The Effects of Long Doctor Work Hours | Visualized Science

Reviewed by The Clinical Committee

May 13, 2019

  • When doctors work long hours, they feel sleepier and less alert.

  • They have slower reaction times and drive as if they've had a few drinks.

  • This has potential implications for patients being treated by tired doctors.

Effects of Long Work Hours on Driving

Effects of Long Work Hours on Driving

Figure 1: Effects of Long Work Hours on Driving. Volunteers who worked overnight shifts had significantly worse driving ability than those who had not. Volunteers were evaluated in a driving simulator. Their ability to stay in their lane and stay at a constant speed were measured. A 3rd group was given vodka tonics to simulate drunk driving. Researchers found that volunteers who worked overnights also drove worse than the "drunk driving" group.

Doctors are notorious for working long hours. Illness and emergencies can occur at all hours of the day; they don't wait for bank hours. Unlike most other professions, at least one doctor needs to be available at all hours in case of emergencies or overnight issues.

In a study published by JAMA, doctors who had just finished an overnight shift were tested against doctors who worked fewer overnight shifts in order to see the effects of long hours on alertness and reaction time.

They found that when it came to driving, volunteers who had worked an overnight shift were not surprisingly worse at driving than volunteers who had not.

To compare sleepy driving to drunk driving, they also gave some other doctors vodka tonics. They found that doctors who had worked overnight drove worse than the doctors given 2 drinks. They measured this with a driving simulator to see whether the volunteers could drive a car in a straight line and at a constant speed.

Source: Neurobehavioral Performance of Residents After Heavy Night Call vs After Alcohol Ingestion

What "On Call" Means for Doctors

Doctors who are "on call" typically work an additional shift where they attend to sick patients during non-work hours. In a hospital, patients are sick 24/7. In order to provide around-the-clock medical care, at least one doctor needs to be on-call. Often there are multiple on-call doctors for each specialty in a larger hospital.

Evidence Score:


Methods - This study directly compared two similar groups of medical residents, who were presumably somewhat randomized by their residency work schedules.


Effect Size - This study showed significant and clinically relevant effects. The size was particularly relevant to driving performance.


Sample Size - While the sample size was small (n=34) in this study, it was sufficient to collect consistent and useful data.

Reaction Time vs Sleep Deprivation in Doctors

Reaction Time vs Sleep Deprivation in Doctors

Figure 2: Reaction Time vs Sleep Deprivation in Doctors. Doctors who had worked overnight shifts had a reaction time of 242 milliseconds. This was slightly faster than doctors given alcohol, who had a reaction time of 248 milliseconds. Both groups were significantly slower than less overworked doctors who had a reaction time of 226 milliseconds.

Doctors who worked overnight shifts also had a slower reaction time, as measured by the Psychomotor Vigilance Test. They had reaction times similar to doctors who were given 2 alcoholic drinks.

Some of the longest work hours are found in Surgeons, who often take care of very sick patients recovering from surgery. During these long shifts, they also sometimes perform surgeries. This research raises questions about whether long working hours for surgeons is a potential patient safety issue, given the slower reaction time and alertness of overworked doctors.

Source: Neurobehavioral Performance of Residents After Heavy Night Call vs After Alcohol Ingestion

Sleepiness and Alertness After Overnight Shifts

Sleepiness and Alertness After Overnight Shifts

Figure 3: Sleepiness and Alertness After Overnight Shifts. Doctors who had just worked overnight not surprisingly rated themselves as significantly sleepier, with a 4.6/7 on a Stanford Sleepiness Scale, than doctors who had not, with a 2.3/7 on a Stanford Sleepiness Scale. They also rated themselves as less alert on a visual analogue scale. (68.4 vs 31.6)

Doctors not only performed worse, they also felt worse themselves.

Doctors after an overnight shift were rated as far sleepier and far less alert, according to the Visual Analogue Scale.

Source: Neurobehavioral Performance of Residents After Heavy Night Call vs After Alcohol Ingestion

Visual Analogue Scale

Visual Analogue Scales are used to measure factors that lie on a spectrum or continuum. They are most commonly used to measure pain. Typically, a subject is asked to point to where they feel they stand on a line between two points, for example no pain and the worse imaginable pain. This distance is then used to compare values between different patients and different groups.

Key Takeaways

This research shows that overnight shifts are not only miserable, they are also potentially dangerous, particularly when driving back home.

The doctors who were in the control group also had the occasional overnight shift, but at much lower frequencies.

While overnight shifts are necessary in many industries, including medicine, this research points to significant drawbacks to having too many too often.

Related: Physician Burnout

The practice of medicine can be brutal at times with long hours and very sick patients.

Doctors are getting burned out and its affecting patients. A new study shows that burned out doctors have twice the rate of patient safety incidents and low professionalism. Burnout has been increasing in mahy specialties. Some physician specialties have it worse than others.

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Effects of Physician Burnou...

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