05 How Daylight Savings Affects Well-Being
Lately, I’ve been obsessed with circadian rhythms, the science of body clocks, and embodiment,
As it turns out, circadian rhythmicity is tied to interoception, one of the foundations of embodiment. Today, let’s explore the connections between them more deeply in a way that I haven’t had space to do on Instagram or in Masterclasses.
Where I live in the U.S., many of us turned the clock forward on Sunday, March 12th. Hawaii (where a chunk of my family lives), most of Arizona, Puerto Rico, the U.S. Virgin Islands, Northern Mariana Islands, Guam, and American Samoa do not change their clocks. Most of Arizona does; the Navajo Nation, which also includes parts of what is now known as Arizona, New Mexico, and Utah, do not observe the change.
These exceptions tell us a great deal, if we’re open to listening. (More about that in a bit.)
Many areas across the world, such as Africa, Asia, China, Japan, India, South America, and others also do not change their clocks.
First, a little nomenclature. The term “Daylight Saving(s) Time” refers to moving the clocks forward an hour in the spring and moving them back in the fall. The term “Daylight Standard Time,” or standard time, is the time when Daylight Saving Time is not in use.
What’s the Big Deal, Anyway? It’s Only An Hour.
Many people claim that what’s known as Daylight Saving Time (changing the clocks) isn’t a big deal. It’s like jet lag, they say—like traveling across a one-hour time zone from, say, Chicago to Boston. They say that it takes just a day or two to get over.
it’s not like jet lag at all. And it takes far longer than a couple of days to get over.
When you travel to another country, the cues about light, mealtimes, sleep, and more occur in sync with that country’s time. This makes it easier to adapt to the light, to eating, and to sleeping when you travel across time zones. But when you change the clocks artificially by an hour, the cues for light, food, and sleep stay the same; they’re synced to the sunlight. (It’s more complicated when you travel to another time zone during daylight savings, but let’s put that aside for today.) But the time itself has changed. That means you’re out of sync. Let’s look at why that matters, and why it’s not as simple to recalibrate as it is to recover from jet lag.
The Emerging Science of Chronobiology
The field of chronobiology focuses on the biological and cyclical rhythms in the body and, I’d add, the body’s relationship with time itself. Almost all species have internal rhythms and a sense of time. We have internal circadian (approximately 24-hour) clocks that generate and shape daily cycles in our physiology, emotion, and behavior.
We have ultradian rhythms, too, which occur in smaller time units like two to four hours. Our Basic Rest and Activity Cycles, stages of sleep, hormone secretion, and digestion observe these—often, in addition to circadian rhythms.
Most organisms inherit the ability to track time on this 24-hour scale. For example, bees use their clocks to visit flowers at the appropriate time of day so they can feed when flowers are open. Birds use their biological clocks during migration to compensate for the changing position of the sun throughout the day. Other mammals rely on them to forage at the ideal times for avoiding predation. Your circadian clock is always trying to figure out “when” you are in time--and along with it, how to be in the (cellular) moment.
To be in synchrony with the solar cycle ensures your health, well-being, and survival.
Without contextual information from the outer world, you have a daily rhythm that is closer to 24.2 hours. Getting sunlight adjusts your behavior to a solar day; otherwise, your rhythm would be off--in just five days, for example, you’d be off by a full hour. In one month, you’d be off a full six hours. The effects of being out of sync show up at the level of the cell, the tissue, and behavior.
Circadian Rhythms + The Body As An Organ of Perception
Homeostasis refers to the way organisms like cells, bodies, and larger systems regulate energy and maintain balance in response to a changing environment. Like interoception, the awareness of signals coming from the body, circadian rhythms are part of homeostasis and therefore essential to survival.
Here are just a few major functions that span both circadian rhythms and interoception:
Body temperature, which reaches its lowest point about two hours before awakening
Gastrointestinal function and the regulation of the enteric nervous system or belly brain
Gut microbes, which also function on an ultradian (90-minute to 4-hour) time unit
Hormone secretion, including cortisol, which peaks soon after awakening (and also includes blood sugar regulation, and the relationship between Vitamin D3 (a hormone) and melatonin)
Heart rate and cardiovascular function
Energy and fatigue
Immune cells also have a clock. Normal immune responses depend greatly on the time of day. Your ability to fight off an endotoxin depends on the time of day you come into contact with it, and the status of your immune system when you do. A time shift like daylight saving puts the body in a pro-inflammatory state, which can worsen heart disease outcome.
The spring shift forward results in less exposure to light in the morning, when we need it most. Morning is also the time when exposure to light impacts cellular signaling and circadian syncing. The time change also results in more light in the evening, when the photoreceptors in our eyes are highly sensitive to light. In the evening, light disrupts the release of natural melatonin in our bodies that would normally promote sleep. (More light in the morning, when the photoreceptors are less sensitive to it, has a less disruptive effect on sleep.) Many of the negative effects of the spring time change are intertwined with the inevitable loss of sleep it augurs. And the out-of-syncness we feel in response to springing the clocks forward lasts a full eight months in the U.S. (It ends in November, when we change the clocks back.)
In an interview with Scientific American, Beth Malow, a professor of neurology and pediatrics at Vanderbilt University, had this to say:
“Most people agree that we need to get rid of this transition back and forth. I personally am an advocate for permanent standard. The reason I am is because I look at light as really important for our well-being, our mood and our sleep. Getting enough light, especially in the winter, is critical. If we have permanent daylight saving time, I worry that come May, June, July, we’re getting too much light too late in the evening. Then we have trouble falling asleep because we don’t make [enough] natural melatonin, which requires it to be dark. To me, the beauty of the permanent standard is: you have your light in the morning in the winter, when you need it, and you have your dark in the summer, when you need it.”
Time Change and the Enteric Nervous System
The day before the time change this year, it had been getting light around 5:40, and sunrise occurred close to 6:00 a.m. When I woke up at my normal time of 5:30 a.m. this past Sunday morning (March 12th), it was completely dark outside. My plan had been to head to the harbor for a cold dip, but I meditated for a while until it was light enough to swim safely.
It’s more than being a little out of sync. The gut microbiome (think microbes and digestive juices) are released in a rhythmic way in attunement with both 4-hour and 24-hour rhythms. Digestive juices are secreted prior to when we usually eat—one reason why regular mealtimes are beneficial, because the gut can prepare for digestion.
Eating at the “standard” clock time this Sunday would mean that it was actually an hour earlier for my body and gut microbiome; I’d be eating before my digestive enzymes and microbes had prepared my gut to digest the food. This pattern continues all day; eating the final meal at night would push that meal close to bedtime, so I’d be eating (and therefore digesting) much closer to sleep. Since eating causes a small amount of “good” inflammation and raises body temperature, I’d also be interfering with the desired drop in inflammation, digestive activity, and body temperature that helps ensure deep sleep. And if that’s not enough, by going to bed later, we’re changing the quality of sleep in the first part of the night, in which the glymphatic system removes plaque from the brain.
You might be wondering how long it takes for the enteric nervous system to catch up with this change. While we don’t know for sure, we do know that digestive rhythms take more than a day to adjust—especially in someone like meith a history of inflammatory gut issues (IBS).
Tip: For that reason, for the first few days of DST, I’ve had my first meal an hour later on the clock, which feels like “normal time” to my gut. This gives my digestive system time to prepare for the food. And I’ve eaten my last meal of the day what would be about 45 minutes earlier to my gut. This is three hours before bedtime, so there’s time to digest even though the timing is off. And I’ve upped my consumption of fermented foods prior to eating. This has been a major game-changer. It has helped my digestion, but also made it possible to go to bed, and fall asleep, earlier.
Interoception occurs all the time, under the surface of our awareness. But it’s also a form of awareness. You can bring attention to the areas of circadian function in the list above, note their status in your body , and intervene in therapeutic ways.
Large-Scale Consequences of Changing to Daylight Saving Time
For the spring transition, shifting from standard time to DST correlates with multiple changes in human behavior. These include a significant increase in fatal traffic accidents (as much as 30% in the 1-2 days following the start of DST). We also see a short-term (nearly 6%) rise in workplace injuries.
After moving the clocks forward, there is also a surge in multiple illnesses. There is a 4% increase in heart attacks and symptoms such as atrial fibrillation, and a greater incidence of strokes. At the same time, there occurs a rise in missed medical appointments, as well as emergency room visits and return visits to the hospital. These changes occur only during the spring transition from standard time to DST.
As I mentioned above, moving the clocks forward causes sleep loss and a resulting sleep debt. This results in tiredness, but also problems at the cellular level. It alters gene expression in cardiac myocytes, alters the epigenetic profile of core clock genes, and increases inflammatory markers. It lowers vagal tone, which increases heart rate and blood pressure and reduces heart rate variability.
Our circadian clocks regulate mood. Daylight Saving Time increases already-existing mood disturbances, and causes a rise in suicide.
These are not minor changes. In 2020, the American Academy of Sleep Medicine (AASM) wrote a position paper that advocated for the permanent adoption of standard time, which keeps us in tune with our circadian rhythms. (This would mean doing away with Daylight Saving Time.)
“It is the position of the AASM,” they wrote, “that the U.S. should eliminate seasonal time changes in favor of a national, fixed, year-round time. Current evidence best supports the adoption of year-round standard time, which aligns best with human circadian biology and provides distinct benefits for public health and safety.”
So why, exactly, do we still have Daylight Saving Time in the U.S. and elsewhere?
A Brief History of Daylight Saving Time
Canada was the first country in the world to begin implementing Daylight Saving Time in 1908. Germany and Austria did so in 1916, to conserve coal during World War I. Britain and other countries followed. After the war ended, many countries abandoned the practice; Canada, the U.K., France, Ireland, and the U.S. did not. The practice began again more widely during World War II, again with the goal of conserving energy. Since then, there have been multiple repeals and alterations to the practice worldwide.
Since 1966, Congress has added more time—about one month every 20 years or so—to the change. In 2005, the U.S. Energy Policy Act mandated a controversial extension of one month, which began in 2007. Daylight Saving Time now begins in mid-March and extends until November. It’s a misalignment of our biological rhythms, or circadian rhythms, for eight months out of the year.
In the U.S. and Europe, several initiatives have started, or been reprised, to abolish the practice. In the U.S., however, politician Ron DeSantis is sponsoring the “Sunshine Protection Act,” a permanent adoption of Daylight Saving Time.
What underlies these initiatives, and why might they concern us? Here, we start to get into the realm of misinformation—and, perhaps, its deliberate proliferation, which is disinformation. Here’s a look under the hood.
One public misperception in the U.S. is that DST was first implemented for the benefit of farmers, as though more evening light would be a boon to agriculture. The reality: farmers have been one of the strongest anti-DST lobbying groups since the practice first began. Circadian aspects of farming, such as morning dew and the readiness of dairy cattle to for milking are linked with the sun. (Yes, milking readiness is a thing, and is tied to circadian rhythms.) Changing the time artificially forces animals to comply with human-made artificial schedules, which constitutes a lesser-known animal rights issue.
Many people claim that Daylight Savings is better for schoolchildren because they have more time to play after school. In this article on Salon, Alison Stine laments the practice of interfering with kids' sleep, pointing out that parents spend so much time and energy trying to regulate bedtime, and to wake their children up in time for school. The change, she and countless others point out, harms children and makes the too-early school time even earlier. In fact, there are initiatives worldwide to implement later start times for children and adolescents. In the U.S., California is the first state to mandate later start times, and many other states are following suit. However, it means that for several months of the year, schoolchildren are out on the streets waiting for buses in the dark, a factor with which parents are uncomfortable.
So why are we still doing Daylight Savings?
Michael Downing, a professor at Tufts University in Massachusetts, wrote the book Spring Forward: The Annual Madness of Daylight Saving Time. Downing has pointed out that from 1915 until today, the biggest proponent of DST in the U.S. has been the Chamber of Commerce. “Daylight Saving is a loser as an energy conservation plan,” he says, “but a fantastic retail spending plan.” The idea: If it’s still light when most people get off work, they’ll do more shopping (read: spending) or go to sports events on their way home or in the evening.
Sports and other businesses support this kind of spending, of course. Representatives of the golf industry, for instance, told Congress in 1986 that an extra month of extra daylight translated to as much as $400 million annually in additional sales. The sports and tourism industries favor daylight saving time, too.
The Social Context of Daylight Saving Time
Colonialism, Capitalism, and Ableism.
These studies and historical facts highlight that one of the driving forces behind daylight saving time is capitalism. The retail, tourism, and sports industries aren’t the only beneficiaries. Corporations also benefit. The development of artificial lighting and the demands of capitalism (among them, the pressure to be productive much later into the night) mean that our light exposure has increasingly diverged from the natural day and light cycles. This has consequences: A recent research study shows that adolescents with greater levels of nighttime light had a higher prevalence of mood and anxiety disorders. This occurs in adults, also.
Many religious groups have opposed daylight savings. For religious Jews, Muslims, Baha’i, and other religious minorities, it makes practices such as prayer and fasting more difficult, inconvenient with work schedules, and harder on the body. Some Muslim countries, such as Morocco, have temporarily abandoned DST during Ramadan, while Iran maintains it year-round.
And consider elders, another overlooked social group, thanks to ageism. Whenever we disrupt sleep or disrupt our circadian rhythm, it can cause increases in inflammatory markers and the stress response, which takes a toll on the immune system, the heart, and the brain. This is much harder for elders, a population also disproportionately affected by Covid-19. As we age, circadian rhythms become more out of sync, and sleep quality also declines. Elders have a harder time with daylight saving than younger people.
Those with underlying conditions—autism, ADHD, other forms of neurodivergence, and neurodegenerative conditions such as Alzheimer’s and other forms of dementia also struggle with the time change.
My take: Neurodivergent people struggle with this more not just because of the disruption in routine, but because our brains pick up on the out-of-syncness, and feel a sense of being “off."
In addition, as we’ve noted in many other columns, capitalism (particularly, racial capitalism) doesn’t just trigger the initial harm, the out-of-syncness with natural light and rhythms and the natural world around us. Marginalized folks, and those more likely to be impacted by the negative effects of climate change, food apartheid, and other forms of oppression are also less likely to be given standard daytime work shifts and more likely to work jobs that do not comply with national legal requirements for breaks.
The common story behind Hawaii’s decision to opt out of daylight saving time, which they’ve done since the 1960’s, is this: Being much further south than any of the mainland states and at a latitude close to Mexico City, there’s no significant advantage to daylight savings in Hawaii. With Hawaii near the equator, sunrise and sunset time don’t vary, and there would be less benefit to a time change.
But I don’t think that’s the whole story. In 1893 white businessmen and sugar barons, backed by the U.S. government and military, overthrew the Hawaiian monarchy. The tourism industry has exploited Hawaii’s natural resources. The U.S. military has taken ownership of approximately 25% of Oahu, and has used the island as a site for military training, target practice, and bombing. U.S. scientists have desecrated sacred sites while practicing settler science. All these factors have contributed to gentrification and poverty for Native Hawaiians.
Hawaiians have become increasingly focused on decolonial praxis as an expression of de-occupation, sovereignty, and indigeneity. And I have to imagine that staying in tune with the planet’s natural cycles, and therefore being in deeper relationship with the planet, is an important part of that.
Recommended Resource: Parts I, II, and III episodes (and all the others) of the All My Relations podcast
Sources:
Beth Malow, a professor of neurology and pediatrics at Vanderbilt University, had this to say: https://www.scientificamerican.com/article/governments-worldwide-consider-ditching-daylight-saving-time/
These include a significant increase in fatal traffic accidents: Prats-Uribe, A., Tobías, A., & Prieto-Alhambra, D. (2018). Excess Risk of Fatal Road Traffic Accidents on the Day of Daylight Saving Time Change. Epidemiology (Cambridge, Mass.), 29(5), e44–e45. https://doi.org/10.1097/EDE.0000000000000865
We also see a short-term (nearly 6%) rise in workplace injuries: Barnes, C. M., & Wagner, D. T. (2009). Changing to daylight saving time cuts into sleep and increases workplace injuries. The Journal of applied psychology, 94(5), 1305–1317. https://doi.org/10.1037/a0015320
This includes a higher risk of heart attacks: Crnko, S., Du Pré, B. C., Sluijter, J. P. G., & Van Laake, L. W. (2019). Circadian rhythms and the molecular clock in cardiovascular biology and disease. Nature reviews. Cardiology, 16(7), 437–447. https://doi.org/10.1038/s41569-019-0167-4. See also: Manfredini, R., Fabbian, F., Cappadona, R., De Giorgi, A., Bravi, F., Carradori, T., Flacco, M. E., & Manzoli, L. (2019). Daylight Saving Time and Acute Myocardial Infarction: A Meta-Analysis. Journal of clinical medicine, 8(3), 404. https://doi.org/10.3390/jcm8030404. See also: Janszky I, Ljung R. Shifts to and from daylight saving time and incidence of myocardial infarction. N Engl J Med. 2008;359(18):1966–1968. https://doi.org/10.1056/NEJMc0807104. See also: Janszky, I., Ahnve, S., Ljung, R., Mukamal, K. J., Gautam, S., Wallentin, L., & Stenestrand, U. (2012). Daylight saving time shifts and incidence of acute myocardial infarction – Swedish Register of Information and Knowledge About Swedish Heart Intensive Care Admissions (RIKS-HIA). Sleep Medicine, 13(3), 237–242. https://doi.org/10.1016/j.sleep.2011.07.019
A greater incidence of strokes: Sipilä, J. O., Ruuskanen, J. O., Rautava, P., & Kytö, V. (2016). Changes in ischemic stroke occurrence following daylight saving time transitions. Sleep medicine, 27-28, 20–24. https://doi.org/10.1016/j.sleep.2016.10.009
And symptoms such as atrial fibrillation: Chudow, J. J., Dreyfus, I., Zaremski, L., Mazori, A. Y., Fisher, J. D., Di Biase, L., Romero, J., Ferrick, K. J., & Krumerman, A. (2020). Changes in atrial fibrillation admissions following daylight saving time transitions. Sleep medicine, 69, 155–158. https://doi.org/10.1016/j.sleep.2020.01.018
A higher number of both emergency room visits and return visits to the hospital: Ferrazzi, E., Romualdi, C., Ocello, M., Frighetto, G., Turco, M., Vigolo, S., Fabris, F., Angeli, P., Vettore, G., Costa, R., & Montagnese, S. (2018). Changes in Accident & Emergency Visits and Return Visits in Relation to the Enforcement of Daylight Saving Time and Photoperiod. Journal of biological rhythms, 33(5), 555–564. https://doi.org/10.1177/0748730418791097
There occurs an increase in missed medical appointments:
Ellis, D. A., Luther, K., & Jenkins, R. (2018). Missed medical appointments during shifts to and from daylight saving time. Chronobiology international, 35(4), 584–588. https://doi.org/10.1080/07420528.2017.1417313
It alters gene expression in cardiac myocytes: Martino, T. A., Tata, N., Belsham, D. D., Chalmers, J., Straume, M., Lee, P., Pribiag, H., Khaper, N., Liu, P. P., Dawood, F., Backx, P. H., Ralph, M. R., & Sole, M. J. (2007). Disturbed diurnal rhythm alters gene expression and exacerbates cardiovascular disease with rescue by resynchronization. Hypertension (Dallas, Tex. : 1979), 49(5), 1104–1113. https://doi.org/10.1161/HYPERTENSIONAHA.106.083568
Alters the epigenetic profile of core clock genes: Malow, B. A., Veatch, O. J., & Bagai, K. (2020). Are Daylight Saving Time Changes Bad for the Brain?. JAMA neurology, 77(1), 9–10. https://doi.org/10.1001/jamaneurol.2019.3780
Increases inflammatory markers: Wright, K. P., Jr, Drake, A. L., Frey, D. J., Fleshner, M., Desouza, C. A., Gronfier, C., & Czeisler, C. A. (2015). Influence of sleep deprivation and circadian misalignment on cortisol, inflammatory markers, and cytokine balance. Brain, behavior, and immunity, 47, 24–34. https://doi.org/10.1016/j.bbi.2015.01.004
Lowers vagal tone: Grimaldi, D., Carter, J. R., Van Cauter, E., & Leproult, R. (2016). Adverse Impact of Sleep Restriction and Circadian Misalignment on Autonomic Function in Healthy Young Adults. Hypertension (Dallas, Tex. : 1979), 68(1), 243–250. https://doi.org/10.1161/HYPERTENSIONAHA.115.06847
Daylight Saving Time increases already-existing mood disturbances, and causes a rise in suicide: mood disturbances and suicide: Berk, M., Dodd, S., Hallam, K., Berk, L., Gleeson, J., & Henry, M. (2008). Small shifts in diurnal rhythms are associated with an increase in suicide: The effect of daylight saving. Sleep and Biological Rhythms, 6(1), 22–25. https://doi.org/10.1111/j.1479-8425.2007.00331.x
In 2020, the American Academy of Sleep Medicine (AASM) wrote a position paper: Rishi, M. A., Ahmed, O., Barrantes Perez, J. H., Berneking, M., Dombrowsky, J., Flynn-Evans, E. E., Santiago, V., Sullivan, S. S., Upender, R., Yuen, K., Abbasi-Feinberg, F., Aurora, R. N., Carden, K. A., Kirsch, D. B., Kristo, D. A., Malhotra, R. K., Martin, J. L., Olson, E. J., Ramar, K., Rosen, C. L., … Gurubhagavatula, I. (2020). Daylight saving time: an American Academy of Sleep Medicine position statement. Journal of clinical sleep medicine : JCSM : official publication of the American Academy of Sleep Medicine, 16(10), 1781–1784. https://doi.org/10.5664/jcsm.8780
In this article on Salon, Alison Stine laments the practice of interfering with kids' sleep: https://www.salon.com/2023/03/10/daylight-saving-time-is-proof-we-hate-parents/
In fact, there are initiatives worldwide to implement later start times for children and adolescents: Storey K. E. (2020). Later school start times for supporting the education, health, and well-being of high school students. Paediatrics & child health, 25(3), 139–142. https://doi.org/10.1093/pch/pxz055
California is the first state to mandate later start times, and many other states: https://www.npr.org/2022/07/09/1110667087/california-law-ensures-a-later-start-time-for-middle-and-high-school-students. See also: https://www.nytimes.com/2022/07/13/us/california-later-school-start-times.html
Representatives of the golf industry, for instance, told Congress in 1986: Choi, C. Q. (n.d.). Does Daylight Saving Time Conserve Energy? Scientific American. Retrieved March 14, 2023, from https://www.scientificamerican.com/article/does-daylight-saving-times-save-energy/
A recent research study shows that adolescents with greater levels of nighttime light: Paksarian, D., Rudolph, K. E., Stapp, E. K., Dunster, G. P., He, J., Mennitt, D., Hattar, S., Casey, J. A., James, P., & Merikangas, K. R. (2020). Association of Outdoor Artificial Light at Night With Mental Disorders and Sleep Patterns Among US Adolescents. JAMA psychiatry, 77(12), 1266–1275. https://doi.org/10.1001/jamapsychiatry.2020.1935