Infradian Rhythms

Summary

This lesson delves into infradian rhythms, specifically focusing on the menstrual cycle and Seasonal Affective Disorder (SAD). It explains how internal factors like hormones and external influences such as pheromones and light affect these cycles. The role of synchronization in the menstrual cycle is discussed, along with the evolutionary benefits and potential confounding factors. SAD is linked to melatonin overproduction and light exposure, with phototherapy suggested as a treatment. The lesson highlights the complexity of biological rhythms and their interaction with both internal and external factors.

Takeaways

• 📚 The lesson focuses on infradian rhythms, which are biological rhythms longer than a day, including the menstrual cycle and Seasonal Affective Disorder (SAD).
• 🌊 Infradain rhythms are distinguished from circadian and ultradian rhythms by their less frequent periodic cycles.
• 🔬 The menstrual cycle is controlled by hormones like estrogen and progesterone, which are internal factors, and can be influenced by external factors such as synchronization with other women's cycles.
• 🌡️ Synchronization of the menstrual cycle can be influenced by pheromones, chemical signals released into the environment that can affect others' internal mechanisms.
• 🧬 Martha McClintock's study showed a correlation between close living conditions and menstrual cycle synchronization among women in an all-female dormitory.
• 🤔 The role of pheromones as internal or external factors in biological rhythms is a point of analysis, given their release into the environment but biological origin.
• 🕰️ A study involving a woman in a cave without natural light showed that the absence of light can affect the menstrual cycle, indicating light as an exogenous factor.
• 🌞 The evolutionary value of menstrual cycle synchronization may include shared childcare and fair competition for mates, though this idea is debated.
• 🌨️ Seasonal Affective Disorder is a type of depression with symptoms like low energy and social withdrawal, linked to reduced daylight during winter.
• 🌞 Endogenous factors in SAD include overproduction of melatonin and underproduction of serotonin, while exogenous factors are the absence of light.
• ✨ Phototherapy, or light exposure, has been effective in treating SAD, suggesting a strong link between light and the disorder's symptoms.

Q & A

What are infradian rhythms in the context of biopsychology?

Infradian rhythms are biological rhythms that occur over a period longer than a day, as opposed to circadian and ultradian rhythms which have more frequent cycles.

What is an example of an infradian rhythm mentioned in the script?

The menstrual cycle is given as an example of an infradian rhythm in the script.

What is Seasonal Affective Disorder (SAD)?

Seasonal Affective Disorder is a type of depression that occurs during the winter months, characterized by symptoms such as low energy, hypersomnia, weight gain, and social withdrawal.

How do infradian rhythms differ from circadian and ultradian rhythms?

Infradian rhythms have a less frequent regularity compared to circadian rhythms, which include the sleep-wake cycle and hormonal fluctuations, and ultradian rhythms, which include stages of sleep like REM and non-REM sleep.

What role do estrogen and progesterone play in the menstrual cycle?

Estrogen causes the ovary to develop an egg which is released during ovulation, while progesterone helps the womb lining to thicken in preparation for pregnancy. If the egg isn't fertilized, the lining is disposed of, resulting in the menstrual cycle.

What is synchronization in the context of the menstrual cycle?

Synchronization refers to the phenomenon where being around other people on their menstrual cycle can influence one's own menstrual cycle, possibly due to the influence of pheromones.

What is the evolutionary value of menstrual cycle synchronization according to the script?

The evolutionary value of synchronization could be that if women menstruate and ovulate at the same time, it increases the likelihood of them getting pregnant simultaneously, which might be beneficial for sharing the care of babies in a group or tribe setting.

What is phototherapy and how is it related to Seasonal Affective Disorder?

Phototherapy is the use of light exposure as a treatment for conditions like Seasonal Affective Disorder. It is based on the idea that the symptoms of SAD are related to the reduced light levels during winter months.

What are the potential confounding variables in the study of Seasonal Affective Disorder?

Potential confounding variables include increased bills for artificial light and heating, the psychological impact of Christmas and the holiday season, and lifestyle changes such as reduced outdoor activity due to cold and darkness.

Why might not everyone exposed to reduced daylight develop Seasonal Affective Disorder?

Not everyone develops Seasonal Affective Disorder because there may be genetic predispositions and underlying mental health issues that make some individuals more susceptible to the condition than others.

How does the study of pheromones relate to the synchronization of the menstrual cycle?

The study of pheromones is relevant to menstrual cycle synchronization because these chemical signals, released into the environment, can influence the internal mechanisms of others, potentially affecting their menstrual cycles.