4 and 12 months. Concentration, or directed attention, was measured during a two-hour home visit by a researcher and camera-operator spent watching mother-child interaction tasks when the children were 4 1/2 years.

The study found that good sociability and concentration were "pathways," or mediating factors, that corresponded with fewer symptoms of anxiety down the road.

"Given the age of the child at the time they were measured, they likely reflect or are biologically based characteristics," said co-author Linnea Burk, clinical assistant professor in the department of psychology at Wisconsin-Madison.

"But they also -- particularly concentration, which was measured in preschool -- that also most likely reflects an environmental component as well. Sociability was measured when they were infants, so that's probably more temperamentally based."

Tiffany Field, the psychologist who directs the Touch Research Institute at the University of Miami, said the findings of the Pitt-Wisconsin study made sense.

"There are other data that show how organized a baby is contributes to childhood factors like IQ scores," she said.

"I'm just saying if you're disorganized early on, you're going to have attention problems, and if you have attention problems, you're going to have a lot of anxiety because you know you're not doing well in school. So the data is not surprising."

But, Dr. Field said, "I think they could have done more with the data. ... Usually for a paper you try to stay very close to the data. What they failed to remember is that parents were filling out all the scales, so it was all from a parent's perspective. So they're not giving the parent much credit for the child's rhythmicity."

But Drs. Monk and Burk did so in post-publication interviews.

"Certainly parents who ... have a less structured lifestyle could also be contributing to the behavioral irregularities of a child, so it might be more difficult for a child to have a regular schedule," Dr. Burk said.

"The analogy we always use is that somebody who has severe asthma may find a move to Arizona is helpful. It won't cure the asthma, but it will be less troublesome to them," Dr. Monk said. "One can use that analogy in enhancing 24-hour time cues, having regular routines and thereby lessening the problems that may come from genetics."

Dr. Monk is especially interested in the circadian system and would like to leverage the findings in this study to a large one based in genetics.

"The research into the biological clock is at a very exciting stage where we know now that there are huge genetic influences. For example, we know if you are a 'morning lark' or a 'night owl,' and we know even the genes involved in that difference," he said.

"It is reasonable but not proven there might be an equivalent genetic marker that governs whether somebody is highly regular or irregular in routines. What I'd like to do in collaboration with colleagues in genetics is test that out in a large sample of people."

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