Biological Rhythms & Sleep
- Created by: Jack Takeda
- Created on: 28-04-16 15:12
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- Siffre (1972)
- Stayed in a cave for 6 months - separated from light/dark cycles. His sleep-wake cycle extended to between 25-32 hrs (days became longer). His body also maintained a circadian rhythm - eventually his body temp & sleep-wake cycle decoupled (internal desynchronisation)
- Innate mechanism for circadian rhythms that will function without external cues.
- Stayed in a cave for 6 months - separated from light/dark cycles. His sleep-wake cycle extended to between 25-32 hrs (days became longer). His body also maintained a circadian rhythm - eventually his body temp & sleep-wake cycle decoupled (internal desynchronisation)
- SCN [Suprachiasmatic nucleus] - a tiny cluster of cells in HYPOTHALAMUS could be site for at least 1 EP.
- [A01] Stehan & Zucker (1972) - compared rats with damage to the SCN & normal rats. Found that those with damaged SCN eliminated the normal circadian patterns of drinking & activity.
- Suggets SCN is a key EP in controlling circadian rhythms
- [A02] Morgan (1995) found that if a damaged SCN is transplanted into a normal hamster they now showed distorted circadian rhythms
- BIOLOGICALLY REDUCTIONIST - this may be relevant for understanding animal behaviours it is likely that other external factors eg. social cues play a role in shaping human circadian rhythms eg. sleep/wake cycle.
- ETHICAL ISSUES - Stephan & Zucker study, out of 25 hamsters only 11 survived. Although can be argued that the costs of animal suffering is justified by the potential benefits for understanding sleep/wake disorders.
- EVOLUTION - Biological clock may be adjusted by EP's. Therefore not constrained to rigid, innate schedule. Could have an advantage in having EP's reset by EZ's - keeping in tune with seasonal changes: to rely solely on EZ's could threaten survival, internal cues are important too
- ETHICAL ISSUES - Stephan & Zucker study, out of 25 hamsters only 11 survived. Although can be argued that the costs of animal suffering is justified by the potential benefits for understanding sleep/wake disorders.
- BIOLOGICALLY REDUCTIONIST - this may be relevant for understanding animal behaviours it is likely that other external factors eg. social cues play a role in shaping human circadian rhythms eg. sleep/wake cycle.
- [A02] Morgan (1995) found that if a damaged SCN is transplanted into a normal hamster they now showed distorted circadian rhythms
- Suggets SCN is a key EP in controlling circadian rhythms
- [A01] Stehan & Zucker (1972) - compared rats with damage to the SCN & normal rats. Found that those with damaged SCN eliminated the normal circadian patterns of drinking & activity.
- Stage 1: Light Sleep (Ocassional muscle activity 4-5%). Stage 2: Heart rate slows (45-55%) Stage 3: Deep Sleep [SLOW Delta waves produced] (4-6%). Stage 4: Very Deep Sleep [Delta waves produced] (12-15%). REM: Dreams [High activtity, muscle paralysis] (20-25%)
- Stages of Sleep
- Dement & Kleitman (1957) - Observed if pps awakened in periods of REM/NREM. REM sleepers able to recall dream easier. All pps showed periods of REM during sleep. REM never occurred at the beginning of sleep.
- Objective Evidence - EEG, EOG, EMG provide objective measures of sleep (less bias)
- Lacks mundane realism - too artificial findings lack generalisability & ecological validity
- Sleep varies from individual - not everyone will have the same sleep pattern
- Lacks mundane realism - too artificial findings lack generalisability & ecological validity
- Objective Evidence - EEG, EOG, EMG provide objective measures of sleep (less bias)
- Dement & Kleitman (1957) - Observed if pps awakened in periods of REM/NREM. REM sleepers able to recall dream easier. All pps showed periods of REM during sleep. REM never occurred at the beginning of sleep.
- Dement & Kleitman (1957) - Observed if pps awakened in periods of REM/NREM. REM sleepers able to recall dream easier. All pps showed periods of REM during sleep. REM never occurred at the beginning of sleep.
- Objective Evidence - EEG, EOG, EMG provide objective measures of sleep (less bias)
- Lacks mundane realism - too artificial findings lack generalisability & ecological validity
- Sleep varies from individual - not everyone will have the same sleep pattern
- Lacks mundane realism - too artificial findings lack generalisability & ecological validity
- Objective Evidence - EEG, EOG, EMG provide objective measures of sleep (less bias)
- Stages of Sleep
- Predatory Theory (Meddis,1975) Sleep is adaptive because the immobility of sleep keeps animals safe from predators at most vulnerable. It is also a time when normal activities are impossible. Also it is during a time when normal activities are impossible.
- Evolutionary
- [A02] Sleep leaves animals more vulnerable as they are in a state of unconsciousness & paralysis. Thus protection is unlikely the main function.
- Evolutionary
- Only NREM has evolved for energy conservation. Alison (1976) larger animals had less NREM but not less REM.
- NREM evolued first for energy conservation, REM evolved later to maintain brain activity. Supported by the need for REM in infants whose brains are developing.
- To repair & recharge the brain & body through restoring energy resources.
- Restoration Theory
- Sleep Deprivation
- Peter Tripp - Radio DJ stayed awake for 8 days. He experiences delusions and hallucinations. No effect on physicality
- Rechtschafffen (1983) - Placed 2 rats on a disc above water. One was able to sleep the other was not. All of the sleep deprived rats died by 33 days: The rats that were not sleep deprived appeared to suffer no ill effects as the study (died due to inability to regulate body temp)
- Lab setting - increases internal validity but may have affected the sleep pattern not in their natural setting.
- Functions of Sleep
- Evolutionary
- [A02] Sleep leaves animals more vulnerable as they are in a state of unconsciousness & paralysis. Thus protection is unlikely the main function.
- Evolutionary
- Sleep Deprivation
- Many restorative processes - digestion & protein synthesis occur in sleep.
- REM is far higher in babies than adults and even higher in premature babies. With the development of synaptic connections & neurotransmitters.
- [AO2] Krueger 1985 - Lack of SWS associated with reduced functioning of the immune system. Immune system is 'regenerated' during cell growth & protein synthesis in SWS
- [A02] Ryback & Lewis (1971) - Found healthy pps who speant 6 weeks resting in a sleep lab showed no changes in their sleep patterns
- [AO2] Krueger 1985 - Lack of SWS associated with reduced functioning of the immune system. Immune system is 'regenerated' during cell growth & protein synthesis in SWS
- REM is far higher in babies than adults and even higher in premature babies. With the development of synaptic connections & neurotransmitters.
- Restoration Theory
- Lifespan changes of Sleep
- Ohayon (2004) Sleep tends to become lighter with age. Stage 2 used to be 42& of sleeptime by 70 takes up 55%.
- Suggests sleep has different functions @ different ages. eg. - babies = more REM for development.
- Restorative/ Adaptive Function - Long unresponsive REM sleep in infants may have allowed parents to rest .
- Sentinel theory - that REM in adults evolved to allow checking for signs of danger in the short periods of wakefulness that occurs @ end of each episode of REM sleep.
- Functions of Sleep
- Ohayon (2004) Sleep tends to become lighter with age. Stage 2 used to be 42& of sleeptime by 70 takes up 55%.
- Insomnia
- Primary = Not attributed to medical, psychiatric or environmental cause.
- Secondary = caused by psychiatric disorder or medical disorder
- Spielman's Cumulative Model (1987) Predisposing Fctors - perfectionism, sensitive types etc. precipitating factors (environmental factors) can trigger disorder. Perpetuating factors may maintain the disorder even when stressors have gone (bad thoughts/habits)
- [A03] - Allows for an eclectic approach to understanding & treatment. It is flexible as each persons factors may vary and this avoids a simplistic explanation
- Psychophysiological Insomnia - learn to associate sleep with anxiety (classical conditioning)
- Dauvillers (2005) - Primary insomniacs completed clinical interview, questionnaire on family history and polysomnography . 72% reported familial insomnia compared with 24% in control. Sugegst familial link to primary insomnia
- FOR A02+A03 CHECK PAST HW
- Gregory (2006) - Family conflict & Insomnia. Family conflict at 5-15 resulted in insomnia at age 18.
- Correlational so may be other variables at play like individual personalities.
- Secondary = caused by psychiatric disorder or medical disorder
- Psychophysiological Insomnia - learn to associate sleep with anxiety (classical conditioning)
- Dauvillers (2005) - Primary insomniacs completed clinical interview, questionnaire on family history and polysomnography . 72% reported familial insomnia compared with 24% in control. Sugegst familial link to primary insomnia
- Inherit a genetic variation that increases the risk of SW. 10 x more likely if a 1st degree relative has a history of SW.
- Bassati (2002) - found that 50% of 74 SW studied had a specific HLA gene that was only seen in 24% of the non-SW (HLA helps pregulate immune system & implicated in other sleep disorders.
- Suggests a genetic link to SW
- Bassati (2002) - found that 50% of 74 SW studied had a specific HLA gene that was only seen in 24% of the non-SW (HLA helps pregulate immune system & implicated in other sleep disorders.
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