Setting clocks back linked to more car accidents

CHICAGO---Imagine if you had three clocks at your house set at different times. Chaos, right? 

But that’s what happens in our bodies when we shift back and forth from daylight saving time, which will occur again at 12 a.m. Sunday as we fall back an hour.  

Northwestern Medicine experts explain how our internal and external clocks become misaligned with every time switch, warn how the twice annual transition is linked to an increase in car accidents, impaired performance (learning, memory, attention) and health risks. When clocks are misaligned, that increases health risks like cardiovascular disease.   

Ultimately though, the fall transition is easier for people to adapt to because standard time puts those three clocks into alignment as nature intended.  

The sleep experts are neurologists Dr. Sabra Abbott, assistant professor of neurology in sleep medicine at Northwestern University Feinberg School of Medicine, and Dr. Phyllis Zee, chief of sleep medicine and director of the Center for Circadian and Sleep Medicine at Feinberg.  

Dr. Abbott: “We have three clocks that we are trying to keep aligned with each other. There is the clock in our bodies, the clock on the wall and the 'clock' of the environment (when the sun rises and sets). With the transition to and from daylight saving time, all we are doing is adjusting the clock on the wall, but our bodies still have to catch up, and the environmental clock doesn't change. Because of that, the risk for car accidents and other health problems, such as heart attacks, increases. 

“Most sleep and circadian researchers advise against switching back and forth between daylight saving time and standard time because of the associated health risks. With that in mind, there has been some push to switch to constant daylight saving time, but that puts the environmental clock further out of alignment with the internal and wall clocks. As an example, if Chicago were to adapt permanent daylight saving time, sunrise would not occur until after 8 a.m. in December. 

“The fall transition is easier for most people to adapt to compared to the spring transition, but overall is still problematic. There are studies demonstrating an increase in accidents both in the fall and spring over the weekends of the time change. From an overall health standpoint, we anticipate the greatest health benefits to come from both getting rid of the bi-yearly time changes, and keeping that time at standard time, not daylight saving time.” 

Dr. Zee: “Shifting clocks back and forth has adverse effects on the brain and body because it causes circadian rhythms to be misaligned. Even with possibly an extra hour of sleep for a day in the fall, the change in time has been associated with negative performance in learning, memory and attention.  

“There are biological clocks in most of our tissues and organs. When these clocks become out of synch with the light-dark cycle and behaviors such as feeding, exercise and sleep, research has shown that this misalignment can impair metabolic, cardiovascular and cognitive functioning.  

“The biggest threat to our health is daylight saving time. It has been linked to higher rates of obesity, diabetes and cardiovascular disease.  

“I am in favor of making standard time permanent. It will allow our internal clock to be better synchronized with the sun and the natural seasons for the majority of the year and for most of the population. It should help us be better rested, healthier, more productive and safer.”