Biological Rhythms

Circadian Rhythm - 24hrs e.g. SLEEP-WAKE CYCLE

Endogenous pacemaker - internal biological clocks

exogenous zeitgebers - external cues (e.g light, noise, food)

SLEEP WAKE CYCLE

• michael siffre ( in cave) - cycle settled to just over 24hr. case study.
  
• Folkard - speeding of clock - cycle remained at 24hrs, not 22hrs
• use of lighting? dim light's??
• individual differences - cycles of 13 - 65hrs
• morning / night people ( larks and owls)
  
• chronotheraputics - timing of medication
  

CORE BODY TEMP

• lowest at 4.30am, highest at 6.00pm. dip/trough at 1.00pm (bi-daily rhythm)
• cognative abilities - Folkard (story recall) , Gupta (IQ)
• suggestion- ^ temp = ^ arousal = ^ cognative ability
• school starting time dispute

HORMONES

• Cortisol levels peak at 6.00am - alertness
• melatonin levels peak at 12.00 am - sleepiness

BIOLOGICAL APPROACH

• Determinism
• can overide to a point, but not completely
• blind boy - internal clock ahead - use of stimulants and sedatives

Ultradian rhythm - less than a day (sleep cycle)

SLEEP CYCLE

• SWS - stages 1&2 (light sleep) Stages 3&4 ( deep sleep, production of GH)
• cycle lasts 90 minutes
• REM - dreaming - dement & kleitman. waking during REM, most dreaming

BRAIN REST-ACTIVITY CYCLE

• 90 minute cycle inside sleep-wake cycle
• Freidman and Fisher - eating/drinking. psych patients > ethical issues
• forms timing for biological processes to work in unison

infradian - more than a day, less than a year (menstrual cycle)

MONTHLY CYCLES

• menstural cycle - Russel et al - syncronisation (sweat on lip) phenomones
• PSM - Symptoms may lad to crimes. Ms English - murder of husband
• temperature cycle in men is apparent (22 days)

Seasonal affective disorder (SAD)

• depression in winter
• darkness - increased levels of melatonin and seratonin
• phototherapy (light box) - very effective, more than placebo light box

Endogenous pacemakers - internal rhythms

THE SCN

• obtains light information from the optic nerve
• ventral SCN - quickly reset by external cues
• dorsal SCN - less effected by external cues 
• mutant SCN transplanted into hamster - mutation of internal rhythm
• chipmunk - removal of SCN - killed by predators (awake when awake)
• desynchronisation - symptoms as of jet lag

THE PINEAL GLAND AND MELATONIN

• SCN > signals to pineal gland > ^ production of melatonin at night
• regulated by light - production inhibited in light

Exogenous zeitgebers - external cues

LIGHT

• can reset SCN and protein clock (light sensative)
• cambell & murphy - light on knees - protein clock
• industrial societies/ well lit -  ^ breast cancer - disruption of circadian rhythms
• early circadian testing - use of dim light??
• recent research - dim light still effects circadian rhythm

SOCIAL CUES

• meal times, bed times, wake times

TEMP

• dominant in the absence of light
• hibernation

 shift work = disruption of circadian rhythms

• decreased alertness at night - production of melatonin
• sleep deprivation - daytime distuptions. decreased REM of 2hrs
• increased risk of heart disease - Knutson
• social disruptions - increased divorce rates
• rotating shifts / forward rotation is good
• use of artificial lights and melatonin 
• individual differences - some people unaffected
• lab experiments - v extraneous variables, also v generalisability

Jet lag = disruption of circadian rhythms

• east to west is best (easier to sleep later than wake earlier)
• biological rhythms are not equipt to deal with big sudden changes
• winter et al - recovery - 1 day per hour time difference
• decreased performance (baseball wins - 44% home, 37% away)
• effected by other factors (e.g. caffine and alcohol)
• Melatonin use - Jet lag miracle cure
• social customs - flight starvation - reset biological clocks

INFANCY

• sleep 16hrs per day. v sleep cycle time. ^ REM
• at one year old infants sleep mainly at night
• adaptive sleep patterns - ^ survival
• ^ REM - production of neurotransmitter and consolidation of memory

CHILDHOOD

• EEG paterns like that of an adult
• 12hrs sleep, 30% REM
• parasomnias may occur

Adolescence

• circadian rhythms change - awake later at night (sleep-phase syndrome)
• hormonal changes
• males may organsm and ejaculate in sleep

ADULTHOOD

• parasomnias decrease
• disorders such as sleep apnoea and insomnia
• too much sleep = ^ risk of mortality ( 30% ^ at 10hrs sleep a night). Underlying factors? illness may ^ sleep, and also result in mortality)

OLD AGE

• wake up more in the night
• day time naps to compensate waking
• REM decreases to 20%
• phase advance syndrome (get up earlier, go to bed earlier)
• decresed SWS, decreased GH production (symptoms of old age)

OSWALD PROPOSED THAT SWS ENABLES BODY REPAIR, REM ENABLES BRAIN RECOVERY

SWS

• growth hormone secreted (protien synthesis)
• Sassin et al - SWS reversed -> GH production also reverses
• suggests GH is controlled by same mechanisms as SWS
• decresed SWS = decresed immune system (due to decreased protien synth)

REM

• brain growth - evidence from babies (lots of REM) brain immature at birth
• REM = break in neurotransmitters = neurones regain sensitivity
• support from MAIO's - side affect, no REM, as monoamine receptors dont need to be replemished
• REM IS IMPORTANT FOR CONCOLEDATION OF PROCEDURAL MEMORY
• during REM, unwanted memories are discarded, making more important memories accessible.

EFFECTS OF TOTAL SLEEP DEPRIVATION

• PETER TRIPP. case study.
• microsleep (after 72hrs) non-sleeper gets benefit of sleep
• studies on rats, fatal consequences, all diead after 33 days. stress may be cause.
• rattenburg - pigeons had no ill effects

EFFECTS OF PARTIAL DEPRIVATION

• REM rebound, increased REM the next night
• Empson - depriving pps of REM, instantly went back to REM after waking
• recovery nights - 50% more REM

EXERCISE AND NEED FOR SLEEP

• horne & minard - pp's fell asleep quicker, not for longer
• marathon runners - 2 hours more sleep after a race

EVOLUTIONARY EXPLAINATION

• energy conservation- period of reinforced inactivity
• foraging- herbivores sleep longer than carnivores
• predetor avoidance - sleep when predetors are awake, increases survival
• waste of time (Meddis) - stay out of way when most vulnerable (hidden)
• siegel agrees - being awake is more risky, noise attracts predetors
• smaller animals - ^ metabolic rate = ^ sleep needs, Zeplin. (exceptions, sloth)
• Energy conservationin NREM only - primative reptiles have NREM only
• REM evolved later to maintain brain activity 
• Horne suggests Core sleep and Optional sleep
• Core: requires for essential processes (SWS)
• optional : dispensable, occupying unproductive hours (REM)
• Unilateral sleep, evoluationary adaptation. Dolphins, Ducks, etc.
• evolutionary approach fails to address some key aspects
• combined approach (evolutionary and restoration) explain all aspects

primary- occured on its own secondary - as a result of underlying condition

Risk factors

• age - older people - physical problems
• gender - women - hormonal changes (menopause)
• personality- internalising distress
• genetic predisposition - 50% concordance (identical twins)
• diathesis stress model - vulnerability + stress = insomnia
• perpetuating factors - e.g. being tense at bed times
• roberts et al - teen insomnia, 25% had symptoms, of that 41% 1 year later

Treatment of insomnia

• attribution theory - "stimulant" pill - sleep easier due to attribution of wakefullness blamed on pill, and therefore relaxation occured
• increasing sleep hygine (healthiness of habits, eg not drink alchohol)
• use of melatonin
• sleep restriction - no sleeping outside designated hours

NARCOLEPSY

• symptoms - sleepiness all the time, and cataplexy
• malfunction in mechanism that controls REM sleep (explains cataplexy)
• REM hypothesis- vogel. cataplexy is linked to the activation of cells only active in normal animals during REM. But research has not been convincing
• mutation of HLA (immune system), one variant found in many narcoleptic patients, hovwever, not in all, and is common in general population
• link between hypocretin and narcolepsy, distuption of hypocretin found in narcoleptic dogs.
• Nisho, narcoleptics had less hypocretin
• not likely to be linked genetically , may be due to brain injust, stress, diet or auto-immue attack (this would explain HLA link)

SLEEP WALKING

• affects about 20% of children
• occus only in SWS, and is linked to night terrors
• disorder of arousal - incomplete arousal - abnormal arousal is genetic
• may be due to stress, fever, or psychiatric conditions
• oliviero- suggests that SW occurs due to underdevelopment of motor activity that usually inhibits SWS
• fits in the diathesis stress model
• 50% concordance in identic twins (diathesis)
• lack of maturity in neural sleep circuits (stress) 
• used as a criminal defence - Joules Lowe, killed his father, not guilty due to previous violent SWing and further testing in a sleep lab, condemmed to a psychiatric hospital
• difficult to diagnose