By Randy Dotinga

TUESDAY, April 11, 2017 (HealthDay News) -- When a bedside alarm goes off in a child's hospital room, anxious parents expect nurses to respond pronto.

That rarely happens, however, and a new study helps explain why.

Researchers found that nurses are usually quick to react when alarms are urgent. But, they're slower to respond at the end of the workday or when they suffer from "chronic alarm fatigue."

Also, having parents present doubled the response time on average, the study found.

But, delayed response time didn't threaten any of the 100 patients evaluated in the study, the researchers said. And just half of 1 percent of more than 11,000 alarms analyzed were deemed "actionable," or crucial.

"The nurses were overall doing a great job predicting which alarms were going to be important," said study lead author Dr. Christopher Bonafide, an assistant professor of pediatrics with the Children's Hospital of Philadelphia.