P3 - E.P - Biological Rhythms 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
- 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 out Circadian Rhythms
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
De-Synchronysed
Jet-Lag
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
