Intro to Biological rhythms and Sleep (PSYA3)

Objectives Describe 3 types of Biological Rhythms and give examples. Explain how Endogenous pacemakers and Exogenous Zeitgebers control the sleep-wake cycle Evaluate (using A.I.Ds) the role or Eps and Ez into the control of the circadian rhythms.

 A biorhythm is a pattern of physiological or psychological processes which repeats itself over a specified period of time. 1.Write down as many biological rhythms as you can think of. 2.Are these all the same? 3.If not what differences are there between the different types of rhythms?

 There are five different types of biorhythm, the difference between them being the period of time that elapses before the behaviour is repeated BIOLOGICAL RHYTHMS DescriptionLength of Cycle CircadianApproximately 24 hours CircannualApproximately one year InfradianLonger than a day e.g. Monthly UltradianMore than once within a Day

The biorhythms we study in A2 Psychology are… Circadian rhythms – Repeats once every 24 hours – example? – Sleep / Wake cycle Ultradian rhythms – Repeats more than once a day – example? – 90 minute cycles of lighter and deeper sleep Infradian rhythms – Repeats less often than once a day but more than once a year. – example? – Menstrual cycle (monthly)

Are you a lark or an owl? Complete the activity sheet Why do you think people vary like this? Why is this important when you are considering theories and research? 2 The Sleep-Wake Cycle

What controls Biological Rhythms? Endogenous Pacemakers- Internal “Body Clocks” that generate biological rhythms. OR Exogenous Zeitgebers -external factors that regulate or alter biological rhythms. How could we find out if our sleep wake cycle is controlled by Eps or Ezs?

Research into Circadian Rhythms Read the info “cave man” and “Sleep Wake cycle” on pages 2 and 3. 1.What is meant by “free Running” 2. Outline the work of Michael Siffre (1975) 3. Outline the findings of Aschoff and Wever (76) and Folkard (85) 4. In pairs evaluate the research

Evaluating Research into SW cycle Research Methodology- In all studies ppts were isolated from cues that might affect their circadian rhythm but they were not isolated from artificial light. Czeisler et al (1999) altered ppts circadian rhythm using dim light! Individual differences: Cycle length varies from 13 to 65 hrs (Czeisler et al) and also morning and evening types (Duffy)

Free Running Cycle studies Key Study Michel Siffre study What research method was used? Problems with this? Evaluating research into Circadian Rhythms using the PEEL technique

Other Circadian Rhythms Core body temperature- generally lowest at 4:30 am and highest at 6:00pm. Evidence Superior recall and comprehension in12-13 year old children working in the afternoon rather than the morning (Folkard) IQ tests results are better at 7pm rather than 9am (Gupta)

IDA: The Biological and Determinist approach Suggest our sleep wake cycle patterns are fixed caused by either internal or external mechanisms. This is not always true as we do have the power to override these processes e.g. training ourselves to wake early etc. However, these are powerful e.g. a blind man had to take stimulants and sedatives to get his bio rhythm in time with rest of society (Miles 1977)

Objectives Describe 3 types of Biological Rhythms and give examples. Explain how Endogenous pacemakers and Exogenous Zeitgebers control the sleep-wake cycle Evaluate (using A.I.Ds) the role or Eps and Ez into the control of the circadian rhythms.

Cut & Paste Pacemakers & Zeitgebers Use the challenge card and the images on the sheet, to create a visual representation of the role of the endogenous pacemaker (SCN) & exogenous zeitgeber (light) for the circadian sleep-wake cycle. Explain how Endogenous pacemakers and Exogenous Zeitgebers control the sleep-wake cycle

The Biological Clock The SCN The biological clock that controls the sleep/wake cycle is located in the SCN which is part of the hypothalamus.

Exogenous Zeitgebers (external mechanism)  SCN have a nerve input directly from the retina of the eye, so they are kept informed about the zeitgebers of light and darkness.  In darkness this information is transmitted to the pineal gland which manufactures melatonin a hormone which stimulates the production of serotonin in the raphe nucleus this hormone causes reduced levels of arousal and so induces sleep.  When Light enters through the eyes it stimulates the SCN to produce an inhibiting factor (probably a protein) This inhibits the production of melatonin by the pineal gland and so maintains arousal levels – keeping you alert and awake!

Melatonin Secretion Time of Day Melatonin Level 7 am 7 pm7 am asleep

Darkness Falls Optic chiasm in eye Stimulates SCN Stimulates Pineal Gland Produces Melatonin Enhances production of Serotonin Brain Activity falls Sleep.

Evaluating the role of Endogenous pacemakers. Activity Cunning commentary sheet (Make a note of any A.I.Ds) Sackett and Korner (1993) Twins Morgan (1995) Hamsters Folkard (1996) DeCoursey (2000) Chipmunks

Objectives Describe 3 types of Biological Rhythms and give examples. Explain how Endogenous pacemakers and Exogenous Zeitgebers control the sleep-wake cycle Evaluate (using A.I.Ds) the role or Eps and Ez into the control of the circadian rhythms.

LESSON ACTIVITY & HOMEWORK Use text books, handouts to complete a poster OR mind map entitled: ‘The Biological Clock’ This should include four headings detailing: 1.It’s endogenous components 2.How it is affected by exogenous factors and what they are. 3.Research evidence to support and challenge these theories 4.Limitations, Implications & Applications of this research 5.A.I.Ds