Sleep Flashcards
Ralph
Circadian rhythms
Endogenous pacemakers
Took SCN from mutant breed of golden hamster with a circadian rhythm of just 20 hours and transplanted it into a hamster with a 24 hour rhythm, the normal hamster then started to show a shorter rhythm
Siffre
Circadian rhythm
Exogenous zeitgebers
Lived in a cave for 6 months away from natural light and other EZs, be asked for light on when he was awake and light off when he was going to sleep allowing his biological clock to be free running, he settled into a 25 hour cycle, so he therefore felt like fewer days had passed, and his cycle was slightly longer
Suggests that EZs are important in the fine tuning of circadian rhythms
Russel et al
Infradian rhythm
Menstruation
EZ
Collected swear from one woman each day and rubbed it under the noses of another woman each day. Found that the second woman’s menstrual cycle started to become synchronised with that of the first woman
Suggests that EZ are an influence on natural rhythms
Recht et al
Disrupting rhythms
Jet lag
19 baseball teams over 3 years
Teams performed significantly better travelling East to West
E-W: won 44% of games
W-E: won 37% of games
Schernhammer
Disrupting rhythms
Shift work
Used data on the health of 78,000 US nurses. There was a significant correlation between number of years working shifts and risk of breast cancer, even when other risk factors were controlled for
Dement and Kleitmen
Nature of sleep
Ultradian rhythm
Studied 9 people for up to 61 nights in a sleep lab to monitor their sleep stages using an EEG. They were the first to describe the different patterns of nREM and REM sleep, which is an ultradian rhythm
Czeisler
Disrupting Rhythms
Solutions
Study of Utah Chemical Plant which operated backward rotating shifts, changing every 7 days, which caused sleep problems, and high stress levels. Changed to forward rotation, changing shift every 21 days.
After 9 months the workforce was reassessed. Sleep problems had reduced, stress decreased and productivity improved
Zepelin and Rechtshaffen
Function of sleep
Energy conservation Theory Support
Found a negative correlation between the animal’s body size and amount of sleep required across 53 species of animals
Mice slept around 20 hours, while elephants only slept around 4 hours
Allison and Cicchetti
Function of Sleep
Predator avoidance
Correlational analysis of the sleep patterns of 39 species and their risk of predation. There was a negative correlation - those who were most at risk slept the least
Rechtschaffen
Function of sleep
Restoration
Put rats above cold water, whenever they started to go to sleep the disc was rotated until they woke up, if they didn’t wake up they were pushed into the water.
They lost weight despite the eating and showed a breakdown in temperature control.
All died between 13 and 21 days
Ohayon et al
Nature of sleep
Life span changes in sleep
Meta-review of 65 studies of sleeping patterns from 5 - 102 yo. Total sleep time decreases from 17 hours in newborns to 6 hours at 70 yo
REM decreased from 25% @ 5 yo to 19% @ 70 yo and the % of deep SWS stage 4 sleep is larger in children than adults
Nofzinger
Disorders
Primary Insomnia
Hyperarousal
PET scans whilst insomniacs feel asleep
Normally: sleep indicated by a decrease in activity in key brain areas
Primary insomniacs: decrease in brain activity was not as great
Watson
Disorders
Genes and Primary Insomnia
1000 MZ and 800 DZ where one twin had insomnia
Concluded that up to 50% of the variance in insomnia may be genetic
Katz
Disorders
Secondary Insomnia
Survey of 3,500 people with chronic medical conditions, and over half reported symptoms of insomnia
Bassett
Sleep Walking
SWS sleep patterns
Brain scans showed increased activity in areas of the brain that regulate emotion and decreased flow in the areas that monitor behaviour
