In the United
States, daylight saving time (DST), which began Sunday, March 10, 2019,
ends Sunday November 3, 2019. On that day, at 2 a.m. local time, clocks
“fall back” one hour to 1 a.m., to what’s known as standard time
March 26, 2019, the European parliament voted to end DST as of 2021
While the
original intention was that extending daylight hours during the summer
would result in energy savings, research shows it’s not saving us any
money, and is contributing to ill health
Researchers
have noticed a statistically significant increase in the number of car
accidents, workplace injuries and heart attacks in the days after the
time changes in the spring, which appear to be related to loss of sleep
and circadian rhythm disruptions
While the most
adverse health effects are attributed to the springtime switch to DST,
the switch back to Standard Time in the fall means your body has to get
used to it getting dark earlier in the evening. Tips to help your body
adjust to the time change are included
In the United States, daylight saving
time (DST), which began Sunday, March 10, 2019, ends Sunday November 3,
2019. On that day, at 2 a.m. local time, clocks “fall back” one hour to 1
a.m., to what’s known as standard time.1,2
In Europe, clocks are rolled back an hour on the last Sunday of October, which this year falls on October 27.3 Regardless of the exact day, this time change from DST to standard time results in the gain of one hour of sleep.
While the loss or gain of one hour might sound like a negligible
amount, research clearly shows it has significant ramifications for
public health and safety — particularly after the switch to DST in the
spring. However, even the switch back to standard time can leave you
feeling off-kilter for days or even weeks, as your body adapts to the
earlier onset of darkness.
Europe Ditches DST Effective 2021
Many Europeans are now rejoicing. March 26, 2019, the European parliament voted to end DST as of 2021,4 so they only have two more years of clock-changing to deal with. As reported by The Guardian,5
member states will be allowed to “choose whether to remain on
‘permanent summer’ or ‘permanent winter’ time under the draft
directive.”
This means that countries opting to remain permanently on
“summertime” (the term used for DST in Europe) would perform their last
and final clock adjustment on the last Sunday in March 2021. For
countries opting to remain in permanent wintertime/standard time, the
final adjustment would take place on the last Sunday of October 2021.
While some U.S. states and territories have abolished DST, most have not.6 However, the tide is starting to turn even in the U.S. Each year, more states are considering taking action to end it.
As reported by National Geographic,7
dozens of state bills have been introduced in 2019, proposing various
changes to DST. Oklahoma, Texas, Kansas, California, Oregon and
Washington are all considering legislation to opt out of the time
change.
Why Do We Have DST?
As explained in the featured video, daylight saving time is intended
to give you more access to daylight hours, thereby reducing energy costs
and promoting healthy outdoor activities.
But is it worth it? Kazakhstan abolished DST as of 2005,8 citing health complications as the reason for its decision.9 In 2011, Russia’s president Dmitry Medvedev also canceled DST due to the “stress and illness” it causes.10
While the original intention was that extending daylight hours during the summer would result in energy savings,11
research shows it’s not saving us any money. For starters, lighting is
no longer the most significant portion of energy consumption, and
extending daylight hours encourages greater use of air conditioning and
heating, both of which use more energy than lighting. A study12 by Yale economist Matthew Kotchen and Laura Grant, Ph.D., concluded that:
“… contrary to the policy’s intent — DST increases residential
electricity demand. Estimates of the overall increase are approximately 1
percent, but we find that the effect is not constant throughout the DST
period. DST causes the greatest increase in electricity consumption in
the fall, when estimates range between 2 and 4 percent.”
Kotchen notes when DST begins in the spring, people are waking during
the coldest and darkest part of the day, often turning up the heat to
stay warm, and during long evening hours, more air conditioning is used,
leading to an overall higher energy use. He told The New York Times,13 “The way people use energy now is different from when daylight saving came about.”
Similarly, a 2018 meta-analysis14
of 44 different papers found that, on average, DST lowered electricity
use by a mere 0.34%. Locations further from the equator, with mild
summers and low cooling demands, may save energy, but geographical
locations closer actually use more energy during DST.
Advertisement
DST Increases Traffic Accidents
Aside from failing to provide any significant energy savings, the
biannual clock changes also have a detrimental impact on your physical
health. Between accidents and health repercussions, it seems clear DST
is actually costing more than it’s saving.
Researchers have noticed a statistically significant increase in the number of car accidents,15 workplace injuries16 and heart attacks17 in the days after the time changes in the spring, which appear to be related to loss of sleep and circadian rhythm disruptions.
According to one 2009 study,18,19,20
workplace accidents and injuries increase by 5.7%, and 67.6% more
workdays are lost as a result of injuries following the change to DST.
Ditto for traffic accidents. A 1996 study21,22 found traffic accidents rose by 8% on the Monday following the changeover to DST.
More recent research,23
published in 2018, found traffic accidents increase 16% on the first
day after DST and 12% on the second day. Fatal alcohol-related traffic
accidents also increase for the first week after setting the clocks
ahead.24
Suicide rates for men also rise in the weeks following DST.25
According to the authors, their finding “suggests that small changes in
chronobiological rhythms are potentially destabilizing in vulnerable
individuals.”
DST Raises Rates of Heart Attacks
Cardiac events
are more commonplace every Monday, greater than any other day of the
week, and are likely related to changes in sleep associated with the
transition from weekend to workday. This is known as the “Monday cardiac
phenomenon.”26 On the Monday and Tuesday following spring DST, studies27,28 show the risk is even more pronounced.
For example, a University of Alabama study29
found the number of heart attacks increased by 10% on the Monday and
Tuesday following the time change to DST in the spring, and decreased by
10% on the first Monday and Tuesday after the clocks are switched back
in the fall.
Other studies have found even larger discrepancies. For example, data
presented at the American College of Cardiology’s 63rd Annual
Scientific Session in 2014 revealed a 25% increase in heart attacks the
Monday after DST in the spring, and a 21% decrease in the fall when an
hour of sleep is regained.30 The most recent meta-analysis31 looking at this phenomenon was published in the March 2019 issue of the Journal of Clinical Medicine. Here they found:
“A significantly higher risk of AMI [acute myocardial infarction]
(Odds Ratio: 1.03 …) was observed during the two weeks following spring
or autumn DST transitions.
However, although AMI risk increased significantly after the
spring shift, the incidence of AMI during the week after winter DST
transition was comparable with control periods … Conclusion: The risk of
AMI increases modestly but significantly after DST transitions,
supporting the proposal of DST shifts discontinuation.”
Preliminary research32
presented at the 2018 American Heart Association conference found the
number of patients admitted for atrial fibrillation (irregular
heartbeat) also rises in the days after DST in the spring, from 2.56
admissions per day to 3.13 admissions.
Other Problems Attributed to DST
Researchers have also found people are less productive once DST is implemented. A 2012 National Geographic article33
quoted Till Roenneberg, a Russian chronobiologist, who said most people
show “drastically decreased productivity,” decreased quality of life,
increased illness, and are “just plain tired” in the week after DST in
the spring.
Disruptions in your sleep pattern tend to cascade throughout your
entire body. For instance, sleep helps reset your neural circuits that
are impaired during sleep deprivation. With too little sleep, your cognitive flexibility suffers.
Research34
from the University of Washington found cognitive inflexibility even
affects judges who are handing down sentences. On the Monday after DST
in the spring, longer sentences are imposed on people who have been
found guilty.
A similar negative effect has been found in students. A 2015 study35 found DST adversely affected sleep patterns of high school students and their ability to be vigilant at school.
Other data suggest it may affect academic performance. Researchers
compared 10 years of SAT scores from Indiana where only 15 of the
state's 92 counties moved their clocks forward during the study period.
The data indicated SAT scores were 16% of a standard deviation lower in
counties that adopted DST.36,37
On a side note, one reason Indiana is used as a discussion model for
DST is because it lies smack-dab between Central and Eastern time zones.
Geographically, it’s actually in the Central zone, but in 2006 it
adopted the standardized DST to align with Eastern standard time
changes.
The decision has been controversial in Indiana, where the western
part of the state wants to align with the Central zone, while the
eastern part favors aligning with Ohio’s Eastern zone.38,39
A 2019 article40
by Health.com also cites evidence linking DST to higher rates of
depression diagnoses, cluster headaches and lower success rates among
women undergoing in vitro fertilization.
The Importance of Maintaining Your Circadian Rhythm
Many of the problems attributed to the biannual time change has to do
with the fact that gaining or losing an hour of time throws off your
circadian clock. As noted in a November 2018 NPR report,41 your internal clocks aren’t easily reprogrammed, as they’re all synchronized to the 24-hour cycle of light and dark.
According to Fred Turek, director of the Center for Sleep &
Circadian Biology at Northwestern University, who is featured in the NPR
article, it takes a day or two for your body to adjust to the new time.
As noted by NPR:42
“Over the last 20 years, scientists have documented that, in
addition to the master clock in our brains, every cell in our body has a
time-keeping mechanism. These clocks help regulate important functions
such as sleep and metabolism.
And increasingly, there's evidence that when our habits — such as
when we eat and sleep — are out of sync with our internal clocks, it
can harm us. As we've reported, our bodies crave consistent routines.
When we disrupt our routines … it can increase the risk of metabolic
disease.”
That changing our clocks backward and forward affects our routines
and biological clocks is clear. The question is, would it be better to
remain in perpetual DST or in perpetual standard time? Or does it not
make a difference?
This somewhat sticky issue is addressed in a 2019 paper43
in one of my absolute favorite journals, Frontiers in Physiology. This
is one of the best reviews you will ever read about daylight saving time
and it’s free to read or download in its entirety.
The review addresses “numerous fallacies … propagated by lay people,
politicians and scientists,” and offers “suggestions of how problems
associated with DST … can be solved based on circadian biology.”
It’s a very comprehensive paper, and I recommend reading through it
if you want a more in-depth understanding of how keeping one time or the
other influences biology. Here’s an excerpt illustrating some of the
issues at hand:
“In September 2018, two sleep researchers from the University of
Salzburg claimed in an interview that there is no hard scientific
evidence against perennial DST and that the risks would be negligible.
This press release contained several statements that echo
wide-spread incorrect beliefs and is therefore an excellent substrate
for clarifying fallacies …
The press release adds that ‘… many people extensively use smart
phones or laptops shortly before they go to bed. The strong blue
components … are the true robbers of sleep. … the potential effects of
summer time can be neglected in comparison.’
Indeed, several studies have shown that the usage of artificial
light in the evening, and specifically that of electronic screens, does
‘rob’ sleep and delays the circadian clock. The second half of the
statement, however, is missing the point: the combination of nighttime
light exposure and DST is far worse than nighttime night exposure alone.
The nighttime light exposures delay the body clock in relation to
the sun clock, which translates to living further west is a time zone,
while DST advances the social clock in relation to the sun clock, which
translates into moving the time zone further east.
Thus, in DST, the two effects additively (i.e., both delaying the
body clock and advancing the social clock in relation to the sun clock)
increase SJL [social jetlag, i.e., misalignment of biological and
social time, such as discrepancy between work and free time44]
since both effects increase the difference between the mid-sleep on
work-free days (closer to the individual circadian mid-point of sleep)
and mid-sleep on workdays …
In summary, the scientific literature strongly argues against the
switching between DST and Standard Time and even more so against
adopting DST permanently.
The latter would exaggerate all the effects described above
beyond the simple extension of DST from approximately 8 months/year to
12 months/year (depending on country) since body clocks are generally
even later during winter than during the long photoperiods of summer
(with DST). Perennial DST increases SJL prevalence even more, as
described above.
A solution to the problem is shown in Figure 2C, which contains a
combination of obliterating DST (in favor of permanent Standard Time)
and reassigning countries and regions to their actual sun-clock based
time zones. Under such adjustment, social (local) clock time will match
sun clock time and therefore body clock time most closely.”
Tips to Protect Your Health During Time Switches
In addition to the strong recommendation of getting eight hours of
sleep on a consistent basis, there are some other things you can do to
mitigate the effects of the time change until the powers that be decide
to eliminate it.
While the most adverse health effects are attributed to the
springtime switch to DST, the switch back to standard time in the fall
means your body has to get used to it getting dark earlier in the
evening. When “falling back” an hour, the following tips can be helpful:45
• Gradually start going to bed earlier,
say 30 minutes earlier than usual Saturday, and another 30 minutes
earlier Sunday. This will help you get up earlier to maximize your
exposure to daylight earlier in the morning rather than later in the
evening.
Be particularly mindful of using electronic devices in the days prior to the switch-over. Research46
on teens shows that using electronics for four hours during the day can
increase your risk of needing more than an hour to fall asleep by 49%.
So, if you've ever considered "unplugging" for a day or two, the
weekend of the time change is a perfect time to turn everything off, or
cut down your use of electronics to a bare minimum so that you can
optimize your sleep. You can also consider supplementing with melatonin
if you have trouble falling asleep on an earlier schedule. • Exercise in the mornings over the weekend, in accordance with your overall level of health and fitness. • Eat dinner earlier and pay attention to
your diet, making sure you are consuming plenty of fresh, whole foods,
preferably organic, and minimal amounts of processed foods and fast
foods; keep your sugar consumption low, especially fructose. I invite
you to review our optimized nutrition plan here. • Practice good sleep hygiene, including
sleeping in complete darkness, checking your bedroom for electromagnetic
fields, and keeping your bedroom temperature cool enough for optimal
sleep. For a full report about how to maximize the quality of your
sleep, see “Sleep — Why You Need It and 50 Ways to Improve It.”
No comments:
Post a Comment