Time to Realign: Synchronizing to Earth's Light/Dark Cycles
SleepWorld Magazine

Time to Realign: Synchronizing to Earth’s Light/Dark Cycles

In 1974, President Nixon launched a bold strategy to address the U.S. Oil Crisis. The thinking was that if Daylight Saving Time (DST) saves energy in summer, it will save more energy when extended into winter. Thus, a two-year experiment in permanent DST began—and it quickly failed. Why? Car accidents rose, several schoolchildren’s lives were lost to sleepy motorists, and the general population was unhappy about being forced to wake and start work before sunrise in the winter months. The policy was reversed in six months.1,2 If we were to consider the outcome of this policy in a clinical trial that ended 75% early due to poor outcomes, we would likely explore alternatives before doing the same thing again. This paper aims to provide the reader with an overview of DST and to propose that Standard Time (ST) be used year-round.

Four key points will be addressed in this article:

  1. A Brief History of ST and DST
  2. Claimed Benefits of DST
  3. Physiological Effects of Clock Change and DST
  4. The Scientific Consensus Moving Forward

History

The civil definition of time began with solar time, which measures the sun’s position in the sky at a specific location. When the nineteenth century introduced locomotive travel, minor differences in clocks between neighboring cities brought a practical need to standardize time across swaths of longitude. The globe was divided east-to-west into 24 zones (like segments of an orange), one for each hour. Every zone’s meridian aligns with solar time, while places to the east and west round to the nearest solar hour. Thus, the Standard Time system was introduced.1

Decades later, world war brought DST to the forefront, on the suggestion that waking ourselves earlier might reduce evening energy consumption and aid wartime conservation. Farmers opposed DST’s disconnection from nature, but the golf industry and retailers promoted its illusion of extended daylight to increase evening revenue.3

DST’s Claimed Benefits

By the irrevocable nature of astronomy, the sun rises earlier in summer, while most of us are healthfully sleeping. The rationale for adopting DST is the following: What if we turned clocks forward an hour to wake the population earlier and maximize after-work daylight?1,3

Decades of debate have followed, to the confusion of nearly all involved. The topic of time itself can be challenging to conceptualize. Emotions often enter, as it is easy to associate DST with summer’s warmth, light, and leisure. Even the name “Daylight Saving” sounds positive on its face.1-5

In addition to supposed energy savings, various other benefits are often suggested, including the possibility of reduced evening accidents and crime, increased evening exercise, and a stimulated economy, but when each of these is examined, they either prove false or have the opposite effect.3,5-7

Simply shifting activities between morning and evening does not change the net amount of said activities. However, the effects of continually waking ourselves earlier than we are naturally inclined and exposing ourselves to more evening sunlight than is seasonally appropriate are far more likely to harm our health, mood, and performance, with connected costs to safety, education, and the economy.1,4,8- 10

Daylight duration is always shorter in winter and longer in summer, regardless of what we legislate.3 Our bodies adapt to the seasons by needing more sleep in winter and less in summer. Still, we do not adapt to DST.6 Indeed, the increased exposure to evening light compounded by the earlier wake time is another way DST makes it harder for us to fall asleep and harder to wake in the morning.5,6

The Circadian Connection

Interestingly, ST better aligns with human circadian rhythms and the natural rhythm of Earth’s light/dark cycles. A significant body of literature points to the negative impacts of DST—not only on the individual but on society as a whole. These are particularly prevalent during the acute transition from ST to DST each spring, but they persist chronically as DST (the misaligned clock) is maintained.5,11

Let us take a quick look at the problems a human may encounter during the DST transition, i.e., one fewer hour of sleep. These include an increase in acute myocardial infarction,12 inflammatory bowel disease,13 stroke,14 accidents,15 and poorer life satisfaction.11

Now, let us look at the picture of society as a whole. Other than perhaps the few industries of golf, brick-and-mortar retail, and tourism, society does not benefit from DST.6 The data show that productivity declines,4,10 school performance suffers,8,16 traffic and workplace accidents rise,9,17 and illnesses increase (including cancer,18,19 heart disease,20 obesity,21 and depression14). And all of these harms have associated financial costs21,22. There is also likely a time-zone-effect phenomenon associated with sleep deprivation and circadian misalignment in motor vehicle accidents.15

The design of DST is to force earlier waking, which is at odds with biologists’ recommendation to start school and work later.16 Most start each morning at 8:00, and many begin at 7:30 or even 7:00 (especially among lower-income populations).23-25 By turning clocks forward from ST to DST, an 8:00 start time per the social clock becomes a 7:00 start time per the sun and body clocks. DST worsens our nation’s sleep deprivation epidemic, while permanent ST would improve it.16

See how many mornings DST darkens in your city with this interactive tool: https://savestandardtime.com/chart/

Sleep and DST

The loss of one hour of sleep during the onset of DST is dreaded by many.11 It is not just that we must awaken one hour earlier, but that our circadian alignment with the sun clock has been chronically disrupted, leaving us socially jet-lagged.10 A study in the last decade found that both the fall and spring changing of clocks significantly decreased sleep efficiency and increased sleep fragmentation, and that the spring transition may cause extended phase delay.26 A more recent study, conducted with individuals using wearable devices, demonstrated a continued reduction in sleep over the week following the change to DST and less heart-rate variability during the night.27

Importantly, this reduction in sleep can result in safety-related incidents (SRI). Over an eight-year assessment period, a significant increase in SRI was found the week after DST initiation each spring, while a similar increase was not found during the return to ST each fall.28 Morning daylight is one of the strongest cues for the circadian rhythm to reset our internal clocks each day. DST trades our morning daylight away to our evenings, which results in phase delay for many.4

The bottom line when it comes to sleep is that even a one-hour shift can result in a lack of restful and restorative sleep, which extends into the week following the time shift. Attention to getting enough sleep and morning sun should be a priority.4,11

Elimination of Clock Change and of DST

In 2019 and 2020, the American Academy of Sleep Medicine (AASM) commissioned a U.S. survey to examine this issue. These surveys support that most people feel tired after DST begins (55% of those surveyed), and further, most would support eliminating the clock change (63% of those surveyed).8AP–NORC also found in 2019 and again in 2021 that more Americans would rather see ST made permanent than DST (40% to 31% in 2019 and 43% to 32% in 2021).29-30

Since 2018, dozens of scientific and professional societies worldwide have issued position statements in opposition to DST and in support of permanent ST, including the AASM, the Society for Research on Biological Rhythms (SRBR), the National Sleep Foundation, the National PTA, the Canadian Sleep Society, the Canadian Society for Chronobiology, the Society for Light Treatment & Biological Rhythms, the European Biological Rhythms Society, and the European Sleep Research Society.8,9,10,31-33

Arizona, Hawaii, and all permanently inhabited U.S. territories do not observe DST. They are on permanent ST, and their residents do not seem any worse off because of it. In all likelihood, they may have healthier sleep and outcomes than those in other locations, based on recent research in this topic.4,6

Canadian provinces are now discussing ending the clock change.5,9,32 The European Union expressed its intention to ban the practice, following a survey that found 84% of people oppose the biannual ritual.6,33 Russia relatively recently abolished its clock changes for permanent DST, which it soon reversed to permanent ST following health and safety complaints.4,20 Brazil and Samoa very recently abolished the practice in favor of permanent ST.34,35

Even with all these countries recognizing the harms of DST, and nearly five decades after Nixon’s trial of the policy, some individuals and industries still suggest instituting DST year-round. These include several state legislators and members of Congress (in the form of bills known as “Sunshine Protection”)1,3,6 and a few lobbyists from retail, golf, and tourism.6,36 Thankfully, we now have a growing group of advocates for health, safety, and education who support permanent ST, such as the National PTA, the National Safety Council, and many societies for sleep health (as noted above).8

Conclusion

Few deny that the “spring forward” to DST fatigues needlessly and endangers the population on the whole; few remember why we engage in the practice, and few support its continuance. Lay opinions vary on which clock might be preferable, though more people appear to favor ST over DST. History shows permanent DST is rarely sustainable. And finally, scientific data support ST as the healthier and safer clock for permanent usage.

An end to biannual clock change is soon upon us. What remains is the decision of which clock to keep. Permanent DST has been tried and reverted before, and not without cost. Let us make sure we get it right this time, with the clock defined by nature: permanent ST.

By Jay Pea, BA and Robyn Woidtke, MSN, RN, RPSGT, CCSH

This article originally appeared in SleepWorld Magazine Jan/Feb 2022.

Source: SleepWorld Magazine

More Information

References

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