Discuss research on two biological rhythms - The infradian rhythms are rhythms that last longer than a day for example the human menstrual cycle, which occurs over a 28-day cycle.

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Discuss research on two biological rhythms:

The infradian rhythms are rhythms that last longer than a day for example the human menstrual cycle, which occurs over a 28-day cycle.

Research into infradian rhythms includes a study by Reinberg (1967); this study involved a woman spending 3 months in a cave with only the light of a miner’s lamp. As a result of this her days lengthened to 24.9 hours and her menstrual cycle shortened to 25.7 days. This study shows that the levels of light in the cave could have affected the woman’s menstrual cycle. After the study it took her body a year to readjust her menstrual cycle. This research shows how infradian biological rhythms can be influenced by external zeitgebers such as light. This research was also supported by findings that menarche’s is reached earlier in blind girls than sighted girls.

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There is also research to show that other factors than just light may affect the human menstrual cycle, these include pheromones released by other women. This was shown by a study of girls in a boarding school, these girls tended to have synchronised menstrual cycles. It has been suggested that the production of pheromones which synchronise menstruation may be evolutionary as it would have meant that women in the same groups had a greater chance of becoming pregnant at the same time this would have meant that if a mother had died another mother could breast feed her baby and ...

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