Setting the clocks forward has me asking, what’s wrong with sun time? I hate springing forward! I hate it every year from the time it happens until we fall back to standard time.
For weeks, I feel off. My eating schedule no longer works with work day conventions. I’m not sleepy at bedtime. I’m groggy when the alarm goes off in the morning. I realize I can slowly adjust for these changes, but what are any of us gaining?
Farmers and gardeners are well aware that plants and animals respond to the sun, not what time we arbitrarily assign to its position. Cows do not care whether the clock says 5am or 6am when they are milked, but they are definitely aware if you change the interval between milkings. Why would human animals be any different?
We’re not so different. Humans have an internal circadian clock. It’s a sort of Big Ben of the mind located in the suprachiasmatic nucleus (SCN) of the hypothalamus. This master clock accounts for approximately 20,000 neurons.
According to a study on the effects of Daylight Savings Time on circadian rhythm, Circadian clocks roughly consist of a set of proteins, capable of generating self-sustained positive and negative transcriptional feedback loops with a free-running period of approximately 24 h.
This central clock can directly and indirectly influence many functions: sleep/rest and locomotor activities; eating and drinking; core body temperature; endocrine activity; metabolism; autonomic and sympathetic activity, and more.
This study looked at the possible correlation between desynchronization of an organism and its environment and the development of cardiovascular disease. Circadian clocks use daylight to attune the body to the environment. That doesn’t change when the clock changes, but because behaviors change due to the time change, the body’s systems are affected.
Cardiovascular events have been observed to follow temporal patterns across 24 hour periods. Based on observation, it has been estimated that the incidence rate of acute myocardial infarction (AMI) onset is 40% higher in a morning period than throughout the rest of the day. Rupture or dissection of aortic aneurysms also shows a circadian preference for occurrence in mornings.
The fact that greatly different vascular events have similar temporal patterns may be due to underlying mechanisms. Increased blood pressure, heart rate, sympathetic activity, basal vascular tone, and vasoconstrictive hormones exhibit circadian rhythms with phases that correlate with a larger number of cardiovascular events. So, the question is whether the change in pattern required by a shift to Daylight Savings Time increases adverse cardiovascular events?
Additional factors related to adverse events are stress and lack of sleep. Both of these follow a circadian pattern that changes with DST. Let’s say your system is attuned to the external environment and functioning well. You set the clocks forward an hour. It feels like external time has doubled so you scramble to keep up, but your rhythm is no longer in sync with the environment. This feels stressful. And you get less sleep because the change is disruptive. The kids won’t get ready on time and you feel lethargic so you don’t work out.
The authors of the study above reviewed six other studies showing an increased incidence of cardiovascular events following the spring move to DST. The increase ranged from 4 to 29% depending on the study and was more pronounced in women.
It looks like DST has a demonstrable detrimental effect on health, especially in women. We have a policy that increases risk of onset of a heart attack by up to 29%. Does that not give us pause?
In the US, we talk a lot about healthy lifestyles while enacting policies that aren’t healthy at all. Daylight Savings Time doesn’t make us healthier. It doesn’t give us more hours in the day. It doesn’t save energy. And summertime has longer evening daylight without any arbitrary moving of the clock.
Perhaps we should begin with do no harm and leave well enough alone. Seriously, what’s wrong with sun time?
