Physiological Psychology

1. Physiological Psychology Biological Rhythms Bio Rhthyms

2. Bio Rhthyms

3. What is a bio-rhythm? Which of the following diagrams would you consider to be showing a rhythmic pattern? Bio Rhthyms

4. What is a biological rhythm? • A periodic change in the behaviour or physiology of animals and plants • (eg sleep, hibernation and migration) • People that study biological rhythms are known as ‘chronobiologists’ Bio Rhthyms

5. 1 Ultradian Rhythm (less than 24 hours) 2 Circadian Rhythm (24 hours) 3 Infradian Rhythm (1 month) 4 Circannual Rhythms (1 year) The Main Bio-Rhythms Bio Rhthyms

6. The Circadian Rhythm A daily rhythmic activity cycle, based on 24-hour intervals Bio Rhthyms

7. The Circadian Rhythm • We have evolved to fit the 24 hour clock • Even single celled organisms display a 24 hour cycle • Mammals have evolved to fit the cycle • Nocturnal v Diurnal • There are around 100 types of Circadian Cycles (Green 1994) • Most commonly known is sleep wake cycle • Although this is different in infancy Bio Rhthyms

8. Development of Circadian Rhythms in Infancy At what point would you say the infant’s rhythm becomes established? Bio Rhthyms

9. ACTIVITY • Describe your average day: • What time do you wake? How do you feel? • When do you get hungry? When do you have lunch? • When do you start to feel tired? When do you go to sleep? Bio Rhthyms

10. Bio Rhthyms

11. The Night Owl Shows “morning syndrome” i.e. awakens as day goes on … Goes to bed late – midnight or later Wakes late as possible in morning Feels ‘ill’ if has to get up at 6am Feels tired during the day due to too little sleep The Morning Lark Doesn’t show morning syndrome Tends to wake early before 7am Active soon after waking Struggles to stay up late Can fall asleep fast if goes to bed early e.g. 9pm morning or night person? Bio Rhthyms

12. Other Circadian Rhythms • Temperature regulation • Cognitive functioning • Pain tolerance • Certain illnesses are worse at different times • e.g. hay fever in the morning, or late at night • Chronotherapeutics address this Bio Rhthyms

13. Key Study: Siffre What day is it? • Spent some time in a cave • Absence of all time givers • Extended his circadian cycle to approx 27 hours • Spent 179 days in cave (but he thought 151!) • However, Lavie (2001) puts the shift at only a few minutes using careful controls Bio Rhthyms

14. The Circadian Shift Bio Rhthyms

15. Exogenous Zeitgeber Outside the body External cues (e.g. your alarm clock) Environmental stimuli (e.g. daylight, temperature change) Endogenous Pacemaker Within the body Specific bio-chemical changes (e.g. melatonin, SCN, pineal gland) But what gives us our sense of time? Bio Rhthyms

16. Suprachiasmic Nucleus (SCN) Bio Rhthyms

17. The Suprachiasmic Nucleus Bio Rhthyms

18. small cluster of cells in our hypothalamus called the: Suprachiasmatic nucleus (SCN). linked to our visual system influenced by the amount of light we detect. Endogenous Pacemakers Bio Rhthyms

19. Endogenous Pacemakers • SCN can in turn cause the • pineal gland to produce a hormone called • melatonin • This can make you feel sleepy. Bio Rhthyms

20. 24 Hours of Melatonin Secretion Ok, what conclusions would you draw from this chart. Can you explain why this happens? Bio Rhthyms

21. The general scientific test for endogenous rhythms • Place the organism into an environment devoid of all external patterns • (e.g. constant light and temperature) • Observe if the rhythmic pattern continues. • This would be in a laboratory situation where a constant environment is maintained. • Endogenous rhythms are usually coded in the organisms DNA, and hence the endogenous pattern is usually inheritable. Bio Rhthyms

22. DeCoursey et al (2000) I may look cute, but just because researchers were a bit cruel to me, you can’t use that as an evaluation! • destroyed the SCN in some chipmunks. • found that these chipmunks were much more active at night • however they were also more likely to be taken by nocturnal predators • Support for the ecological theory in sleep (more on that later) Bio Rhthyms

23. Internet Resources http://www.a-levelpsychology.co.uk/online/a2/chapter04/intex1.asp an interactive resource on sleep-wake cycle Bio Rhthyms

24. What about the following: • Watching TV late at night? • Staying indoors during the winter? • Solar eclipse? • Summer in Norway? • Flying from San Francisco to London? Bio Rhthyms

25. Disruption of Circadian Rhythms • Jet Lag (Spitzer et.al.) • Body is out of phase • You think/feel it’s a different time. • Worse travelling from the west to an eastern time zone • (e.g. Los Angeles to London) Bio Rhthyms

26. Prevention of Jet Lag Using artificial doses of melatonin can reduce the effect of jet lag Bio Rhthyms

27. Internet resources • http://www.a-levelpsychology.co.uk/online/a2/chapter04/intex2.asp • An interactive resource on jet lag Bio Rhthyms

28. Common Effects of Shift Work • Lack of communication between staff • Lack of ‘teamwork’ • Poorer concentration on duty tasks • Unsafe conditions • Stress • Shift lag Bio Rhthyms

29. Shift Lag • Mental symptoms: • Increased irritability • Overly emotional • Forgetfulness • Physical Symptoms: • Fatigue • Loss of energy • Tiredness Bio Rhthyms

30. Key Studies: Monk & Folkard (1985) • Interviewed workers who regularly changed shift • Found changing shifts was better for for: • Subjective wellbeing • Productivity Bio Rhthyms

31. Key Studies: Czeisler (1982) • Workers at a chemical plant in Utah took 16 days to adjust • Conclusion; workers should move forward in time (clockwise) • Job satisfaction increased • Productivity rose • Accident rates declined • Workers report more satisfaction in leisure time Bio Rhthyms

32. Infradian Rhythms • for more than one day • e.g. the 28 day menstrual cycle, • Tied in closely to the lunar month (the only external cue). • Evolutionary adaptation? • nocturnal predation Bio Rhthyms

33. Menstruation • Levels in female sex hormones change • Ovulation • Pre-menstrual syndrome • (changes in female sex hormones) • Menstrual synchrony • (pheromone cues) Bio Rhthyms

34. Key study: Rienberg (1967) • Studied girl in cave for 3 months • Menstrual cycle shortened to 25.7 days • Took a year to get back to her normal cycle of 27 days • (By the way, her day lengthened to 24.6 hours – support for Siffre) Bio Rhthyms

35. Bio Rhthyms

36. The Ovulation Cycle Bio Rhthyms

37. Ultradian rhythmsThese are rhythms that are shorter than a day. Such rhythms occur during sleep, but other ultradian rhythms include excretion from the kidneys and heart rate. People addicted to nicotine will show an ultradian rhythm — smoking! Bio Rhthyms

38. Ultradian rhythms in sleepElectroencephalogram (EEG) recordings have revealed that the brain is still active during sleep, but different states of awareness have distinct patterns of electrical activity associated with them in the normal individual. Wakefulness, the immediate pre-sleep stage, light sleep, deep sleep and periods of dreaming (REM sleep) can all be identified through EEG recording – all ultradian rhythms! Bio Rhthyms

39. Circannual Rhythms • Male hamsters testosterone levels change over the year • Breeding season triggered by longer days • Lesions in the SCN disrupt this • Testosterone is secreted all year! • (Rusak & Zuker 1975) Bio Rhthyms

40. Fertility and Summer • Reinberg (1967) study in 600 german schoolgirls • They tend to start their menstruation during winter months • Stable menstrual cycles occur more in summer, hence more conceptions Bio Rhthyms

41. Seasonal Affective Disorder (S.A.D.) • Lack of daylight • Increases melatonin • Fatigue • Disordered sleep patterns • Risk of depression • Treated with UV light and/or melatonin therapy. • For more info follow the link: http://hcd2.bupa.co.uk/fact_sheets/html/sad.html Bio Rhthyms