Reforms imposed five years ago to rein in the long work hours put in by doctors-in-training don’t go far enough to reduce risks to patients and to the sleep-deprived trainees, according to a report released Tuesday.

The report, produced by the Institute of Medicine, an arm of the National Academies, said medical residents ideally should work no longer than 16 consecutive hours, considerably less than the 30-hour shifts now allowed.

If they have to go over 16 hours, they should be required to take a five-hour nap, which would count toward a maximum 30-hour cap, the report said.

The institute also recommended that any hours spent moonlighting should count against the maximum 80 work hours allowed per week (averaged over four weeks), which could eliminate a popular practice for residents, who make about $40,000 a year and often are burdened with large education loans.

Dr. Peter Lurie of the consumer advocacy group Public Citizen, said the mandated five-hour nap was a ruse to make sure residents could still work a 30-hour shift.

“No one is going to get anything approaching five hours of sleep,” Lurie said. “It’s just an elaborate effort to keep alive the current guidelines while requiring organized medicine to make as few changes as possible.”

Residents are medical school graduates who care for patients under the supervision of experienced physicians.

A form of apprenticeship, residency is notorious for brutal hours and minimal pay. The period of residency can last from three to seven years, depending on the specialization.

The new recommendations would add costs. Hiring additional staff to allow residents to work shorter shifts would cost about $1.7 billion annually, according to the panel of medical experts that prepared the institute’s report.

Saying that reduced hours would not alone improve doctor training or patient safety, the report proposed protocols to improve handoffs of patient cases from one resident to another during shift changes, a period notorious for introducing errors.

It also called for closer supervision of residents by fully licensed physicians and warned against merely expecting residents to take care of the same number of patients over a shorter period of time.