circadian rhythms and shift work 1 vicken y. totten md: vicken y. totten md: emergency physician...
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Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 11
Circadian Rhythms Circadian Rhythms and and
Shift WorkShift Work
Circadian Rhythms Circadian Rhythms and and
Shift WorkShift Work
Vicken Y. Totten MD:Vicken Y. Totten MD: Emergency Physician Emergency Physician
and Career-long Shift Workerand Career-long Shift Worker
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 22
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 33
SLEEP in literatureSLEEP in literatureSLEEP in literatureSLEEP in literature
Sleep, that knits the ravell'd sleave of care,Sleep, that knits the ravell'd sleave of care, The death of each day's life, sore labour's bath,The death of each day's life, sore labour's bath, Balm of hurt minds, great nature's second Balm of hurt minds, great nature's second
course,course, Chief nourisher in life's feast.Chief nourisher in life's feast.
• - Shakespeare, Macbeth, Act II, Scene I- Shakespeare, Macbeth, Act II, Scene I
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 44
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 55
Goals and Objectives: Goals and Objectives: Goals and Objectives: Goals and Objectives:
Describe normal sleep structure Describe normal sleep structure Discuss Circadian Rhythm Disorders Discuss Circadian Rhythm Disorders Describe types of shift work patternsDescribe types of shift work patterns Offer concrete shiftwork suggestionsOffer concrete shiftwork suggestions Provide a resource list Provide a resource list
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Biologic Rhythm ControlBiologic Rhythm Control
Innate rhythms poly-genetically Innate rhythms poly-genetically determined determined
Master clock in suprachiasmatic nucleus Master clock in suprachiasmatic nucleus of the rostro-ventral hypothalamus. of the rostro-ventral hypothalamus.
Mediated by light/dark cycles via Mediated by light/dark cycles via cryptopsin receptors in retina, skin and cryptopsin receptors in retina, skin and possibly pituitarypossibly pituitary
Humans: Day = alert / Night = sleep. Humans: Day = alert / Night = sleep.
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Biologic rhythmsBiologic rhythms
All body systems change All body systems change rhythmicallyrhythmically
90 minute alertness cycle90 minute alertness cycle Monthly fertility cycleMonthly fertility cycle Sleep/wake generally 23-26 hour Sleep/wake generally 23-26 hour
cyclecycle
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Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 99
Rhythm disordersRhythm disorders
Normally, biologic cycles kept in synch Normally, biologic cycles kept in synch by signal substances such as by signal substances such as melatonin, cortisol and othersmelatonin, cortisol and others
Disruption in these systems have Disruption in these systems have profound health implications. profound health implications.
Disrupted by both internal and Disrupted by both internal and external signalsexternal signals
Cycles re-synchronize at different Cycles re-synchronize at different ratesrates
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Circadian disruption Circadian disruption
De-synchronization of innate De-synchronization of innate biologic / circadian cycles. biologic / circadian cycles.
Chronically in shiftwork and briefly Chronically in shiftwork and briefly from jetlag. from jetlag.
Medicine is far behind industry in Medicine is far behind industry in recognizing the implications of shift recognizing the implications of shift work work
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Causes of circadian rhythm Causes of circadian rhythm disorders disorders
GeneticsGenetics Medications Medications PregnancyPregnancy Shift work Shift work time zone changes time zone changes
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Normal Sleep Architecture: Normal Sleep Architecture: Stages of sleepStages of sleep
Normal Sleep Architecture: Normal Sleep Architecture: Stages of sleepStages of sleep
Non-REM (NREM) sleep - Stages I-IV Non-REM (NREM) sleep - Stages I-IV brain idle, body mobile brain idle, body mobile
REM - Body paralyzed, Brain active REM - Body paralyzed, Brain active (more metabolically active than (more metabolically active than during waking)during waking)
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 1313
Stage 1 - transition period. Stage 1 - transition period. Stage 1 - transition period. Stage 1 - transition period.
Normally 10 minutes. Eyes rove. Normally 10 minutes. Eyes rove. Most people awakened during Stage Most people awakened during Stage
1 claim they are not asleep.1 claim they are not asleep. ““Micro-Sleeps” Micro-Sleeps” Driving while fatiguedDriving while fatigued
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Stage 2 - Deeper, fewer eye Stage 2 - Deeper, fewer eye movements. movements.
Stage 2 - Deeper, fewer eye Stage 2 - Deeper, fewer eye movements. movements.
Shallowest restorative sleep. Shallowest restorative sleep. About half of adult sleep in Stage 2. About half of adult sleep in Stage 2. 20 min. before progressing to next 20 min. before progressing to next
stage. stage.
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Stages 3/4 - Slow wave Stages 3/4 - Slow wave sleep (SWS), (delta sleep) sleep (SWS), (delta sleep) Stages 3/4 - Slow wave Stages 3/4 - Slow wave
sleep (SWS), (delta sleep) sleep (SWS), (delta sleep) Most restorative & restful; vital for Most restorative & restful; vital for
physical recuperation. physical recuperation. Majority occurs early in the sleep Majority occurs early in the sleep
period.period. Difficult to arouse from SWS.Difficult to arouse from SWS. First stage to be “made up” after sleep First stage to be “made up” after sleep
deprivation.deprivation. SWS deprivation causes fatigue, SWS deprivation causes fatigue,
muscle aches. muscle aches.
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REM sleepREM sleepREM sleepREM sleep brain on, body off. brain on, body off. Vital for psychological well-being; Vital for psychological well-being; Isolated REM deprivation -> 1Isolated REM deprivation -> 1stst
irritability -> psychosis -> death irritability -> psychosis -> death EEG similar to wakefulness. EEG similar to wakefulness. Dreams, irregular pulse, respiration, Dreams, irregular pulse, respiration,
increased BP, loss of muscle tone, increased BP, loss of muscle tone, and absent spinal reflexes. and absent spinal reflexes.
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REM sleepREM sleepREM sleepREM sleep First episode occurs after 90-120 minutes First episode occurs after 90-120 minutes
of NREM sleep. of NREM sleep. Recurs in about 90 minute cycles, getting Recurs in about 90 minute cycles, getting
more frequent towards awakeningmore frequent towards awakening REM periods become longer as night REM periods become longer as night
progresses. progresses. REM disorders include sleepwalking / REM disorders include sleepwalking /
talking / night terrorstalking / night terrors
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““Core Sleep” Core Sleep” ““Core Sleep” Core Sleep”
Horne: first three SWS cycles with Horne: first three SWS cycles with their REM periods their REM periods
"optional" sleep the rest of the night: "optional" sleep the rest of the night: more REM, less SWS more REM, less SWS
Core sleep: about 5 hours for most Core sleep: about 5 hours for most personspersons
Only core sleep made up.Only core sleep made up.
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““Sleepiness”Sleepiness”““Sleepiness”Sleepiness”
2 components: core versus optional2 components: core versus optional missing core sleep (physiologic) -- missing core sleep (physiologic) --
disrupts physiologic systems disrupts physiologic systems missing optional sleep missing optional sleep
(psychological) -- mostly (psychological) -- mostly psychological / mood effectspsychological / mood effects
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Excess Sleepiness in Shift Excess Sleepiness in Shift WorkersWorkers
Up to 36% of rotating-shift workers experience ES.
Up to 45% of night-shift workers experience ES.
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Circadian disruptionCircadian disruptionCircadian disruptionCircadian disruption Day /awake and night / sleep are the Day /awake and night / sleep are the
normal human condition. normal human condition. When switching to a day / sleep and When switching to a day / sleep and
night / awake, various physiologic night / awake, various physiologic cycles become desynchronizedcycles become desynchronized
Hospitalization with loss of ‘Zeitgibers”Hospitalization with loss of ‘Zeitgibers” Re-synchronization at different ratesRe-synchronization at different rates Generally, all systems can shift 1 hr Generally, all systems can shift 1 hr
per day. per day.
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Adverse Health effects of Adverse Health effects of shiftworkshiftwork
Breast Cancer, Endometrial Cancer : increased Breast Cancer, Endometrial Cancer : increased in women who are not exposed to enough in women who are not exposed to enough darkness; mechanism unclear; proposed darkness; mechanism unclear; proposed mechanism is melatonin deficiency.mechanism is melatonin deficiency.
Prostate Cancer: increased most in rotating Prostate Cancer: increased most in rotating shift workers when compared to fixed-night shift workers when compared to fixed-night shift-workers, who have an extremely minimal shift-workers, who have an extremely minimal risk. risk.
Peptic Ulcer Disease /Obesity / Cardiovascular Peptic Ulcer Disease /Obesity / Cardiovascular DiseaseDisease
Pregnancy Issues: night work and high work Pregnancy Issues: night work and high work load increase the risk of spontaneous abortionload increase the risk of spontaneous abortion
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Inter-relationships are Inter-relationships are complexcomplex
Obesity, pregnancy, high fat diets Obesity, pregnancy, high fat diets and circadian rhythmand circadian rhythm
Npas2 is a key organizer of the Npas2 is a key organizer of the circadian system; if maternal diet is circadian system; if maternal diet is high fat, the fetal liver fetal histone high fat, the fetal liver fetal histone code is mal-transcribed, and leads to code is mal-transcribed, and leads to appetite and circadian disorders in appetite and circadian disorders in the offspring. the offspring.
www.bcm.edu/obgyn/index.cfm?pmidwww.bcm.edu/obgyn/index.cfm?pmid=11856=11856
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Common Circadian Rhythm Common Circadian Rhythm DisordersDisorders
Common Circadian Rhythm Common Circadian Rhythm DisordersDisorders
Jet Lag or Rapid Time Zone Change Jet Lag or Rapid Time Zone Change Syndrome:Syndrome:
Delayed Sleep Phase Syndrome Delayed Sleep Phase Syndrome (DSPS)(DSPS)
Advanced Sleep Phase Syndrome Advanced Sleep Phase Syndrome (ASPD)(ASPD)
Shift Work Sleep Disorder (SWSD)Shift Work Sleep Disorder (SWSD)
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Jet Lag / Shift workJet Lag / Shift work
Personal cycles out of synchrony with Personal cycles out of synchrony with local conditions. local conditions.
Sleepy when alertness is required; Sleepy when alertness is required; alert when sleep requiredalert when sleep required
Caused by travel across time zones, Caused by travel across time zones, shift work and sometimes by shift work and sometimes by adolesnceadolesnce
Can cause chronodysruption, since Can cause chronodysruption, since different systems re-synchronize at different systems re-synchronize at different rates. different rates.
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Zeitgibers Zeitgibers (from Gr. “Time Tellers”)
Zeitgibers Zeitgibers (from Gr. “Time Tellers”)
the physical and social clues which the physical and social clues which tell us what time it is.tell us what time it is.
Most powerful is light. Most powerful is light. Others include taste and Others include taste and smell of usual breakfast smell of usual breakfast food, going to work, food, going to work, sound of daytime activitiessound of daytime activities
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Night Owls vs. Morning LarksNight Owls vs. Morning LarksNight Owls vs. Morning LarksNight Owls vs. Morning Larks Night people = easier adjustment to shift Night people = easier adjustment to shift
workwork Tend to be phase delayed Tend to be phase delayed Day people = harder with shift change; Day people = harder with shift change;
more stable once adjustedmore stable once adjusted Tend to be more synchronized and more Tend to be more synchronized and more
resistant to re-settingresistant to re-setting Residency survey: EP s have more night Residency survey: EP s have more night
types than normal populationstypes than normal populations
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Delayed Sleep Phase Delayed Sleep Phase Syndrome (DSPS)Syndrome (DSPS)
A disorder of sleep timing. A disorder of sleep timing. People with DSPS tend to fall asleep People with DSPS tend to fall asleep
very late very late Difficulty waking up in time for work, Difficulty waking up in time for work,
school, or social engagementsschool, or social engagements Common, perhaps normal in Common, perhaps normal in
adolescenceadolescence ““Owls”Owls”
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Advanced sleep-phase Advanced sleep-phase syndrome (ASPS)syndrome (ASPS)
ASPS persistent early evening sleep onset ASPS persistent early evening sleep onset time (between 6:00 pm and 9:00 pm) and time (between 6:00 pm and 9:00 pm) and spontaneous early morning wake-up time spontaneous early morning wake-up time (between 3:00 am and 5:00 am).(between 3:00 am and 5:00 am).
Variably associated with inadquate sleep.Variably associated with inadquate sleep. Less common than DSPS Less common than DSPS Associated with extreme age and Associated with extreme age and
depression.depression. ““Larks”Larks”
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Non 24-Hour Sleep Wake Non 24-Hour Sleep Wake Disorder (N24HS/W disorder): Disorder (N24HS/W disorder):
Innate 23-25 hr cycles constantly Innate 23-25 hr cycles constantly reset by zeitgibersreset by zeitgibers
Normal sleep pattern but inate cylce Normal sleep pattern but inate cylce is neither firm nor maintained. is neither firm nor maintained.
Struggles with “Free cycling” Struggles with “Free cycling” Inconsistent Inconsistent insomniainsomnia that occurs at that occurs at
different times each night. different times each night.
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Definitions Definitions for for
Emergency Emergency MedicineMedicine
Definitions Definitions for for
Emergency Emergency MedicineMedicine
On - call On - call On dutyOn duty Sleep deprivationSleep deprivation ChronodisruptionChronodisruption
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On Call versus On DutyOn Call versus On DutyOn Call versus On DutyOn Call versus On Duty
““On call”: night work between working On call”: night work between working days = pure sleep deprivationdays = pure sleep deprivation
Possibility of sleep while on callPossibility of sleep while on call Usually does not cause circadian rhythm Usually does not cause circadian rhythm
disruptions -- body cycles remain in phasedisruptions -- body cycles remain in phase ““On duty” implies expected time of usual On duty” implies expected time of usual
type of worktype of work Isolated night shifts “on duty” (less than Isolated night shifts “on duty” (less than
once per week) physiologically function as once per week) physiologically function as ‘on call’‘on call’
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Sleep deprivation Sleep deprivation Sleep deprivation Sleep deprivation
loss of "optional sleep" (sleeping less loss of "optional sleep" (sleeping less than one's habit) causes drowsiness, than one's habit) causes drowsiness, no other serious effects no other serious effects
"core sleep" deprivation (less than 5 "core sleep" deprivation (less than 5 hours of slow wave sleep)hours of slow wave sleep)
Sleep deprivation causes both Sleep deprivation causes both physiologic and psychological ill physiologic and psychological ill effectseffects
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Shift work prevalenceShift work prevalenceShift work prevalenceShift work prevalence
Not a new phenomenon, but now Not a new phenomenon, but now vastly more frequent. vastly more frequent.
25% of American workers are shift 25% of American workers are shift workers at some point in their lives.workers at some point in their lives.
Invention of the light bulb: 1883Invention of the light bulb: 1883
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Shift work definitionShift work definitionShift work definitionShift work definition
Work a defined period of time, then Work a defined period of time, then off for a periodoff for a period
Working time can be at any time of Working time can be at any time of the 24-hr daythe 24-hr day
Fixed shifts -- working the same time Fixed shifts -- working the same time every dayevery day
Rotating shifts -- working time of day Rotating shifts -- working time of day changes from time to timechanges from time to time
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Shift lengthShift lengthShift lengthShift length
length of shift: most common is 8 length of shift: most common is 8 hourshours
others are 10, 12 and 6 hoursothers are 10, 12 and 6 hours more mistakes made in the last 4 more mistakes made in the last 4
hours of a 12 hour shift than in the hours of a 12 hour shift than in the first 8 hoursfirst 8 hours
Shift changes become more difficult Shift changes become more difficult after age 40after age 40
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 3838
Serious adverse health Serious adverse health consequences of shift workconsequences of shift work
Serious adverse health Serious adverse health consequences of shift workconsequences of shift work
20% decrease in life span20% decrease in life span 62% sleep disturbance62% sleep disturbance higher rate of accidents on the jobhigher rate of accidents on the job high risks of fatal commuting high risks of fatal commuting
accidentsaccidents 800% risk of ulcers 800% risk of ulcers 1500% incidence of depression and 1500% incidence of depression and
mood swings mood swings
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 3939
Shift work is also linked to: Shift work is also linked to: Shift work is also linked to: Shift work is also linked to:
drug and alcohol abusedrug and alcohol abuse altered immune responsealtered immune response infertility in womeninfertility in women high divorce rate.high divorce rate.
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 4040
Cardiovascular effects of Cardiovascular effects of shift work is ...shift work is ...
Cardiovascular effects of Cardiovascular effects of shift work is ...shift work is ...
linked to chronic hypertensionlinked to chronic hypertension increased cardiovascular mortality increased cardiovascular mortality (risk worse than smoking a pack of (risk worse than smoking a pack of
cigarettes per day)cigarettes per day) risk for dysrhythmias (PVC, MAT, risk for dysrhythmias (PVC, MAT,
SVT)SVT) risk of sinus arrest (up to 12 sec in risk of sinus arrest (up to 12 sec in
one study)one study)
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Tolerance to shift workTolerance to shift workTolerance to shift workTolerance to shift work Better in younger persons (under 40, or Better in younger persons (under 40, or
pre-menopausal)pre-menopausal) Better in childless personsBetter in childless persons Better in natural owls than natural larks Better in natural owls than natural larks 20% of people have no trouble 20% of people have no trouble
changing shifts, changing shifts, 60% have moderate hardship, and 60% have moderate hardship, and 20% have extreme difficulty. 20% have extreme difficulty.
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 4242
Shift work patternsShift work patternsShift work patternsShift work patterns most work has been done on 8 hour most work has been done on 8 hour
shiftsshifts 12 hour shifts no longer permitted in 12 hour shifts no longer permitted in
most industriesmost industries rotating shiftsrotating shifts isolated shiftsisolated shifts random shiftsrandom shifts
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 4343
Shift schedulesShift schedulesShift schedulesShift schedules
Optimum: days only; in synchronous Optimum: days only; in synchronous with your own best working timewith your own best working time
Next best: same shift every day, Next best: same shift every day, even if not most suited to your even if not most suited to your optimal time; or isolated nightsoptimal time; or isolated nights
Worst: randomly rotating shiftsWorst: randomly rotating shifts
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 4444
Rotation patterns: Swing Rotation patterns: Swing shiftsshifts
Rotation patterns: Swing Rotation patterns: Swing shiftsshifts
Phase advance: one week days, one Phase advance: one week days, one week evenings, one week nightsweek evenings, one week nights
Phase retreat: (Southern Swing): one Phase retreat: (Southern Swing): one week days, one week nights, one week days, one week nights, one week eveningsweek evenings
Of the two, phase advance is more Of the two, phase advance is more physiologic and more easily toleratedphysiologic and more easily tolerated
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Randomly changingRandomly changingRandomly changingRandomly changing
almost universally condemnedalmost universally condemned forbidden by most unionsforbidden by most unions highest physiologic risk and stresshighest physiologic risk and stress practiced mostly by physicianspracticed mostly by physicians
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Isolated nightsIsolated nightsIsolated nightsIsolated nights
defined as less than one night per defined as less than one night per weekweek
equivalent to a bad night on callequivalent to a bad night on call
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Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 4949
Important!Important!Important!Important! One can adjust by 1-2 hrs. / 24, or one One can adjust by 1-2 hrs. / 24, or one
week to move forward by one (8 hr) shiftweek to move forward by one (8 hr) shift Therefore, maintain the same schedule Therefore, maintain the same schedule
when not workingwhen not working most permanent night workers switch to most permanent night workers switch to
day-life when not at work and reap the day-life when not at work and reap the same ill effects as random-shift changerssame ill effects as random-shift changers
Optimal: one month or more between Optimal: one month or more between changeschanges
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What about physicians?What about physicians?What about physicians?What about physicians?
MD = Maximum DenialMD = Maximum Denial Socialized to ignore their own needsSocialized to ignore their own needs Trained to be ‘tough’Trained to be ‘tough’ poor role modelspoor role models
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Cardiovascular effects in Cardiovascular effects in physicians: physicians:
Cardiovascular effects in Cardiovascular effects in physicians: physicians:
palpitations and dysrhythmias palpitations and dysrhythmias Brodsky M, Wu D, Denes P, Kanakis C, Brodsky M, Wu D, Denes P, Kanakis C,
Rosen KM: Arrhythmias documented Rosen KM: Arrhythmias documented by 24 hour continuous by 24 hour continuous electrocardiographic monitoring in 50 electrocardiographic monitoring in 50 male medical students without male medical students without apparent heart disease. Am J apparent heart disease. Am J Cardiology 1977;39:390-395Cardiology 1977;39:390-395
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Cardiovascular effectsCardiovascular effectsCardiovascular effectsCardiovascular effects
sinus arrest with syncope in sinus arrest with syncope in residentsresidents
Guilleminault C, Pool P, Motta J, Gillis Guilleminault C, Pool P, Motta J, Gillis AM: Sinus arrest during REM sleep in AM: Sinus arrest during REM sleep in young adults. NEJM: 1984;311:1006-young adults. NEJM: 1984;311:1006-1010
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More studiesMore studiesMore studiesMore studies Physicians aren’t immune to poor Physicians aren’t immune to poor
health effects of shift workhealth effects of shift work Åkerstedt T, Knutsson A, Alfredsson L, Theorell T: Åkerstedt T, Knutsson A, Alfredsson L, Theorell T:
Shift work and cardiovascular disease. J Work Shift work and cardiovascular disease. J Work Environ Health: 1984; 10:409-414Environ Health: 1984; 10:409-414
Åkerstedt T. Psychological and psychophysiological Åkerstedt T. Psychological and psychophysiological effects of shift work. Scand J Work Environ Health. effects of shift work. Scand J Work Environ Health. 1990;16(suppl 1):67-73 1990;16(suppl 1):67-73
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 5555
Performance of physiciansPerformance of physiciansPerformance of physiciansPerformance of physicians
Poor performance with micro-sleeps (non-Poor performance with micro-sleeps (non-restorative) during rote tasksrestorative) during rote tasks
Documented micro and mini-sleeps during Documented micro and mini-sleeps during drive home even in those who did not drive home even in those who did not think they had sleptthink they had slept
Åkerstedt et al: Physicians during and following Åkerstedt et al: Physicians during and following night call duty--41 hour ambulatory recording of night call duty--41 hour ambulatory recording of sleep. Electroencephalography & Clinical sleep. Electroencephalography & Clinical Neurophysiology: 1990; (76) 193-196Neurophysiology: 1990; (76) 193-196
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Physician learningPhysician learningPhysician learningPhysician learning
Decreased performance, learning of Decreased performance, learning of deleterious habits and physiologic deleterious habits and physiologic harm.harm.
Asken MJ, Raham DC: Resident Asken MJ, Raham DC: Resident Performance and Sleep Deprivation: Performance and Sleep Deprivation: A Review. J. Med Educ 1983;58:382-A Review. J. Med Educ 1983;58:382-388388
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 5757
Overall performance Overall performance Overall performance Overall performance
Found that shift work affected rote Found that shift work affected rote tasks and the highest intellectual tasks tasks and the highest intellectual tasks equally as much; moderately equally as much; moderately challenging but well known tasks challenging but well known tasks suffered least. Implication for suffered least. Implication for physicians: we make more mistakes physicians: we make more mistakes on the more serious caseson the more serious cases
Tilley et al The sleep and performance of Tilley et al The sleep and performance of shift workers. Human Factors, 1982; 24: shift workers. Human Factors, 1982; 24: 624-41624-41
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 5858
Exercise tolerance Exercise tolerance Exercise tolerance Exercise tolerance
Sleep deprivation had little effect on Sleep deprivation had little effect on acute exercise tolerance in normal acute exercise tolerance in normal personspersons
Chen H: Effects of 30-h sleep loss on Chen H: Effects of 30-h sleep loss on cardiorespiratory functions at rest and in cardiorespiratory functions at rest and in exercise. Med Sci Sports and Exerc: 1991; exercise. Med Sci Sports and Exerc: 1991; 23(2):193-19823(2):193-198
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 5959
Shift lengthShift lengthShift lengthShift length Used temperature as a marker for Used temperature as a marker for
slowing of physiologic activitiesslowing of physiologic activities Concluded that 12 hour shifts lead to Concluded that 12 hour shifts lead to
increased mistakes poorer per-hour increased mistakes poorer per-hour productivity productivity
Daniel J, Potasova A; Oral temperature Daniel J, Potasova A; Oral temperature and performance in 8 h and 12 h and performance in 8 h and 12 h shifts . Ergonomics 32(7):689-96 , 1989 shifts . Ergonomics 32(7):689-96 , 1989 Jul.Jul.
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 6060
Strategies to improve health Strategies to improve health for shift workersfor shift workers
Strategies to improve health Strategies to improve health for shift workersfor shift workers
sleep hygiene sleep hygiene napping at worknapping at work shift rotation patternsshift rotation patterns food & exercisefood & exercise social lifesocial life
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If you must be a shift If you must be a shift worker:worker:
If you must be a shift If you must be a shift worker:worker:
Learn how to sleep wellLearn how to sleep well Learn how to change your circadian Learn how to change your circadian
rhythms smoothlyrhythms smoothly Use circadian principles to make your Use circadian principles to make your
work and home life betterwork and home life better Educate your schedule-makerEducate your schedule-maker Educate and enlist your familyEducate and enlist your family
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Living the Strategic LifeLiving the Strategic Life
Avoid vigorous exercise at least 4 Avoid vigorous exercise at least 4 hours prior to bedtime (Regular hours prior to bedtime (Regular exercise is recommended.)exercise is recommended.)
Avoid cigarettes, alcohol, and Avoid cigarettes, alcohol, and caffeine 4-6 hours prior to bedtimecaffeine 4-6 hours prior to bedtime
Avoiding large meals and excessive Avoiding large meals and excessive fluids just before bedtimefluids just before bedtime
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Light therapy: Light therapy:
Timing of lightTiming of light Minimum of 30-60 minutes not long after Minimum of 30-60 minutes not long after
wakening to promote adaptation and wakening to promote adaptation and wakefullnesswakefullness
Re-synchronising ASPS light in the early Re-synchronising ASPS light in the early evening and nighttime hours delays the evening and nighttime hours delays the cyclecycle
DSPS light therapy in the early morning DSPS light therapy in the early morning hours stimulates morning alertness and an hours stimulates morning alertness and an earlier bedtime. earlier bedtime.
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Environmental controlEnvironmental control
Light – adequate at work (6,000-Light – adequate at work (6,000-7,000 Lux) 7,000 Lux)
Dark – during sleep time (less than Dark – during sleep time (less than full moon) (consider eye shades)full moon) (consider eye shades)
Noise – shut out during sleep. Isolate Noise – shut out during sleep. Isolate sleep room, use earplugssleep room, use earplugs
Room temperature – warm sleepers Room temperature – warm sleepers vs cool sleepersvs cool sleepers
Exercise, DietExercise, Diet
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Sleep HygieneSleep HygieneSleep HygieneSleep Hygiene
Temperature: between 22 - 24 CTemperature: between 22 - 24 C Bedroom: Condition yourself that Bed Bedroom: Condition yourself that Bed
= Sleep time= Sleep time Ritual: helps to create a ‘stimulus-Ritual: helps to create a ‘stimulus-
response’ conditioning response’ conditioning Keep sleep time sacred, and Keep sleep time sacred, and
minimize care-giving responsibilities minimize care-giving responsibilities during that time.during that time.
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Diet Diet Diet Diet
troubled by early awakening? => try troubled by early awakening? => try bedtime snack. bedtime snack.
Milk products seem to improve sleep. Milk products seem to improve sleep. Alcohol: a single drink can help tense Alcohol: a single drink can help tense
people relax, but alcohol actually people relax, but alcohol actually alters sleep structure by postponing alters sleep structure by postponing REMREM
Great care to eat appropriately during Great care to eat appropriately during the working / waking timethe working / waking time
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 6868
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 6969
Exercise Exercise Exercise Exercise
Athletes: get more delta Athletes: get more delta (SWS, restorative) sleep. (SWS, restorative) sleep.
Time of day important: Time of day important: pm exercise has more pm exercise has more effect.effect.
Exercise should be Exercise should be completed more than one completed more than one hour before sleep timehour before sleep time
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 7070
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 7171
Light – most important for Light – most important for humanshumans
Light – most important for Light – most important for humanshumans
intensity is important: 7,000 Luxintensity is important: 7,000 Lux about the same as a heavily overcast dayabout the same as a heavily overcast day most indoor lighting is inadequatemost indoor lighting is inadequate new ‘energy saving’ fixtures are even more new ‘energy saving’ fixtures are even more
inadequateinadequate implication to hospital administration: high implication to hospital administration: high
intensity lights over physicians / nurses intensity lights over physicians / nurses working areas improves productivity and working areas improves productivity and minimizes mistakes.minimizes mistakes.
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Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 7373
Timing of light pulses is Timing of light pulses is importantimportant
Timing of light pulses is Timing of light pulses is importantimportant
2-3 hours of high intensity light 2-3 hours of high intensity light within one hour of awakeningwithin one hour of awakening
implication for shift workers: either implication for shift workers: either go outside while the sun is still up go outside while the sun is still up before going to work the night shift, before going to work the night shift, or buy and use a high intensity light or buy and use a high intensity light at homeat home
Fluorescents in windows.Fluorescents in windows.
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 7474
Drugs and Pharmacology Drugs and Pharmacology Drugs and Pharmacology Drugs and Pharmacology
Drugs to sleep or to wake or re-Drugs to sleep or to wake or re-synchronizesynchronize
MDs: temptation and access to non-MDs: temptation and access to non-legal drug uselegal drug use
health care shift workers are at high health care shift workers are at high risk for drug addictionrisk for drug addiction
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 7575
MelatoninMelatonin
Melatonin is a re-synchronizerMelatonin is a re-synchronizer used in the treatment of circadian used in the treatment of circadian
rhythm sleep disorder especially in rhythm sleep disorder especially in blind personsblind persons
OTC “diet supplement” dosing OTC “diet supplement” dosing guidelines not established. My use: guidelines not established. My use: 6-6-3-36-6-3-3
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 7676
Melatonin Melatonin Melatonin Melatonin
3-6 mg, taken one hour prior to 3-6 mg, taken one hour prior to desired (new) sleep timedesired (new) sleep time
Diminished (genetically?) in aging. Diminished (genetically?) in aging. Full effects of chronic exposure not Full effects of chronic exposure not
yet known. yet known. Not FDA regulated, but seems to be Not FDA regulated, but seems to be
extremely safe for brief use as in extremely safe for brief use as in phase adjustment. phase adjustment.
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 7777
Melatonin stimulant Melatonin stimulant RamelteonRamelteon ((RozeremRozerem) )
Rx only. Rx only. stimulates melatonin releasestimulates melatonin release Ramelteon promotes the onset of Ramelteon promotes the onset of
sleep and helps normalize circadian sleep and helps normalize circadian rhythm disorders. rhythm disorders.
Ramelteon is approved by the Ramelteon is approved by the Food and Drug AdministrationFood and Drug Administration (FDA) (FDA) for insomnia characterized by for insomnia characterized by difficulty falling asleep.difficulty falling asleep.
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 7878
Hypnotics: BenzodiazipinesHypnotics: Benzodiazipines
Benzodiazepines: short acting for Benzodiazepines: short acting for sleep onset or napping. Triazolam sleep onset or napping. Triazolam (Halcion) (Halcion)
Medium or long-acting: for sleep Medium or long-acting: for sleep maintenance. estazolam [ProSom] maintenance. estazolam [ProSom] quazepam [Doral]quazepam [Doral]
Possibility of rebound insomniaPossibility of rebound insomnia
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 7979
Benzodiazepines side Benzodiazepines side effectseffects
Benzodiazepines side Benzodiazepines side effectseffects
can disrupt sleep architecturecan disrupt sleep architecture may have residual sedative effects may have residual sedative effects
lasting into the next working periodlasting into the next working period many are fat soluble and will leach many are fat soluble and will leach
out over many daysout over many days illegal in some working environmentsillegal in some working environments
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 8080
Non-benzodiazepine Non-benzodiazepine hypnoticshypnotics
Less effect on sleep architecture Less effect on sleep architecture than benzos, less rebound insomnia than benzos, less rebound insomnia
Zolpidem (Ambien) moderate to long Zolpidem (Ambien) moderate to long actingacting
Eszopicline (Lunesta) moderate Eszopicline (Lunesta) moderate duragionduragion
Zaleplon (Sonata) short actingZaleplon (Sonata) short acting
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 8181
OTC hypnoticsOTC hypnotics
Benadryl – 25-50mg. TachyphylaxisBenadryl – 25-50mg. Tachyphylaxis Alcohol – disrupts sleep architecture Alcohol – disrupts sleep architecture Herbs: hops, valerian, passion flower Herbs: hops, valerian, passion flower Marijuana – legal issues, prolonged Marijuana – legal issues, prolonged
effectseffects
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 8282
Diphenhydramine / sedative Diphenhydramine / sedative antihistaminesantihistamines
Diphenhydramine / sedative Diphenhydramine / sedative antihistaminesantihistamines
sedative antihistamines help induce sedative antihistamines help induce sleep, and in some, help maintain sleepsleep, and in some, help maintain sleep
effect on sleep architecture is minimaleffect on sleep architecture is minimal tachyphylaxis: effects wane within daystachyphylaxis: effects wane within days may produce prolonged sedation, may produce prolonged sedation,
interfering with performance and interfering with performance and maintenance of new schedule when not maintenance of new schedule when not at workat work
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 8383
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AlcoholAlcoholAlcoholAlcohol
disrupts sleep architecturedisrupts sleep architecture delays REM sleepdelays REM sleep variable effect on sleep latencyvariable effect on sleep latency recommendation for shift workers: recommendation for shift workers:
finish your alcohol more than one finish your alcohol more than one hour before scheduled sleep timehour before scheduled sleep time
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 8585
Cheat Sleep: stimulants Cheat Sleep: stimulants
OTC: primarily caffeineOTC: primarily caffeine Illegal: Cocaine, “Speed” and various Illegal: Cocaine, “Speed” and various
“uppers”“uppers” Legal: Legal:
• amphetamines and amphetamine –like amphetamines and amphetamine –like drugs drugs
• Ampakines and their sucessorsAmpakines and their sucessors
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 8686
Amphetamines Amphetamines
methylphenidate (Ritalin, Metadate, methylphenidate (Ritalin, Metadate, Concerta)Concerta)
dextroamphetamine Plus dextroamphetamine Plus amphetamine (Adderall)amphetamine (Adderall)
DextroamphetamineDextroamphetamine (Dexedrine) (Dexedrine) lisdexamfetamine dimesylate – lisdexamfetamine dimesylate –
metabolized to methamphetamine metabolized to methamphetamine ((Vyvanse) Vyvanse)
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 8787
Ampakines and their Ampakines and their successorssuccessors
Modafinil (Modafinil (ProvigilProvigil, Alertec, Modavigil, , Alertec, Modavigil, Modalert, Modiodal, Modafinilo, Carim, Modalert, Modiodal, Modafinilo, Carim, Vigia) Vigia)
analeptic drug manufactured by Cephalon, analeptic drug manufactured by Cephalon, and is approved by the FDA for shift and is approved by the FDA for shift workersworkers
Armodafinil (Nuvigil) is the active (−)-(Armodafinil (Nuvigil) is the active (−)-(RR)-)-enantiomer of the racemic drug modafinil enantiomer of the racemic drug modafinil
Side effects include potentially cognitive Side effects include potentially cognitive enhancement, and loss of effect of BCPsenhancement, and loss of effect of BCPs
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 8888
CaffeineCaffeineCaffeineCaffeine
harmless in small dosesharmless in small doses taking caffeine to get through the taking caffeine to get through the
night shift may interfere with day night shift may interfere with day sleepsleep
careful with timing of caffeine intakecareful with timing of caffeine intake
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 8989
Optimal phase adjustment Optimal phase adjustment strategiesstrategies
Optimal phase adjustment Optimal phase adjustment strategiesstrategies
bright light early in waking timebright light early in waking time significant exercise later in waking period significant exercise later in waking period optimize sleeping conditions: aluminum-optimize sleeping conditions: aluminum-
foil on the windows, ear plugs, eye foil on the windows, ear plugs, eye shades, fanshades, fan
stay on the same schedule without stay on the same schedule without varying by more than an hour as long as varying by more than an hour as long as you canyou can
Consider Melatonin.Consider Melatonin.
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 9090
SummarySummarySummarySummary
American society is more 24 / 7American society is more 24 / 7 EM always 24 / 7EM always 24 / 7 Use circadian principles to improve Use circadian principles to improve
your well being and prolong your your well being and prolong your professional life and your personal professional life and your personal lifelife
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 9191
ResourcesResources
American Academy of Sleep MedicineAmerican Academy of Sleep MedicineOne Westbrook Corporate Center, One Westbrook Corporate Center, Suite 920Suite 920Westchester, IL 60154Westchester, IL 60154(708) 492-0930(708) 492-0930
National Sleep FoundationNational Sleep Foundation1522 K Street, NW, Suite 5001522 K Street, NW, Suite 500Washington, DC 20005Washington, DC 20005
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 9292
Enhancing adaptionEnhancing adaptionEnhancing adaptionEnhancing adaption
Rotating shiftwork schedules: can we Rotating shiftwork schedules: can we enhance physician adaptation to enhance physician adaptation to night shifts?night shifts?Smith-Coggins R , Rosekind MR , Smith-Coggins R , Rosekind MR , Buccino KR , Dinges DF , Moser RP Buccino KR , Dinges DF , Moser RP Acad Emerg Med 1997 Acad Emerg Med 1997 Oct;4(10):951-61 Oct;4(10):951-61
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 9393
Best single reference Best single reference Best single reference Best single reference
"Why we Sleep" by James Horne. "Why we Sleep" by James Horne. Published by Oxford University Published by Oxford University Press Walton St Oxford OX2 6DP Press Walton St Oxford OX2 6DP 19881988
a classic overall referencea classic overall reference
Circadian Rhythms and Shift WorkCircadian Rhythms and Shift Work 9494
Web LinksWeb Links Northwestern University, Center for Sleep Northwestern University, Center for Sleep
& Circadian Biology, & Circadian Biology, About Circadian RhythmsAbout Circadian Rhythms
National Sleep Foundation, National Sleep Foundation, Strategies for Shift WorkersStrategies for Shift Workers National Sleep Foundation, National Sleep Foundation, Sleep and the TravelerSleep and the Traveler National Institute of Mental HealthNational Institute of Mental Health, ,
How Biological Clocks WorkHow Biological Clocks Work Sleepnet.comSleepnet.com