| What is the superachiasmatic nucleus (SCN)? | Main endogenous pacemakers and influential in maintining circaidan rhythms.
Lies above the optic chiasm and recieves information about light, continues with the eyes are close, allowing the biological clock to adjust to changing pattents of daylight when we are alseep |
| What was DeCoursey study? | Destroyed SCN connections int he brains of 30 chipmucks who were turened to thier natural habitat and observed for 80 days
Sleep/wake cycle disappeared and by the end a lot of them had been killed by pedators bc they were awake and vulnerable when they should have been alseep |
| Shiffre's study? | 61 days in cave supporting the presence of a endogenous pacemaker in the sleep/wake cycle as his cicadian rhythm maintained a regular rhythem without external cues |
| Aschoff and Wever study? | Found the free-running sleep/wake cycle is about 25 hours
-Light influences the circadian rhythm, the absense of light in the bunker means that the natural could be entrained with the ziethgebers.
Showed that eh endogenous pacemaker controlled by the sleep/wake cycle bc the ppts had a regualr and predictable rhythm |
| Stern and McClintock study? | -Mentrsual cylce, the role of zeitgebers hav ea role in ovulationa nd menstruation. Women can be seen to synchornise thier menstrual cycle with other women when exposed to a donor's pheromones in their cycle - influence of zeitgebers |
| What is entrainment? | When exogenous zeitgebers reset our biological clocks |
| What can light do to the SCN? | Can reset it and plays a role in the sleep/wake cycle as well sa has an indirect influence on hormoe secretion and blood circulation |
| What elese can entrain the sleep/wake cycle? | Social cues like mealtimes and bedtimes. Like in newborn babies, it takes them about 16 weeks to entrain their random sleep/wake cycle |
| Strength of endogenous pacemakers? | -Supporting research evidnece
-Menstrual cycle regulated by the hypothalamus, McClintock also shows the the role of zeigbers that can play a role in ovulation and menstruation. The idea of menstrual synchorny as women can snyc with others due to other women's peromones at different stages of the cycle
-However, significant eviednece to falsify the theory including a study conducted by Ziomkieicz foudn in 18 pairs and 21 triplits that menstrual synchony was not found. Social interactions was found to be unrelated to cause any differnece in mentstrual cycle onsets
-Supports the role of the endogenous pacemaker and casts doubt onto the influence of exogenous zeitgebers |
| A weakness of endogenous pacemakers? | -Can't be studied in isolated
-Total isolation studies, like Siffer's cave study are extreemly rare and even in this study Siffre made use of artifical light which could have reset his biological clock every time he turned his lamp on.
-In everyday life, endogenous pacemakers and exogenous zietbgebrs interact, and it may make little sense to separate the two for the purpose of research
-Suggests tha tmost reseachers attempt to isolate the influnece th internal pacemakers, the lower the validity of the research |
| A weakness of exogenous zeitgebers ? | -Doesn't have the same effect in all environment
-Expdrience of peopel who live in places where there is very little darkness in summer and very little light in the winter tell a different story to the usual narrative
-For instance, people who live in the artic cicle, ,like the Inuits of Greenland, have similar sleep patterns all year round, desptite spending around 6 months in almsot total darkness
-Suggests the sleep/wake cycle is primarily controlled by endogenous pacemakers that can override environmental changes in light |
| A weakness of exogenous zeitgebers? | -Evidence that challenges the role of exogenous zeitgbers
-Miles et al recount the study of a young man, blind from birth, who had abnromal cirrcadian rhythem for 24.9 hours.
-Despite exposure ot social cues, like reuglar mealtimes, his sleep/wake cycle could not be adjusted. Signifncant bc it suggests that social alone are not effective in resetting the biological rhythem
-However, findings of a case study can't be generalised to a wide population of peopel because it unrepresentative. |
