test 2 Flashcards
careful study of circadian rhythms in people requires…
isolate from zeitgebers
constant environments for studying sleeo?
deep underground caves
laboratories
- constant temps and total darkness
who spent time in kentuckys mammoth cave and for how long
nathaniel kleitman and bruce richardson, 32 days
who spent a lot of time in underground caves
michel siffre spent time in caves and underground glaciers in multiple experiments — he was alone in the original studies and calling up to a research team to report
who used a WWII bunker
aschoff and Wever used an underground bunker from WWII modified into a well-equipped and isolated lab for studying individuals living in time-free environments
did lots of people ask to end time in the sleep cave early?
ery few participants found the isolation to be disturbing or asked to be released early
what did aschoff and wever find - interesting finding
Aschoff and Wever reported that some participants developed a strong interest in guessing the time in the external world
- Guessing research assistant’s schedules relative to external time (day crew or night crew)
- Studies in hospitals or universities, participants could feel vibrations from elevator shafts, thus able to guess when the workday started and ended
- Experiments had to work on irregularly staggering schedules to conceal information about the time of day
Without cues, meal patterns, body temperature, and sleep-wake cycles free-run with periods…
different than 24 hours
Spontaneous desynchronization?
different rhythms with different periods
Spontaneous desynchronization examples
Eg. Some participants showed sleep-wake cycles much shorter or longer than 24 hours, while body temperature rhythms free-ran with periods close to 24 hours
spontaneous desynch example siffre
Michel Siffre reported sleep-wake cycle of 50 hours in some cases, but body temperature stayed in circadian range
- This is a bit extreme, his probably ran a little long naturally
- Did cognitive testing: took him a long time to count to three for example, his personal perception of time was longer
those with very long sleep wake cycles
- Average hourly activity levels were lower
- Ate meals at longer intervals
- Estimated an hour as being longer
- Had lower average body temperature
those with very short sleep-wake cycles
- Average hourly activity levels were higher
- Ate meals at shorter intervals
- Estimated an hour as being shorter
- Had higher average body temperature
people with very long and short sleep wake cycles found to…
be active for the same total time at the end
in controlled environments with no external time cues what can still be an issue?
some variables can still affect measurement of rhythms
the circadian rhythm of body temperature responds to a number of masking effects
Large meals increase sleepiness
Exercise increases body temperature
Body temperature decreases during sleep
Even if researchers attempt to limit external variables (eg. Alarm clock), there are still…
many effects that can occur even through participants self-selected patterns
what things can researchers not control in measuring sleep
Body temperature, some hormones, change depending on whether a person is laying down, standing or sitting
Campbell and Broughton study
Purpose:
clarify the temporal relationship between the nightly decline in body temperature and the timing of the onset of nocturnal sleep
Campbell and Broughton whole study
???
Campbell and Broughton correlation
Significant positive correlation between the amount of wakefulness within the first hour after initial sleep onset and MROD relative to both bedtime and sleep onset
- That is, the closer MROD occurred to either bedtime or sleep onset, the less wakefulness there was within the first hour after sleep onset
Campbell and Broughton findings
- Findings indicate that the process of sleep initiation is most likely to occur when the body temperature is declining at its maximum rate and is most successfully accomplished at this phase of the temperature cycle
- If you were too warm when trying to go to bed (artificially raising body temp), it can be hard to fall asleep
- Feet should be warm
internal masking
changes in the value of a target measure (Eg. Body temperature) that result from the participant’s own behaviour rather than from either an external disturbance or the dictates of the circadian clock
internal masking examples
Doing exercise, eating a big meal, etc. could change one of their cycles