Charting: Follow-up - Seasonal Variations of Temperature (BBT)

Data Sample

Many members were concerned that the data sample may include people in the southern hemisphere which may skew the data. Let me put this concern to rest, the data presented only included data from the United States. It does not include data from the southern hemisphere. We also considered a larger data set and saw similar patterns. To avoid any possible confusion we decided to present only a restrictive subset.

Some members feared that we did not have enough data to show a significant plot and that a few people with abnormal temperatures may have skewed the data. The data set includes only a subset of the data we have available in order to run the calculation quickly. It however includes several hundreds of thousands of data points per months.

Yearly Pattern

This was certainly the most commented upon. I can safely say that the immense majority of members think that this is an effect of the environment. Basically most people commenting thought that the bedroom temperature and clothing/sleeping arrangement were the main drivers for the pattern we see. In the winter months most people have central heating and/or sleep under a warm comforter and wear warmer night clothing. This would tend to increase their BBT compared to summer months where people would sleep with lighter clothing and sometimes with air conditioners. This seems to be a reasonable explanation especially when you take into account that most mammal's body temperature is indeed affected slightly by the environment temperature.

Some people proposed that in addition to this a metabolism change between summer and winter months may be at play compounding the environment effect.

Others proposed that the change in daylight hours may cause some biological clock changes that may induce metabolism changes.

General Trend

Proportionally we received very few comments about this pattern of the graph. Most members thought that the downward trend was most likely related to global warming. Some people proposed that our lifestyle may be changing rapidly due to a more sedentary life. Others proposed that it may possibly be an aging issue (metabolism slows down as you age). This issue is not very clear and as at least one person mentioned it may well be something temporary in the grand scheme of things. One aspect that I tried to find out is whether it may be related to the average outdoor temperature across the United States. I tried to quickly look-up a chart and the only thing I could find quickly was this page from the search engine Wolfram Alpha. The scale of the graph though is such that it is hard to see if the trend is similar but I have the impression it is roughly similar.

In conclusion, I think that this would need more digging to really explain it perfectly however it is definitely an interesting piece of data. Thank you to those who responded with their thoughts.

To be continued...