Biothythms revision 2012 worksheet - The Grange School Blogs

Circadian Rhythms•Sleep/wake cycle - controlled by SCN and light.Pineal gland produces melatonin when dark >sleep, levels reduce by morning > wake. Lightresets sleep wake cycle as day length changes.•Research - Siffre (1975) - Cave studies - freerunning- cycle persists even without light•SYNOPTIC - Humanshave choice (determ/free will)Application -chronotherapeuticsAschoff and Wever (76), Folkard et al (85) -cycle length varies in individualsA02 - Case studies, individual differences, artificialInfradian Rhythms• Female menstrual cycle regulates ovulation -hormonal regulation•Research - cycle can be subject to exogenouscues e.g pheromones - Russell et al 1980 -women living together synchronise menstrualcycle. PMS physiological and psychologicalproblem (Dalton 1964)

Infradian Rhythms• Seasonal Affective Disorder (SAD) - caused byhigher levels of melatonin in darker winter months.Link between high levels of melatonin anddepression - greater suicide rate in northernEurope.•A02 - But may just be due to disrupted circadianrhythm - go to bed earlier and get up later whendark.•Synoptic - Real WorldApplication - PhototherapyDeterminist/free will - PMS and SAD - Born et alrhythms can change through willpowerDisruption of Biorhythms• Shift Work and Shift Lag•Night workers experience ʻcircadian troughʼ (12-4am- between lowest cortisol and body temp level)-decreased alertness (Boivin et al 1996)•Sleep deprivation due to problems sleeping in theday - noise, family/social issues. 2 hours less sleepthan day workers•Effects on health - Knutsson et al 1986 - shiftworkers for 15 yrs+ 3 times more likely to to developheart disease. Martino (2008) - range of organdiseases including kidney - due to desynchronisationor sleep disruption.

Disruption of Biorhythms• Shift Work and Shift Lag•Commentary - Consequences may not just be due todisruption of biorhythms - social disruption (Solomon 1993 -divorce rates 60% higher in shift workers)•Gold et al 1992 - rotating shifts (shifts alternate every fewdays) are more disruptive than non-fluctuating shifts.•Bambra et al (2008) - Forward advancing shifts (phasedelay)easier to cope with and less harmful. Change shifts3-4 day intervals - better than 7 days for health and work/life balance•Artificial bright light can re-set rhythms (Gronfier 2007,Boivin 1996 )Disruption of Biorhythms• Jet Lag•Human biorhythms not equipped to cope with sudden and largechanges. Symptoms = loss of appetite, nausea, fatigue, disorientation,insomnia and mild depression.•Winter et al (2008) - takes one day to readjust to each hour oftime change• Phase Advance (get up earlier, go to bed earlier) and PhaseDelay (go to bed later and get up later - like a lie in)• Evidence - Recht et al (1995) - US baseball teams•Performance better when travelling East to West - Phase Delay(won 44% games), than travelling West to East (Phase Advance) 37%games won

Disruption of Biorhythms• Jet Lag• Commentary - Symptoms may be due to other factorsassociated with air travel e.g. noise, discomfort, low oxygen levels,drinking alcohol or coffee, anxiety, poor sleep before travelling, longjourney to airport, having to get up early to catch a flight e.t.c• Reducing harmful effects of Jet Lag -• Melatonin - ʻmiracle cureʼ - if taken just before bedtime it reducedjet lag symptoms (if taken at wrong time - delayed adaptation)Herxheimer and Petrie (2001)• Social Customs - sleep at same times as locals, stop eating,then eat on the new time schedule entrains rhythms, (Fuller et al2008) - possibly works because some body clocks are reset by foodintake.Disruption of Biorhythms• Synoptic Points.•Individual Differences - considerablevariation in circadian disruption betweenindividuals. ʻHappyʼ shift workers haverhythms that change less - Reinberg et al(1984)• Lab experiments were well controlled, butlacked ecological validity. Field experimentsbetter, but volunteer samples biased.

The Nature of Sleep -Ultradian Rhythms• Lasts for 90 minutes• Involves 2 types of sleep NREM and REM sleepwithin the 90 min cycle.• Repeats several times throughout sleepingperiod. Reliable, valid evidence from EEG, EOGand EMG +BRAC - BasicRest Activity Cycleensures biologicalprocesses workin unisonThanks to Eric H Chudler, University of Washington, Seattle USAThe Stages of Sleep1-4 =NREMStage 1 & 2 – relaxed state, easily woken, heartrate slows, temperature dropsStages 3 & 4 – Slow Wave Sleep (SWS),Metabolic rate slows, growth hormone releasedREM sleep – paradoxical sleep – brain and eyesactive, but body paralysed.

Nature of Sleep - Life Span Changes• Babies - sleep 16 hours, not continuously•Shorter sleep cycle (60 mins) - circadian rhythmestablished at 6 months•Active and quiet sleep rather than REM andNREM - half time in REM (more than adults)• Commentary - More Active Sleep/REM linkedto brain growth and development•Adaptive mechanism - gives parent chance toget on with chores - enhances survivalNature of Sleep - Life Span Changes• Children - Age 5 - sleep patterns like adults, butlonger period asleep•May experience parasomnias (e.g sleep walking,night terrors)• Adolescence - need for sleep increases (9-10hours)•Slight phase delay in circadian rhythms (stay up later andget up later)•Commentary - changes may be linked to hormonechanges (Crowley et al 2007). Implications for the schoolday (should start later!! - Wolfson and Carskadon - 2005))

Nature of Sleep - Life Span Changes• Adults and Old Age - Increase in sleepdisorders• Reduction of REM and SWS in old age•Older people experience phase advance (go tobed earlier, get up earlier)• Less night time sleep but more naps in the day•Commentary - Increased mortality rate with too muchsleep - Kripke et al 2007• Less sleep in old age may explain•impaired functioning in other areas.Nature of Sleep - Life Span Changes• Synoptic Points•Developmental Approach - focus on averagesignores individual differences•Sleep patterns may reflect culturaldifferences - East less than West•Tynjala et al 1993 - survey of 40,000 11-16 yearolds across Europe•Israeli children sleep least (8.5 hrs, Swiss 9.5hours)•Korea - 6.5 hrs (Shin et al 2003), Iran 7.7(Ghanizadeh et al 2008)

Restoration Theory of Sleep• The main predictions of Restoration Theory are:! Reduced functioning when sleep deprived! 'Rebound' effects following sleep deprivation! Increase in REM sleep during brain growth,reorganisation and repair! Increase in SWS during times of illness or injuryTheories of SleepOswald(1966)Restoration theories“Every stage ofsleep is essentialfor restoration!”“No! OnlySWS4 and REMare essential forrestoration!”Horne(1988)A. SWS1-4 are all needed:for repair/restoration ofthe bodyB. REM is essential: forrepair/restoration of thebrain1. ‘Core sleep’ = SWS4 + REM:essential for repair/restorationof the brain2. ‘Optional sleep’ = SWS1-3: notneeded at all for repair/restorationRestoration of the body happenswhen we are awake and relaxedhttp://www.psychology4a.com/biological_rhythms.htm

A02 - Evidence ForMany non-human animal studies have shown that sleep deprivation canlead to death - Rechtschaffen (1983), Jouvet (Cats) e.t.cLack of SWS leads to reduced immune functioning - Krueger et al 1985Van Cauter et al 2000 – decline of Growth hormone in old ageassociated with reduced SWS24 hour periodAgeREMNREM• Reduction in sleepover lifespan• Highest in infants;highest REM in earlyyears when braindeveloping• Some changes inadolescenceA02 - Evidence ForSleep deprivation studies - (1959 -Peter Tripp, 1965 Randy Gardner -evidence of reduced functioning and mild paranoia.REM Rebound - Dement (1960)PPs deprived of REM sleep seemed to have a need to catch up - REM reboundWhen allowed to sleep normally the participants spent much longer than normalin REM sleep, as did Randy Gardner.About 70% of lost SWS and about 50% of lost REM typically recoveredOnly some sleep is necessary‘Rebound’ suggests that sleep is a necessary functionMicrosleep - Williams et al 1959 - EEG recordings show periods ofmicrosleep after 72 hours sleep deprivation. Microsleep same as sleep.Total sleep time increases during illnessREM increases during recovery from brain injury, ECT & drug withdrawalREM sleep and memory - Crick and Mitchison 1983 - duringREM unwanted memories disposed of. Stickgold 2005 - REM consolidatesprocedural memory and SWS consolidates semantic and episodic memory

A02 -Evidence For• Generally the theory has HighFace Validity - it makes sense• It is easy to obtain quantitativedata on REM, amount oftransmitters e.t.c using bloodtests, EEG’s, fMRI’s and otherinstrumentationA02 - Evidence Against• Extrapolating from hamsters, cats and rats to humans isalways risky.• Some animals have no REM - so canʼt be for restoration• The research is not always RELIABLE and so wemight question its VALIDITY. ( Human sleep deprivationstudies and animal sleep deprivation studies – was itlack of sleep that killed the rats?)X Case Studies- 'Alien Among Us' criticismX - Humans donʼt die from lack of sleep!!Synoptic points -issues/ethics non-humananimals, methodology - casestudies - individual diffsRechtschaffen et al 1983 – rats died after being kept wakeon a moving disc for 33 days.Stress more likely the cause!

Ecological Theories of Sleep"Hibernation theory (Webb, 1974)" Evolutionary approach – sleep is assumed to give asurvival advantage" Sleep helps conserve energy by:" Reducing energy spent on behavioural activity" Drop in body temp & metabolic rate reduces energy lost as heatSize of animal - small will sleep longer than largeas need more energy to keep warmForaging Requirements - herbivores need to feedall day or night, carnivores need to eat less oftenPredator Avoidance - carnivores can sleep more,herbivores on look out for predatorsA02 Evidence For.." Comparative studies of different species generally supportevolutionary view" Smaller animals tend to sleep more than larger (e.g. giraffe 1hr vs.bat 20hrs)" Carnivores sleep more than herbivores (e.g. lion 16hrs vs. buffalo3hrs) - Alison and Cicchetti 1976" Animals generally sleep more when weather is cold and food isscarce (Berger & Phillips, 1995)"Circadian rhythms evolved to induce sleepat appropriate times of day – so they arelinked."NREM evolved first for energy conservationthen REM to to maintain brain activity -Capellini et al 2008

A02 - Evidence Against" Many evolutionary significant factors could affect sleeppatterns; theory doesn’t tell us which are important" Does a bat get so much sleep because it’s small or because it hasfew predators?" Some features of sleep cannot be explained easily by thehibernation theory:" Why is sleep universal when in some species (e.g. dolphins) itwould have been an advantage to get rid of it?" Why is sleep deprivation apparently fatal?" A criticism of all evolutionary explanations is thatarguments about adaptiveness and natural selection aremade post hoc (‘after the fact’ – after it happened)." We assume sleep is adaptive because they are still aroundtoday." But they may just be neutral and not selected out or linkedto another adaptive behaviour.Waste of Time Theory• Meddis 1975 - Sleep might simply be a way ofstaying still at time when an animal canʼt forageand would be subject to predation.•A Combined Approach - Horne 1988 proposeda theory that combines Restoration andEcological theories-• CORE Sleep - SWS needed for restoration•SynopticpointOptional Sleep - REM and NREM is foroccupying unproductive hours and conservingenergy

Sleep Disorders - Insomnia•Classification - Transient (short-term), Intermittent(occasional) or Chronic (constant and long term - morethan one month)• Causes•Secondary Insomnia - symptom of anunderlying disorder e.g depression, heart diseaseor due to shift work, caffeine or alcohol -Commentary - treat the disorder not the symptom - but Ohayon andRoth 2003 found that insomnia can precede mood disorders•Synoptic - Chronic Insomniahighly complex so can’t be explained by one factor and lotsof causes for insomnia so difficult to draw conclusionsfrom researchPrimary Insomnia - occurs on its own e.g.because of bad sleep habits (room too light,staying up late e.t.c)• Risk Factors -•••Sleep Disorders -InsomniaAge - older people more likely to sufferGender - women more likely to sufferSleep Apnoea and otherparasomnias (e.g bruxism, sleepwalking)- disrupt sleep and increaselikelihood of insomnia• Personality - linked to people with atendency to internalising problemsrather than act them out - anxiety andhigher levels of emotional arousal.Commentary -Watson et al 2006 - 50%risk of having insomniadue to genetics.Diathesis-stress model- environmentalstressors may trigger thedisorderPerpetuating factors -being tense before goingto bed because ofprevious sleep problems

Sleep Disorders - Narcolepsy• Definition - feeling sleepy all the time or episodes of cataplexy - loss ofmuscle control - triggered by emotional arousal e.g. anger, fear, amusement orstress. Usually starts in adolescence/early adulthood and persists through life.1/2000 are sufferers, but may be more prevalent.• Explanations -• REM - linked to a malfunction in the mechanism that regulates REM -explains cataplexy!! Vogel 1960 and Siegel 1999 - but support fromresearch not convincing•HLA - linked to mutation of the immune system - more of one type ofHLA found in narcoleptic patients. Not found in all narcoleptics and alsocommon in general population so canʼt be only explanation•Hypocretin - link between neurotransmitter hypocretin andnarcolepsy. Hypocretin helps maintain wakefulness. A promising lead asresearch in dogs and humans show lower hypocretin levels. Not thoughtto be inherited, more likely due to brain injury, infection, diet or stress orresult of an auto-immune attack (bodyʼs immune system turns on itself) MignotSleep Disorders - Sleep Walking•Definition - Most common in childhood, affecting 20% childrenand less than 3% adults. Only occurs during NREM/SWS and relatedto night terrors. Sleep walker not conscious and later has no memoryof events during sleep walking• Explanations -•Incomplete arousal - Person wakes during SWS but brainarousal incomplete. Likely that this is genetic. Diathesis - stress modelfits. 50% concordance in MZ twins, 10x more likely to SW if firstdegree relatives have disorder.•Sleep deprivation, alcohol, fever, stress and psychiatricconditions, hormonal changes during puberty and menstruation haveall been shown to increase likelihood of sleep walking - the stress partof the Diathesis-stress model•Synoptic - SW accepted asdefence in some crimesMore common in childhood possibly because they havemore SWS than adults. Oliviero (2008) suggests that the system thatinhibits motor activity in SWS is underdeveloped in some children andadults - evident in sleep walkers.