With permission to nap, doctors stay more alert.

While on call, doctors-in-training often spend 30 hours at a stretch at a hospital. Although they may catch catnaps when they're not needed at a bedside, these interns develop fatigue that can pose risks to them and to their patients.

A new study tested the effects of giving such doctors greater permission to nap--by permitting them to hand off to another doctor the pager that summons them to the next patient. Increases in the amount of sleep the interns get and fatigue reduction could outweigh any risk of miscommunication about needed care that might occur from handing off patients, according to researchers led by Vineet Arora of the University of Chicago Hospital.

The investigators asked 38 doctors-in-training to wear motion meters on their wrists for 1 month. The meters recorded how much time each intern slept.

For half the study, a staff doctor was available nightly between midnight and 7 a.m. to spell any on-call intern requesting time to nap.

When given that option, interns slept a total of 185 minutes on average per night, compared with 144 minutes on nights when they didn't have a backup. They also reported having less fatigue when nap breaks were permitted.

In the June 6 Annals of Internal Medicine, Arora's team suggests that interns with increased nap time may be capable of staying on call for more than 30 consecutive hours, the current nationwide limit.