A rhythm that takes place around once every 24 hours, our EP is to keep our body synchronised with the earths rotation, as our cycle is naturally about 24.5 hours long whereas the earth rotates once every 24 hours. EZs resets our EP, the main EZ is light.
-Siffre- 205 days in the midnight cave, with no indication of time eg light, settled into 24.5 hour cycle, found more time had passed than he realised.
-Miles- 24.9 hour cycle of blind man, sedatives and stimulants
-Practical applications- can tell people when to take drugs to prevent death, eg strokes during night
-Biological evidence- EP is said to be in the supra chiasmatic nucleus in the brain, no longer vague
-Small samples- cannot generalise results
-Czeisler- artificial light such as in aschoff and wevers study could affect results, lack valdity
A cycle that happens less than once every day eg menstrual cycle. EP keeps our cycle regular for fertility. McClintock noticed womens cycles sync, she did a study in which she gathered samples of phremones of 9 women during their cycle by placing pads under their armpits. These sampples were wiped under the noses of 20 other women- 68% responded
-Russell- women that live together and take no oral contraceptives synch
-Russell- sweat samples, rubbed on upper lips of women, cycles synch with specific woman
-Empson- males have a 20 day cycle too, 21 patients 49-102 days, temp and mood
-Not sure why womens cycles synch
-Basketball team- no corresponding evidence
-Retrospective- women have to recall information about their mestrual cycle
A rhythm that occurs more than once every 24 hours, such as the sleep cycle, research tells us that our EP is very important becasue we are unconscious when we are sleeping, it's role is to make sure we have 5 cycles of the stages of sleep and then we wake up after the 5th, making sure we have enough REM two main EZ are intense exercise and daytime problems. A study by Dement and Kleitman found people woken during REM report dreams 80% of time, when woken in NREM only 7% reported dreams.
-All humans- biological evidence that it occurs in all humans
-Evidence- removal of the locus coeruleus resutls in no REM
-Inverted vision- wearing goggles that inverts the vision results in longer REM as the brain is presented with a problem, EZ can influence EP to give more time in REM
-Ecological validity- uncomfortable surroundings may affect validity
-Sleep changes as we get older and we have less REM and stage 4, we know little about this EP
-Recalling of dreams may not be a valid measure of whether the participants were dreaming or not
Disruption of Biological Rhythms
Usually all of our autonomic biological processes work together, peaking during the day and dipping at night, when we travel or do shift work we can desynchronise. Recht found when teams travelled from E-W thet won 46% of the time but when W-E only 37%
-Stokkan- fitting in with local times- practical applications
-Not well controlled- extraneous variables
-Sample- sample was only small
Czeisler did a study in a chemical plant about shift workers who were in short rotation, there was high incidence and health issues, he persuaded long rotations (21 days) and production increased.
-Changes may have been due to attitude due to having concern over workers health
-Small study- it may not be the same in bigger companies, can't generalise
-Little evidence- many people do shift work everyday, little disruption
The Nature of Sleep
Dement conducted lab experiments using EEGs, EMGs and EOGs to work out what happens during sleep. he found we have 4 stages and REM, 1 and 2 are light, 3 and 4 is deeper sleep. we descend and ascend, showing its not passive.
-Aserinsky and Kleitman- 8 year old son, brain activity, not passive
-Dement and Kleitman- people woken during REM , 80% dreams
-Found in all species of animals- much evidence
Research has shown we do most REM when we are younger about 60% and this decreases to 25% when we get to pre teen age. Van Cauter did a study on 149 male participants and took polygraphs. Stage 4 decreased from 20s to midlife, replaced with 1 and 2, old age- less sleep.
-Validty- measuring the sleep with electrodes
-Factors- older people more likely to take medication, which could influence sleep
-Borbely- older people take more frequent naps , could explain why they have less sleep
Meddis said the amount of sleep and animal has is linked to whether the animal is prey or not, prey animals sleep for long periods of time to burrow away, humans are naturally prey, babies have evolved to sleep for long periods of time to prevent exhaustion.
-Allison- 39 species of animals
-Non-falsifiable- which is unscientific
-Contradictory evidence- Zebras sleep lightly to remain alert.
-Different prey and predator species sleep for the same time eg foxes and rabbits 8.5 hrs
-Restoration theory would be more plausible
-Animals- can't generalise, we don't live in the natural world.
Oswald suggests that NREM serves to restore physiological processes and REM serves to restore psychological processes, different stages of sleep serve different functions, high brain activity during REM reflects brain recovery and the production of a growth hormone in stage 4 reflects body recovery.
-Babies- spend 50-60% of their sleep in REM, argued to be for the developing brain
-Drugs- those who survive drug overdoses increase the amount of time they spend in REM therefore it must serve a restorative function.
-Shapiro- ultra marathon man slept 11/2 longer the two nights after and spent 45% in stage 4
-Rosenzweig- intense exercise may cause individuals to fall asleep more rapidly
-Ryback and Lewis- healthy individuals spent six weeks resting in bed , sleep pattern had no change
-Lavie- a man who had been injured by shrapnel had experienced no REM sleep since, with no serious side effects
Primary- not attributable to medical, environmental or psychiatric cause. Secondary- caused by a psychiatric disorder. Genetics suggest it's an abonormality in the brain mechanisms controlling sleep wake in brains reticular activation system, solitary nuclei, raphe nuclei and medial forebrain, a neurochemical lesions exists. Personality - anxious.
-Morin- coping skills of stress of 38 women and 29 men, 40 had insomnia, relationship between day time stress and lack of sleep- lack of control
-Dauvilliers- 256 insomniacs, questionnaires and interviews, 72.7% reported familial link/24.1% NI
-Smith- study of neuroimaging of NREM sleep, evidence for abnormalities,eg decreased blood flow, compared to good sleepers in the frontal medial, occipital and parietal cortices.
-Soehner- measured sleep quality and duration(questionnaires) extraversion and neuroticism were also considered, no correlation found between personality factors
-Schramm- subjective to use lab recordings, test retest reliability
-Dement- can't generalise, too many types of insomina
Genetics- inherit faulty genes from parents, individuals are ten times more likely to sleepwalk if a first degree relative has a history of sleep walking and that it is more frequent in identical twins. Hublin found a strong genetic influence between twins.Sleep Dep- usually occurs during NREM deep sleep, more often during childhood- more deep sleep. Stress and alcohol influence it.
-Bassetti- 74 adult sleep walkers 16 went for genetic testing, 50% had a HLA gene only present in 24% of healthy people- so a higher incidence of the HLA gene
-Hublin- 11,000 participants higher concordance rates between MZ than DZ in adults 89% men 85% women showed a history of sleep walking during childhood.
-Dement- sleep walking tends to begin around 4 years, when daytime napping is given up, DEBT
-Zadra- 40 suspected sleep walkers sent to a clinic, found a clear link between sleep dep and sleepwalking, patients were monitored
-HLA- it remains unclear what the nature of the relationship is
-Small samples- can't generalise
Excessive daytime sleepiness, many also have cataplexy. Genetics- inherited, number of strains of dogs display narcolepsy when very excited, De Lecea found two peptides, hypocretins in the hypothalamus. people who have narcolepsy have lost 90% of their hypocretins. Neural- Von Economo said it is due to damage to the midbrain and hypothalamus. Scammell found a 23 yr old patient who had damage to is hypothalamus after a stroke- less hypocretins.
-Thannickal- dead brains of narcoleptics, 93% reduction in hypocretins
-John- injected hypocretins into narcoleptic dogs, it reduced their cataplexy
-Ohayon- study of 157 narcoleptics, 263 of their first degree relatives and a matched group without narcolepsy and found amongst the relatives 10% also had narcolepsy
-Picchioni- questionnaire to non/ narcoleptics, assess timing of stressors and infections, found a correlation between stress and development and certain infections
-Deterministic- it ignores environmental triggers and there must be one
-Animals- can't generalise the results found in the dogs to humans.