The problem of patient peaks and valleys isn’t new. To make sure they were ready to meet surges in demand, hospitals used to build more beds. Now nobody, even the top hospitals, can afford to keep adding beds and nurses. Neither can they afford the consequences of the status quo. Johns Hopkins Hospital found in 2009 that during a surge in new patients admissions, the rate of intensive care unit re-admission—when patients who have been released have to come back—would rise as high as 500%.

So it sounds like an impasse. Hospitals are correct in saying that they can’t afford higher staffing levels. But as long as nurses are subjected to periodic excessive patient demand (which will only grow more frequent with baby boomers in the mix), the push for adequate levels of care will continue.

Fortunately, there is an answer. It begins if one asks why hospital-bed capacity fluctuates on a daily basis. Lucky is the patient who is admitted during a low point in demand for beds, usually at the beginning of the week. Unfortunate is the one who gets admitted during a peak, usually toward the end of the week, when all hospital resources (particularly nurses) are stretched thin. But why do patients arrive in clusters on a particular weekday? Do they break more legs on Thursdays than on Tuesdays?