When your pager vibrates at 7 o’clock in the morning, it is unlikely to be alerting you of good news. It may be a parent who assumes that because his child’s medical home has evening office hours that there will be a receptionist sitting there at sunup to help him make an appointment for a nonurgent complaint. Or, it may be a call from a parent who knows that she doesn’t have a medical emergency on her hands, but who would like your advice about whether she should take a day off from work or send her child to day care.

But, an uncomfortable number of daybreak calls come from parents with what eventually turns out to be a desperately ill child. I have witnessed those scenarios often enough that even though I am retired, I break into a cold sweat when the home phone rings anytime between 6 and 7 in the morning.

A study from Wake Forest University, Winston-Salem, N.C., published in the November 2014 issue of Pediatrics, supports my long-standing discomfort with patients who present in the early morning. (McCrory et al. “Off-Hours Admission to Pediatric Intensive Care and Mortality,” Pediatrics 2014;134:e1345-e1353 [doi: 10.1542/peds.2014-1071] ). In a retrospective study of nearly a quarter of a million admissions to 99 perinatal ICUs over a 3-year period, the investigators discovered that admission in off-hours and weekends “does not independently increase the odds of mortality.”

However, they found that admission from 6 to 11 in the morning is “associated with an increased risk of death.” This may not have been the result the investigators were expecting, and their analyses don’t suggest a cause. In the discussion portion of the paper, they offer some explanations that are in sync with my observations. First, ICUs are generally fully staffed 24-7-365. While the lights maybe dimmed slightly, there is seldom a diurnal variation in the attentiveness and quality of the caregivers in an ICU. Contrast this to an ordinary medical/surgical floor on which the staffing levels drop precipitously when the sun goes down. The skeletal staff is usually working in the dark, resorting to flashlights and ankle-level lighting to make their observations. And … things are missed. Things like skin-color changes and the quality of respirations that become obvious when the morning shift arrives and the lights go on. “Holy s**t! This patient needs to be in the PICU!” And, the PICU now receives a patient at 7:30 a.m. who has a greater odds of mortality because the illness has percolated in the dark overnight.

The same phenomenon occurs in the outpatient setting. At night, sleep deprivation may cloud a parent’s observational skills. The lights in the bedroom may have been left off in hopes of keeping the child more comfortable. The parent may have called the doctor and been shunted to a triage nurse who is unfamiliar with the family and whose algorithm fails at a critical branch point. Or, the call may have been fielded by an answering service that is more interested in protecting its client’s sleep than serving the needs of the caller.

Or the parent may have spoken to the doctor early in the evening, but was hesitant to call again and wake her when the child’s condition changed. House officers can fall into the same trap when their misplaced concern about the sleep needs of the physician to whom they report prevents them from making a critical call for help.

Again, the result is that when the sun comes up, a child whose illness might have been more easily managed in the PICU at 2:30 a.m. doesn’t arrive in the unit until those deadly hours between 6 a.m. and 11 a.m. While there may be diurnal variations in the inherent mortality of some pathological conditions, this study from North Carolina suggests that when the lights go out, critical observations go unmade and so do wise decisions.

Dr. Wilkoff practiced primary care pediatrics in Brunswick, Maine, for nearly 40 years. He has authored several books on behavioral pediatrics, including “How to Say No to Your Toddler.” E-mail him at pdnews@frontlinemedcom.com .