P3 - E.P - Biological Rhythms - Czeisler Flashcards
Biological Rhythms definition
Rhythms that govern much of our Psychological Functioning
* Most Important = Circadian Rhythms, a Rhythm that repeats approximately every 24hrs
Green Study (1994)
- estimates there are ~100 diff. Circadian Rhythms in mammals
- E.g. Sleeping, Waking, Body Temperature, Urine Flow, Digestion, Blood Pressure, Hormone Release etc.
Endogenous vs Exogenus
ENDO - Naturally Occuring
EXO - Dependancy on External Cues
Michael Siffre Study (cave)
- Portrayed that Circadian Rhythms are Endogenus
- However, the body uses cues both from its own internal processes & from the environment (e.g. time on clock, light-dark cycle, meal times) to keep these various Rythms in check
- Challenged wherer Endogenous or Exogenous factors inform our Circadian Rhythms
- We can entrain to a new system, but need help from zeitgebers to adjust
He spent time in a cave and maintained a regular cycle
Temperature & Sleep example of Circadian Rhythms
- Body Temperature is highest during the Afternoon & early evening & lowest in the very early morning for example
- We tend to fall asleep as our body temperature falls, & find it harder to sleep as our body temperature rises again
- Also applies to Hormones, Mood etc.
Disruption of Bodily Rhythms
Zeitgebers = Time Indicators change dramatically, our internal clocks are not able to adjust fast enough & our Physiological processas (such as hunger & sleep - wake cycle) become desynchronised from the outside world
* e.g. Jetlag
Czeisler et al.
IN RELATION TO ZEITGABERS
Bodies respond to Zeitgebers rather than ‘Body Clock’ to overcome feelings of jet lag
Phase Advances VS Phase Delayed
Phase Advanced - East > West
Phase Delayed - West > East (far easier for our body clocks to resynhronise
Impact of Shift Work (Irregular Work Hours)
- Produces similar desynchronisation of Body rhythms & Zeitgebers to Jet Lag
- E.g. Police, Nursing, Leisure Industry, some Industrial Work
Causes - Sleep Deprevation (& other sleep problems)
- Increased Susceptability to minor illnesses
- More likely to have Bad Diet &/or excess of Caffine
- Recent Research suggests Shift work is Carconogenic
Increases risk of Cancer
Melatonin
- The Sleep Hormone
- Melatonin Secretion Starts at 21:00 (9;00pm), Ends 7:30
Endogenous Pacemaker
BIOLOGICAL Internal Clock
* Something inside us that increases ability to keep the time
Exogenous Zeitgebers
Cue from the outside world that Entrain internal body clocks to match the environment
* Light is believed to be the dominant Zeitgeber
Sleep-Wake Cycle
We have a Circadian Rhythm for Sleeping & Waking, regardless of
Entrainment
Endogenous Pacemakers become Syncronysed with Zeitgebers
Ralph (2011)
- Hamsters with 20hr sleep rate Cycle
- Control group of normal 24hr Hamsters
- ~
Key Research
Examples of Night Work
- Miners
- Emergency Services
* Hospitals
* Police
* Fire Service
* Ambulance - Fast Food
- Support Centres
- 24hr Shops
- Hotel
- Factory Workers
- Care Workers
Effects of Shift Work
- Hampers Sleep
- Depression
- Hampers Heart Health
- Gastrointestinal Problems
- Increased Diabetes Risk
Experiment 1 - Questionnaire
Quasi Experiment
85 Male rotating shift workers
* Falling Asleep at Work
* Adjustment takes 2-4 days
* Insomnia
* 26% never adjust to New Shift
68 Male non-rotating shift
* Better Concentration
* Fewe Sleep Problems
* Fewer Digestive Systems
Experiment 2 - Field - IV
IV
* 21 day, NEW Shift Change pattern
* Phase Delay direction
* E.G. 11pm start, 5am start, 10am start, 3pm start. CLOCKWISE (52 of the original 85 sample)
OR
- Stay on OLD 7 Day Shift Change pattern
- Phase Advance direction
- 11pm start, 7pm start, 1pm start, 6am start. ANTI-CLOCKWISE (33 of the original 85 sample)
Experiment 2 - Field - DV
Satisfaction and Health questionnaire scores 3 and 6 months later
Reasons Night Work is in Demand
- To meet Demand for Factory or Delivery Products
- Night Shifts pay more, howeverno legal differene in Minimum Pay
CZEISLER - Sampling Bias
HIGHTENS
* Sample from Utah - low Population Validity
* Androcentric
* All worked at same mine
* Some Workers had been working for 10 years prior to the research
* Small Sample Size
* Limited Generalisability
LOWERS
Wide Age Range
* Group 1 = 19-68
* Control Group 19-56
*
CZEISLER - Ethnocentrism
- Utah, USA - ruiles and regulations
- Cannot be applied to other cultures
- Great salt lake minerals
CZEISLER - Usefulness
- There are Real Life Applications
- Reduce Health Problems in shift work through Carcadian Rythm
- Understand how it effects People
- Change Shift Patterns
- Increased Productivity and Production
CZEISLER - Reliability
- Test-retest Questionnaire x2 3 months and then 6 months
- Less Reliability due to Presentation
- Androcentrism also decreases
CZEISLER - Validity
- Presentation in Part 2 - external factors could influence
- Ecologically valid - field experiments
- Used Actual Jobs and Job Rotations
- Internal lowered not controlled environment
- Population validity = only shift pattern workers not universal
- Workers in comparanle jobs
Power Naps
- Recommended only for Night Shifts
- 20 - 45 Min Restorative Nap
- Essential for maintaining Vigilance and Alertness during the Night
Drugs to promote Sleep, Wakefulness and Adaptation
MELATONIN - Hormone, which is part of a Circadian Rhythm - released with darkness Zeitgebers - promotes Sleepiness
MELATONIN PILLS - can be bought without a prescription to help sleep during the day, and help align the circadian rhythm to work at Night
HYPNOTICS (general term) - Sleep Inducing Drugs, used to lengthen daytime sleep after Night Shifts
Power Naps + & -
- A qualitative study in Canada showed of critical care nurses showed that 10/13 who regularly napped during their breaks self-reported many benefits such as* improved mood, decision making and vigilance*.
- Innapropriate Environments and/or Facilities, as well as the Perceptions of Colleagues and Managers
- People may react differently to napping (come may still feel very tired/unmotivated)
Drugs + & -
- Daytime Sleepiness
- Headaches
- Difficult to Access in UK w/out Perscription
Long Term use of Stimulants are Highly Addictive and can cause Side Effects including:
* Irregular feelings of Hostility
* Paranoia
* Increased Body Temperature
* Irregular Heartbeat
Czeisler Application - help influence the design of work schedules
APFC - Investigated the effect of rotating shift patterns on miners’ health. Stage 1 was a questionnare on wor productivity, job satisfaction health & wellbeing given out to both rotating & non-rotating shift miners.
* Found higher number of health problems reported in the rotating shift workers, higher insomnia, obesity, lower job satisfaction. Rot reported it took up average of 3-4 to become syncronised (working w/ their circadian rythms), changing shifts every 7 days.
___
Stage 2 involved 85 miners: field experement, group that stayed in 7 day phase advance shift (33 miners) & a group went on a 21 day phase delay shift pattern (52 miners), then after 6 months, questionnaires retaken.
* Job satisfaction increased & complaints about job down by 90%, phase delay & longer periods to adjust are preffered & the company reported miners became more productive after the study.
Czeisler - how it could imfluence the design of work schedules
We could implement Czeisler’s results in giving workers as long as possible on shift pattern. Czeisler’s participants reported that they struggled in the first days of 7 day phase delay
make all work patterns go in phase delay direction (clockwise); 1 month they may start at 2pm, then next month 6pm, then 10pm, then 12pm etc. to entrain your circdian rythms; easier for your Endogenous Zeitgabers to keep up.
Ambulances, pilots, police, overnight construction workers, truck drivers could benifit fom these techniques.
Social Sensitivity
Research that might create: Stereotype, Stigma, Discrimination, Prejudice
* Buisness owners who make ppl work unhealth jobs
* Stigmas/Stereotypes for shift workers; stuck in an unhealthy job, so presumed unhealthy if they once worked a shift job
* Michael Siffre - employers can use the information to manipulate the workers into working worse shift hours; shows people can adapt to
* If shift workers are aware of the health problems, the research may teach you to make healthier choices & thus avoid many negative effects of shift work
* Ultimately justified, as there are now laws against unhealthy shift/work patterns to protect workers from the consequences; can stop the issue
