A03

• Point: A strength of menstrual synchrony research is that it could be explained using evolutionary psychology.

  Evidence: The adaptive value of synchronisation of menstrual cycles would mean our ancestors would menstruate together and likely become pregnant at the same time.

  Explain: This means that any babies that might lose their mother during or after childbirth still had access to breast milk from other mothers, which would improve their survival chances.

  Link: Therefore, synchronisation of cycles could potentially have evolved as an adaptive strategy.
• Point: However, a limitation of synchronisation studies is that there are methodological problems.

  Evidence: For example, these studies fail to control any other factors that may act as confounding variables. 

  Explain: This means variables such as stress, diet changes, exercise all would have to be controlled as they all impact menstrual cycles or otherwise no causal conclusion can be drawn.

  Link: Therefore, this suggests that such research is flawed and also why other studies have failed to replicate the findings.
• Point: A strength of research into ultradian rhythms is that it has developed our understanding of age-related changes in sleep.

  Evidence:  For example, Eve and Cauter (2000) has shown that slow wave sleep (SWS) reduces with age and that growth hormone is mostly produced during this stage.

  Explain: This means that the sleep deficit in old age can explain issues like reduced alertness, which can be counteracted by relaxation and meditation to increase SWS again.

  Link: Therefore, this shows the practical value of such research as it can be used to help old people.
• Point: A limitation of sleep studies is that it may lack external validity.

  Evidence: For example, many sleep studies are conducted in lab settings which allow the researchers to control any extraneous variables that might affect sleep, like noise and temperature.

  Explain: These artificial settings combined with participants being attached to complicated machinery might lead them to sleep in a way that does not represent their normal sleeping patterns.

  Link: Therefore, it is hard to generalise data obtained from controlled sleep studies in lab settings to sleep in an everyday context.