Key studies for Unit 3 Biological Rhythms and Sleep

All the studies needed for Unit 3 Biological Rhythms and Sleep.

Did it for my own revision, so sorry if it doesn't make complete sense, it is in brief note form!

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  • Created by: Gabi H
  • Created on: 05-06-12 12:36
Preview of Key studies for Unit 3 Biological Rhythms and Sleep

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Morgan Removed SCN from hamsters ­ circadian rhythms disappeared. Given
SCN cells from foetal hamsters, rhythms re-established. Transplanted
SCN cells from mutant hamsters (circadian rhythms 20 hours) ­ recipient
hamsters took on mutant rhythms
Zucket Similar effects of SCN destruction in ground squirrels
Campbell Participants ­ regular light exposure on back of knees ­ changes in
circadian rhythms
Wight and Czeisler Failed to replicate findings
Luce and Segal People living near Arctic circle ­ sun throughout summer months ­ 7
hours sleep a day. External cues take over.
Siffre 205 days ­ Cave ­ Texas ­ ate and slept at will. When awake ­ lights on,
when asleep ­ lights off. Initially, sleep/wake cycle variable, settled
down 25-27 hours
Wever Participants - weeks/months bunker ­ consistent cycle 25 hours.
Folkard Participants 3 weeks ­ cave ­ quickened clock 24 hours when only 22
hours ­ only one able to adapt
The role of endogenous pacemakers and exogenous zeitgebers
The disruption of biological rhythms
Recht Baseball results ­ 3 year period ­ USA. Playing games within time zone
won 46% games, almost as well when travelling west. Travelling west to
east ­ won 37% games
Tilley and Wilkinson Shift workers sleep 1-2 hours less during day than they would at night,
REM particularly affected
Knutsson Shift workers for 15 years ­ 3x more likely ­ heart disease. Sleep
deprivation linked with type II diabetes, hypertension, gastro-intestinal
Schernammer 10 year study 78000 US nurses - risk of breast cancer increased
significantly ­ number of years working rotating night shifts
Czeisler Chemical plant ­ Utah ­ recommending optimal shift pattern ­ changing
shifts, every 21 days, in a forwards rotation (phase delay).
9 months later ­ increased job satisfaction/productivity ­ decreased
health problems/accident rate
Czeisler Strong artificial light can reset body temp and cortisol production within 3
days ­ quicker than normal
Gordon Philadelphia police officers ­ forwards rotation ­ 30% reduction sleeping
on job ­ 40% reduction accidents
Takahashi Melatonin speeded up resynchronisation of biological rhythms, reduced
symptoms jet lag
Sharkey Melatonin could speed up biological adjustment to shift patterns,
increased sleep time

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Research into the nature of sleep, stages of sleep, lifespan changes in sleep
Dement and Kleitman Woke participants during different stages sleep ­ monitoring EEG
record. Awakened during REM ­ dreams 80-90%. NREM sleep ­ dreams
7% time
Ohayon Meta-analysis ­ 2400 healthy adults 5-102 years ­ age-related changes
in sleep ­ decrease in total sleep time, changes in structure of sleep,
shifts in NREM and REM sleep.…read more

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Horne Restoration explanation 2 ­ restorative processes of body take place
during periods of relaxed wakefulness
Shapiro Runners ­ 57 mile race ­ slept an average of 90 mins longer on the 2
nights following race ­ increased levels SWS. Not a huge increase.
Increased SWS could be consequence of increased body temp produced
by exercise.…read more

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Adult sleepwalking could be
result of GABA mechanism remaining underdeveloped
Bassetti Nature of genes underlying sleepwalking may be related to same HLA
gene abnormality associated with narcolepsy
Broughton Incidence of sleep walking in first-degree relatives of someone with the
disorder = 10x greater than in general population
Lecendreus 50$ concordance rate MZ twins compared to 10-15% DZ twins
Bassetti 74 adult sleepwalkers ­ of the 16 patients underwent genetic testing
50$ had a version of HLA gene found in only 24% non-sleep walkers.…read more


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