Sleep Deprivation
Well-defined periods of vulnerability to sleep have been identified
in humans. The major peak occurs between
2 and 7 AM, and a smaller peak occurs in the midafternoon.
[112]
These peaks appear to be enhanced by irregular
work schedules and sleep disruption, and they may also contribute to diurnal variation
in the frequency of mishaps. For example, single-occupant motor vehicle accidents
occur with alarming regularity in the early morning. Their timing is attributed
in part to this cycle. Similar relationships have been observed in the timing of
catastrophic industrial accidents. The nuclear reactor accidents at Three Mile Island,
Chernobyl, and two other sites in the United States all began between 1 and 5 AM.
Human error was a significant factor in each mishap. Critical errors in judgment
involving the Challenger Space Shuttle accident were made in the early morning hours
by personnel working irregular shifts. Again, human error was a contributing element.
Although none of these accidents can be conclusively attributed to sleep-related
processes, all involved a lack of proper response by well-trained personnel working
to the best of their abilities at the time of the accident.[113]
On the basis of these observations, the Committee on Catastrophes, Sleep, and Public
Policy of the Association of Professional Sleep Societies has made the following
recommendations:
- Management should be made aware that performance errors are more common
between 1 and 8 AM.
- Programs should be developed to identify signs of sleep-related error.
- Because inadequate sleep or irregular sleep patterns enhance the tendency
for error, work hours should be limited to permit adequate sleep.[113]
Despite mounting evidence regarding the detrimental effects of
sleep deprivation on work performance, altered patterns of sleep continue to be a
way of life for anesthesiologists.[114]
Numerous
studies have attempted to quantify the consequences of sleep deprivation on the practice
of medicine.[115]
Many of these studies measure
clinical surrogates such as cognitive function, dexterity, and vigilance, whereas
others focus on the effect of sleep deprivation and fatigue on physician well-being.
Few have attempted to measure a direct effect on patient care.[116]
[117]
The chronic fatigue of being on call every third or fourth night
has been shown to have a negative impact on the cognitive function of university
house staff on standardized tests.[118]
In the
practice of anesthesia, sleep deprivation may have subtle effects on vigilance in
the operating room and may contribute to critical incidents.[119]
However, when patient simulation was used to study the effects of sleep deprivation
on the psychomotor and clinical performance of anesthesia residents, psychomotor
performance and mood were found to suffer, whereas clinical performance did not.
[120]
This lack of correlation between psychomotor
and cognitive testing and clinical performance has been noted in the surgical literature
also. Although a surgeon's psychomotor performance on simulated laparoscopic tasks
has been shown to decline after only 17 hours on call,[121]
a retrospective review of postoperative complications did not show a significant
increase when surgery was performed by "post-call" resident physicians.[122]
Sleep deprivation has been shown to have an impact on physician
well-being. The most obvious consequence of sleep deprivation on physician well-being
is the increased frequency of automobile accidents in post-call house staff.[123]
[124]
Less obvious is the effect of sleep deprivation
on physician mood. Interns in the United States report an increased incidence of
fatigue and depression after a night on call,[125]
and their incidence of major depression has been shown to be higher than that expected
in an equivalent age group in the general population.[126]
A study of house officers in England showed that sleep deprivation resulted in an
adverse effect on mood, as well as cognitive testing of vigilance and reaction time.
[127]
A general consensus in the literature is that physicians can no
longer afford to ignore the possible effects of fatigue and sleep deprivation on
patient care. Although further studies are needed to determine the full impact of
sleep deprivation on clinical performance, there is some evidence that eliminating
these factors can in fact improve patient care. For example, resident physicians
were found to make fewer medication errors (16.9 versus 12 per 100 patients discharged)
after their work hours were adjusted to minimize sleep deprivation and fatigue.
This study in a university-affiliated Veterans Affairs Medical Center also demonstrated
a decrease in the length of patient stay and the number of laboratory tests ordered.
[128]
The Future
The sensationalism of the Libby Zion case has had a tremendous
influence on how medicine will be practiced in the future. Although the facts of
the case suggest that insufficient attending physician supervision and excessive
patient workload were the root causes of the adverse outcome, subsequent investigations
considered resident fatigue and sleep deprivation to be contributing factors. As
a result, in 1989 the state of New York limited resident work hours.[129]
In July 2003, the Accreditation Council for Graduate Medical Education (ACGME) adopted
similar resident work hour limitations for all accredited residency programs. The
restrictions on resident duty hours for each of the ACGME-accredited specialties
can be found at ftp://www.acgme.org/new/dutyhrequirem.pdf.
Limitation of physician work hours remains controversial. There
are those in the profession who worry that patient care will suffer as a result.
They fear that "shift work mentality," combined with increased transfer of patient
care, will result in decreased professionalism and continuity of care. Although
future studies are needed to determine the full impact of physician work hour regulations
on patient care, there is no doubt that sleep deprivation, overwork, and fatigue
are detrimental to physician well-being, the patient-physician relationship, and
physician cognitive function and monitoring vigilance.[130]
[131]
[132]
[133]
