Daylight Saving Time

Last Sunday, we all switched from standard time to daylight saving time, losing an hour of sleep in the process. Should we stop this changing of clocks every six months? We have three options: 1) we can continue to switch between standard time in the winter and daylight saving time in the summer (our current practice), 2) we can change to permanent daylight saving time (a change that the Senate has passed, but has not yet been approved by the House of Representatives), or 3) we can change to permanent standard time. A position paper from the Society of Research on Biological Rhythms addresses this issue. The citation and abstract are given below.

Roenneberg T, Wirz-Justice A, Skene DJ, et al. (2019) “Why Should We Abolish Daylight Saving Time?” Journal of Biological Rhythms, Volume 34, Pages 227–230.

Local and national governments around the world are currently considering the elimination of the annual switch to and from Daylight Saving Time (DST). As an international organization of scientists dedicated to studying circadian and other biological rhythms, the Society for Research on Biological Rhythms (SRBR) engaged experts in the field to write a Position Paper on the consequences of choosing to live on DST or Standard Time (ST). The authors take the position that, based on comparisons of large populations living in DST or ST or on western versus eastern edges of time zones, the advantages of permanent ST outweigh switching to DST annually or permanently. Four peer reviewers provided expert critiques of the initial submission, and the SRBR Executive Board approved the revised manuscript as a Position Paper to help educate the public in their evaluation of current legislative actions to end DST.

Biological oscillations are complicated. Readers of Chapter 10 in Intermediate Physics for Medicine and Biology know that nonlinear dynamics makes resetting an oscillator’s phase difficult, and that driving a nonlinear oscillator can lead to complex, and sometimes even chaotic, behavior. I’m glad that the Society for Research on Biological Rhythms sought advice from experts about this issue.

Roenneberg et al.’s paper focuses on health issues related to our three clocks: the sun clock, our body clock, and our social clock (the clock set by society). The authors summarize the problem of synchronizing these three clocks in this way: 

We live according to the same social clock time within a time zone, but as long as we still can see the natural day (through windows or on our way to or from work or school), our body clocks still follow more or less the time of the sun clock.

Is this a problem? Apparently so. 

We know that DST increases the time difference between the social clock and the body clock. More and more studies show that time differences between the social clock and the body clock challenge our health, are associated with decreased life expectancy, shorten sleep, cause mental and cognitive problems, and contribute to the many sleep disturbances.

I removed the references from this quote, but the authors support these claims by citing many research studies. Note that these problems do not arise only from the change back-and-forth between standard and daylight saving time in the spring and fall. Even permanent daylight saving time would cause chronic health problems.

My preference is permanent standard time. I live in Rochester Hills, Michigan (a suburb of Detroit), which is in the western part of the Eastern Time Zone, so I was surprised to read that 

the further west people live within a time zone, the more health problems they may experience and the shorter they live on average.

Yikes! 

Michigan is also in the northern part of the United States, where differences in the length of day and night throughout the year are exaggerated compared to our southern neighbors. This year in early January the sun rose in Detroit just after 8 am. Change to year-round daylight saving time and we would have sunrise at 9 am. For a morning person like me, that’s a lot of darkness before the sun comes up. 

My personal preference, however, isn’t important. I’m sure there are others who feel just as strongly that year-round daylight saving time is better than year-round standard time. What impresses me is that Roenneberg et al. make a strong case favoring permanent standard time as being better for society overall. They conclude that

if we want to improve human health, we should not fight against our body clock, and therefore, we should abandon DST and return to Standard Time (which is when the sun clock time most closely matches the social clock time) throughout the year.

I agree!

And if Congress refuses to move to year-round standard time, I would rather keep things as they are now (changing with the seasons) rather than have year-round daylight saving time.