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Managing Sleep and Fatigue in Today’s
Healthcare Environment Tricks of the Trade
Scott Shappell, Ph.D. Clemson University
92nd Annual Meeting of the American Association of Thoracic Surgery
How tired are you, really???
The worst person to is the person that you are worried about!
Increased reaction time • Timing errors in response sequences • Less smooth control
Reduced attention • Preoccupation with single tasks or elements • Reduced audiovisual scan
Diminished memory • Forget peripheral tasks • Revert to “old” habit patterns
Withdrawn mood • Less likely to converse • Less likely to perform low-demand tasks
Effects of Fatigue on Performance
• We have an intrinsic biological clock with a cycle of roughly 24-25 hours.
• Many bodily functions cycle about these daily circadian rhythms
a) Blood Pressure b) Heart Rate c) Core Body Temperature d) Others...
• Perhaps most important is that performance also cycles about normal circadian rhythms.
• Given the typical circadian cycle, performance peaks between 1200 and 2100 hours and falls to a minimum circadian trough between 0300 and 0600 hours.
Circadian Rhythms
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Circadian Rhythms
While the body clock is inherently capable of monitoring the passage of time, it differs from most clocks in that it is flexible and must be set, or synchronized, before it can accurately predict the timing of events.
Entrained by external synchronizers, Zeitgebers a) Sunrise-Sunset b) Ambient Temperature c) Meals d) Social Cues
Circadian Rhythms
• Deficits in performance, mood, motivation, and behavior
• Sleep disturbances
• Lassitude, anxiety, irritability, depression
• Slow reaction times, defective memory for recent events, errors in computations, and a tendency to accept lower standards of performance.
Circadian Desynchronization “Jet Lag”
Circadian Desynchronization “Jet Lag”
• Rapidly traveling from one time zone to another, the body clock and rhythms it controls must resynchronize to the local geophysical and social zeitgebers.
• Eastward travel shortens the day.
• Westward travel lengthens the day.
• Resynchronization occurs much more rapidly when traveling west
Our sleep/wake cycle is closely tied to our circadian body temperature
a) Cave studies
Sleep
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Stages of Sleep
Stages of Sleep
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Circadian Rhythms
Our sleep/wake cycle is closely tied to our circadian body temperature
• Cave studies
The duration and “quality” of sleep is dependent upon body temperature
• People sleep longer and report a better night’s sleep when they retire near the temperature trough.
It is the timing of sleep, not necessarily the amount of sleep, that is most significant.
Sleep
• The circadian rhythm of sleepiness (MSLT) is remarkably similar to the circadian rhythm of body temperature.
• There are essentially two times when your body is prepared to sleep.
1) The most obvious is between 2200-0600
2) Post-prandial dip
When is the Best Time to Sleep?
How Much Sleep Do You Really Need?
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Effect on Complex Mental Operations
How Much Sleep Do You Really Need?
Baseline (8 hrs)
Days on Experimental Schedule
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How Much Sleep Do You Really Need?
How Much Sleep Do You Really Need?
• Sleep requirements vary among individuals.
• A minimum of 5 hours of uninterrupted “core” sleep during the circadian trough is necessary to maintain performance in the lab.
• Sleeping in excess of 10 hours may produce sleep drunkenness.
• When physical and mental workload exceed normal limits, the minimum amount of sleep needed to sustain performance is more.
Napping
• When sleep is not available or shortened by operational concerns, strategic naps are a viable alternative.
• Even naps as short as 10 min are restorative in nature
• Long naps (typically greater than 1 h) may leave the individual feeling more tired than before napping (Sleep Inertia)
a) Sleep inertia may last 5-20 min upon awakening
• Practice Napping
Napping
Countermeasures to Fatigue
Pharmacological
a) Caffeine
b) Meth-amphetamine
c) Amphetamine
d) Methylphenidate
Non-Pharmacological
a) Tyrosine
Countermeasures to Insomnia
Pharmacological
a) Barbiturates
b) Benzodiazepines
c) Alcohol
d) Antihistamines
Non-Pharmacological
a) Keep a routine
b) Vigorous exercise
b) Warm baths
c) Tryptophan
