The human body readily responds to changing environmental stresses in a variety of biological and cultural ways.
As the Baby Boomer generation was reaching voting age, Albertans endorsed daylight saving time (DST) through a referendum in 1971. The line of reasoning went like this: there would be more daylight time after a day’s work to go for a bike ride, play golf, baseball, and other summer sports. Over the past 46 years, the boomers also took advantage of the extra summer daylight to work in their yards and gardens, and to interact with their children. Any Albertan who has travelled to the Southern U.S. in June and July is shocked to find it gets dark there by 8:00 PM.
Now that the boomers are aging out and the Millennial generation has an increasing voting power, the media is hectoring us with how difficult it is to change our clocks twice a year, or how stressful it is on our bodies to adapt to a one hour change. It is implied that DST-caused sleep deprivation leads to increased accidents both vehicular and industrial. I am very concerned for people with these issues. Not only would it be extremely dangerous for them to travel even as close as British Columbia, but they must certainly not deviate from their usual bedtime on weekends lest the stress might overtake them.
Considering how dangerous that loss of an hour might be, I endeavored to learn what I could about humans and stress. Now I’m not going to attack this problem at the level of Hans Selye, the Canadian scientist credited for popularizing the word ‘stress’. I just want to know how humans adapt to the changing seasons. I also want to investigate the stress inherent in our culture of describing time. Here is what I learned:
Humans adapt to stress in a variety of ways. Long term, there is genetic change and evolution. For example, a trait enabling an advantageous response to a stress may allow an individual to survive longer and pass on that trait to the next generation. While interesting, I don’t think evolution can explain the loss of the ability to adapt to daylight saving time.
Epigenetic change has been reported to play a role in adapting to the stress of feast or famine and may even affect future generations. Can epigenetics explain the change in our ability to handle the stress of daylight saving time? I haven’t yet found any evidence of anyone working on this problem.
Humans can also adapt to stress through acclimatization. Humans adapt through physiological change to variation in temperature. Albertans are more acclimatized to living in higher altitudes than people who live in coastal British Columbia. We can feel immediate acclimatization through our ears popping when we travel over mountain passes, or take off in an airplane. As we approach the winter solstice, we are adapting to the shorter daylight times. Humans also adapt through culture and technology. Can it be that the technology of the clock can be the limiting factor for the people who wish to do away with daylight saving?
No, the real problem with the changing time seems to be related to the way we synchronize our internal clock, called circadian rhythm, with our cultural clock. Persons who are sleep deprived may have more trouble adapting to time change than healthy individuals. Overconsumption of alcohol or coffee can also influence our circadian rhythm. Light plays a role in regulating our circadian rhythm through regulation of the hormone melatonin. During the shorter days associated with the winter solstice, increased melatonin secretion makes us sleepy, or even causes symptoms of seasonal affective disorder (SAD). Some shift workers use melatonin supplements to help adjust their sleeping schedules. The potential side effects of supplemental melatonin mean it should not be taken without medical supervision.
An exciting new field, human chronogenetics, studies the genetic basis of two physiological mechanisms: homeostasis and circadian rhythm. In simple terms, chronotypes (how long have we been awake versus timing of sleep) are being subjected to genome-wide association studies. These are long term studies. I won’t be waiting for the results. I’m not worried about the health effects of either daylight saving time or of travelling eight time zones away. I’ll rely on my circadian rhythm to tell me when to sleep and when to wake up. I’ll sleep a little bit longer in the dark of winter, and be ready to take full advantage of those long summer nights that are a trademark of our country.
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