It is not surprising that when a doctor is tired or hurried he or she is more likely to make a mistake. A new study published in JAMA Network Open provides some hard data on doctor performance as it relates to the prescribing of opioid (narcotic) analgesics. Opioids are still overprescribed, especially for migraine headache patients.

The researchers at the University of Minnesota discovered that doctors were 33% more likely to prescribe an opioid pain medicine at the end of the workday than in the beginning. If the doctor was running an hour or more behind schedule her or she was 17% more likely to prescribe an opioid. Prescribing of nonsteroidal anti-inflammatory drugs and referral to physical therapy did not display similar patterns. This was a very large study which means that the results are likely to be reliable. The study looked at 5,603 primary care practitioners who were involved in 678,319 primary care encounters for a painful condition.

Prescribing an opioid seems like a quick fix for a problem that saves doctors time, but usually is not be the best treatment for the patient.

Nobel Prize winner Daniel Kahneman in his book, Thinking Fast and Slow suggests that there are additional and easily correctable factors that may be contributing to poor decision making. Here are some quotes from the book.

“The most surprising discovery made by Baumeister’s group shows, as he puts it, that the idea of mental energy is more than a mere metaphor. The nervous system consumes more glucose than most other parts of the body, and effortful mental activity appears to be especially expensive in the currency of glucose. When you are actively involved in difficult cognitive reasoning or engaged in a task that requires self-control, your blood glucose level drops.

The bold implication of this idea is that the effects of ego depletion could be undone by ingesting glucose, and Baumeister and his colleagues have confirmed this hypothesis in several experiments… Restoring the level of available sugar in the brain had prevented the deterioration of performance.

A disturbing demonstration of depletion effects in judgment was recently reported in the Proceedings of the National Academy of Sciences. The unwitting participants in the study were eight parole judges in Israel. They spend entire days reviewing applications for parole. The cases are presented in random order, and the judges spend little time on each one, an average of 6 minutes. (The default decision is denial of parole; only 35% of requests are approved. The exact time of each decision is recorded, and the times of the judges’ three food breaks—morning break, lunch, and afternoon break—during the day are recorded as well.) The authors of the study plotted the proportion of approved requests against the time since the last food break. The proportion spikes after each meal, when about 65% of requests are granted. During the two hours or so until the judges’ next feeding, the approval rate drops steadily, to about zero just before the meal. As you might expect, this is an unwelcome result and the authors carefully checked many alternative explanations. The best possible account of the data provides bad news: tired and hungry judges tend to fall back on the easier default position of denying requests for parole. Both fatigue and hunger probably play a role.”

So for best results you may want to try to see your doctor right after lunch and hope that he or she had time to eat lunch.