Managing Sleep and Fatigue in Today s Healthcare Environment Tricks of the Trade 92 nd Annual Meeting of the American Association of Thoracic Surgery Scott Shappell, Ph.D. Clemson University
How tired are you, really??? The worst person to is the person that you are worried about!
Effects of Fatigue on Performance 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tasks or elements Reduced audiovisual scan Diminished memory Forget peripheral tasks Revert to old habit patterns Withdrawn mood Less likely to converse Less likely to perform low-demand tasks
Circadian Rhythms 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.
1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 0100 0200 0300 0400 0500 0600 0700 0800 0900 1000 PERFORMANCE Circadian Rhythms OPTIMAL PEAK ALERT Circadian Trough SLEEPINESS WORST NADIR SLEEPY Time of Day (24 hour)
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 Desynchronization Jet Lag 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 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
Sleep Our sleep/wake cycle is closely tied to our circadian body temperature a) Cave studies
1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 0100 0200 0300 0400 0500 0600 0700 0800 0900 1000 PERFORMANCE Circadian Rhythms OPTIMAL PEAK ALERT Circadian Trough SLEEPINESS WORST NADIR SLEEPY Time of Day (24 hour)
Stages of Sleep
Stages of Sleep
1100 1200 1300 1400 1500 1600 1700 1800 1900 2000 2100 2200 2300 2400 0100 0200 0300 0400 0500 0600 0700 0800 0900 1000 PERFORMANCE Circadian Rhythms OPTIMAL PEAK ALERT Circadian Trough SLEEPINESS WORST NADIR SLEEPY Time of Day (24 hour)
Sleep 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.
When is the Best Time to 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
Performance Percent of Baseline How Much Sleep Do You Really Need? 125 72 Hours of Total Sleep Deprivation: Effect on Complex Mental Operations Better 100 75 50 25 0 Worse 0 24 48 72 Sleep Deprivation (Hours)
Response Speed How Much Sleep Do You Really Need? Better Baseline (8 hrs) Worse Days on Experimental Schedule
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.
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
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
Sweet Dreams! Scott A. Shappell, Ph.D. Clemson University HFEng@clemson.edu (405)640-5479