Getting to the Bottom of DST and Permanent Standard Time

See above "Chronic Disease Incidence Rate Increases" row. With this row you can make a personal assessment of the extent to which percentage of dark mornings (and their attending circadian rhythm disruptions) increase prospects of chronic disease at your location.

Without DST and improper time zones these rate increases would not exist. Nor would the huge expenses that come with increased number of cases.

With the current DST half of us, 50% of counties, are at least 5.3% off our game. That is what the table tells us. That is what the regression tells us: Y≈ 0.35*DM-0.123.

Dark mornings are defined by the percentage of days in a year with sunrises after 7:00 AM. Looking at the underlying interactive map data, we find that under natural, unadulterated conditions dark mornings in the continental United States, at the median, do not exceed 69 days, 2.3 months per year, 19% of the year — or at the absolute maximum, 37% of the year (135 days). It is only DST's misguided human intervention that now causes them to vastly exceed these levels.

The above and following graphs are divided into three sections: 1) Group A, beneath the 37% Threshold & the home for pST, 2) the "Group B Segment" between the 37% DM Threshold and the onset of inappropriate time zones, and 3) the area above TZ onset. Group B contains all values above the threshold.

The focus in the following is on the Group B Segment, which is created by DST alone. As shown in these graphs, Group A wholly contains all potential pST values. Group A, with its low incidence rates, illustrates pST's vast health superiority over DST, as the following repeatedly confirms in graphs and data for all top 14 CDC chronic disease categories.

In the interactive maps here, wherever you see days of dark mornings exceeding 37% per year, you see conditions that would not have existed in nature — the greater the departure from 37%, the greater the abnormality. (And also the greater the harm.) To function at our peak, we commonly need dark mornings to remain less than 37% annually. To our benefit, pST is always completely beneath the 37% DM Threshold.

In rank order, the following graphs cover all 14 major CDC chronic diseases with a springboard to the interactive map, which makes it possible to see how your location relates to the graphs.

At the extreme danger of choosing Permanent DST, we have here, sorted high to low, the most westerly counties in each state. Using Y≈ 0.35*DM-0.123, eighteen states are estimated to have chronic disease rates greater than 10% higher than at the threshold — fully half, at the median, exceeding 7.3%. Often with DST, DMs exceed two-thirds of the year.

Instead, by choosing Permanent Standard Time, harmful impact, in all cases, goes to trivially low levers, effectively removed, often in negative territory. The advantage for choosing pST, instead of pDST, is transformative. An aside: Those with pST greater than 37% and having modestly higher "pST Adverse Circadian Impacts" (even with standard time), are expressing the influence of improper time zones.

As it stands with DST, those of us on the western edges of time zones are being needlessly and cruelly punished. The change to pST is greatly needed.

The current DST and improper time zones have wrongly redefined the clock itself, forcing everyone’s biology to track politically constructed time standards that no longer correspond to local solar conditions. Calling this “social time” makes it sound optional or cultural, when it is in fact mandatory and imposed. DST is the dominant time in the US. It is active for two-thirds of the year. Worse, improper time zones are active for 100% of the year. By corrupting time zones and by changing clock times for long DSTs, we are now stuck with 2.5x more dark mornings than would naturally exist.

So many dark mornings being out of step with the sun's natural light-dark cycle means one thing: a large circadian burden with serious physiological disruptions. To the surprise of most of us, reduced morning sunlight carries great influence, spelled out in millions of extra patients and billions of dollars in extra chronic disease costs.

Increase_in_Harm ≈ 0.35*DM-0.123. Low DMs virtuous. High DMs harmful. This across many fields.

The data shows no program is better than the sun's natural light-dark cycle. To widely depart from it invites harm. Via circadian channels, lack of adequate morning sunlight harms our economy and increases chronic disease.

The 37% threshold provides a solid, steady, simple reference — the upper extreme limit of the natural range. With this indicator and the interactive maps, you can evaluate the impact on your county. For any county in the continental United States, 37% or fewer dark mornings per year are desirable and readily achievable.

If nationwide pST were to be implemented, all but three states (MI,IN,GA) would instantly be beneath the threshold and even they would be marginally close to it. (With a time zone fix also, their repair would be complete.)

However, in their much debilitated state with the current long DST, the 37% points and lower are now confined to the light green regions in the following interactive map.

By employing "delay" and percentage of dark mornings in a year, we provide a unified analysis of time zones and DST. "Delay" and percentage of dark mornings are measures of desynchronization. Repeatedly with this technique, it is possible to uncover the influence of DST-TZ in a wide variety of categories.

Delay=Desynchronization=Misalignment: "Delay" at your location (shown in the map table) refers to the number of minutes that sunrises and sunsets are delayed at your location because of time zone and, when designated, DST also. It indicates the degree to which we are out of sync and is closely related to percentage of dark mornings.

• Chronic Sleep Deprivation: Residents on the western edge of a time zone get less sleep, averaging nearly 20 minutes less on work nights compared to the eastern edge of the same time zone.
• Health Hazards: Misalignment between the sun (biological time) and the clock (social time) causes chronic stress. Studies have found higher rates of obesity, diabetes, heart disease, and breast cancer in these regions.
• Mental Health Disparities: The misalignment is linked to higher suicide rates and mental health issues.
• Economic Disadvantage: Studies indicate that the western edge of time zones has lower per capita income and higher health care costs, sometimes referred to as the "cost of time zone misalignment".
• Increased Risks: The phenomenon creates a "social jetlag" effect [Desynchronization], leading to lower productivity and higher risks in early-morning work.

According to your preference, the DST-TZ fix, which we will often refer to, can employ either pST or a short DST (such as a Memorial to Labor Day DST). Both have similar influence.

The program that we wrote to create the data for the three interactive maps, operates in this manner: For each of the 3,000 US counties, for each of the 365 days in a year, using NOAA methods it computes and then for each county stores the number of number of days in a year with sunrises after 7:00 AM. It does this for each of the five options, based on starting and ending dates: #1 Permanent Standard Time, #2 Memorial Day DST, #3 1966-2006 DST, #4 2007 Current DST, and #5 Permanent DST and for delay based on longitude and time zone. With this, roughly 5.5 million pieces of information support the maps [5,478,000=3000*365*5+3000].

To supplement this discussion, the excel DM spreadsheet v2.0 here provides, at a FIPS specific level, exact delays and trendline percentages of dark mornings for all counties in the continental United States. This is the only database of this kind that we are aware of. It may be useful for simulations and for exploring dark morning relationships in other national databases.

Why “Social Jet Lag” Is the Wrong Name for a Very Real Problem

Modern medicine and popular science often describe our misaligned body clocks using the phrase “social jet lag.” It sounds clever. It sounds relatable. And unfortunately, it’s deeply misleading.

For most people, jet lag means one thing:
a short-term annoyance after flying across time zones—grogginess, bad sleep, maybe a headache—something that fades after a few days.

Even medical sources agree. Jet lag is typically described as a temporary inconvenience, not a serious or lasting condition.

So here’s the problem:
what we’re experiencing at home is not jet lag.

Jet Lag Ends. Time Manipulation Doesn’t.

Jet lag happens when you move across time zones.
The body adapts.
The discomfort resolves.

But what happens when time itself is moved, and you stay put?

That’s what inappropriate time zones and DST do—especially for people living on the western edge of time zones, a phenomenon known as the Western Edge Effect. In these locations, the sun rises later by the clock, forcing millions of people to wake, work, eat, and sleep out of sync with natural light every single day.

This is not temporary.
This is not occasional.

This is chronic biological misalignment, tied directly to geography and policy.

Language Shapes Understanding — and “Social Jet Lag” Trivializes the Issue

Words matter, especially when discussing public health.
The phrase social jet lag unintentionally tells people:

• “This is minor.”
• “This is normal.”
• “This will pass.”
• “You just need to adapt.”

But chronic circadian misalignment does not pass.
It accumulates.
It affects sleep quality, metabolic health, mood, learning, productivity, and long-term disease risk.

By borrowing the language of a fleeting travel nuisance, the term shrinks a serious, population-wide issue into something dismissible.

It’s not just inaccurate—it actively undermines public understanding.

A Rhetorical Own-Goal

Using “social jet lag” in conversation is like arguing with a metaphor that shoots your case in the foot before you finish your sentence.

You’re trying to explain something persistent, structural, and imposed, while using a term that implies something temporary, optional, and self-inflicted.

One step forward.
Two steps back.

It’s a self-sabotaging choice of language.

Even Wikipedia Makes It Worse

To add to the confusion, Wikipedia redirects “social jet lag” to Delayed Sleep Phase Disorder (DSPD).

That’s not helpful—it’s disorienting.

DSPD is a clinical sleep disorder, affecting a subset of individuals.
Time-zone-induced circadian misalignment affects entire populations, regardless of diagnosis.

Conflating the two muddies the waters for casual readers and blurs the line between individual pathology and systemic time distortion.

Call It What It Is

We don’t need cute metaphors.
We need accurate language.

This issue is about delay, desynchronization, and chronic circadian misalignment caused by time policy. That misalignment damages health and the economy.

Whatever term we ultimately settle on, it should reflect three core truths:

1. It’s chronic, not temporary
2. It’s geographically imposed, not self-inflicted
3. It affects millions, not travelers passing through

Until then, “social jet lag” remains a catchy phrase that obscures more than it explains—and stands in the way of serious public discussion about how badly we’ve broken time itself.

It is hard to even imagine, but it appears that the sun's light-dark cycle is also influencing our behavior to the extent that we see more suicides with high levels of dark mornings.

Note: The data in above graph is pure, unsmoothed, centered rolling average. Each datapoint is supported by 700 counties. Source: DM spreadsheet v2.0 & http://wonder.cdc.gov/ucd-icd10-expanded.html. To reduce confounding elements, limited data to white race. 2,460 counties available and used.

Beneath the 37% Threshold the average indexed rate of suicide is 102.7. Above the threshold it is 107.5, an average difference of 4.8%. This increase is roughly in the same range as in the DM Chronic Disease Model table: Depression, 5.8% increase; Mental Health, 4.0% increase.

In these three areas, dark morning's impact on our wellbeing is plainly adverse and unnecessary.

In contrast, the graph pattern seems to suggest a noticeably protective effect when dark mornings are between 29% and 32%, a range which elsewhere we have also seen to be healthy.

• Serotonin & Dopamine Dip: Lower morning light exposure decreases the release of serotonin and hinders optimal dopamine production, affecting mood regulation and motivation.
• Melatonin Disruption: Darker mornings, coupled with increased evening light, can cause melatonin production to start later, making it harder to wake up and causing significant grogginess.
• Mental Health Effect: The abrupt, one-hour change in the spring can cause 11% more reported depressive symptoms. This happens because the internal body clock is mismatched with the external social clock.
• Physical Symptoms: The combination of sleep deprivation and lower light can lead to increased fatigue, anxiety, and, in some cases, a higher risk of accidents.
  …

• Circadian Misalignment: Irregular rhythms (e.g., night-shift work) make individuals up to 40% more likely to develop depression.
• Biological Basis: Disruptions affect cortisol levels, sleep-wake cycles, and brain neurotransmitters like serotonin.
• Time of Day: Negative mood often peaks during the biological night.
• Treatment: Correcting rhythms via light or dark therapy stabilizes mood, proving a direct causal link.

• Delayed Sunlight: People living on the western edge of a time zone experience later sunrises and sunsets.
• Chronic Jet Lag [Desynchronization]: The mismatch between local clock time and solar time causes a chronic state of, essentially, "social jet lag," which is linked to poorer mental health outcomes.

• Bidirectional Disruption: Addictive substances (alcohol, opioids, stimulants) alter the expression of "clock genes," which control the body's internal timing, leading to sleep disorders like insomnia, hypersomnia, and restless legs syndrome.
• The Vicious Cycle: Chronic circadian disruption acts as a stressor that makes individuals more vulnerable to seeking drugs for stimulation or relief, further damaging their internal clocks.
• Impact on Brain and Behavior: Drug-induced disruption of the circadian system affects reward-related pathways in the brain, particularly dopamine signaling, which drives addiction, reward-seeking, and cravings.
• Relapse Risk: Poorly regulated sleep and circadian rhythms are significant factors in high relapse rates.
• Treatment Potential: Restoring circadian rhythms through regular schedules, light therapy, and behavioral changes is emerging as a critical component in treating substance use disorders.

For teens DST-TZ is deplorable, harmful, and unnecessary. A huge gaping error.

• Circadian Rhythm Mismatch: DST forces an artificial one-hour shift that does not match the natural day-night cycle, which is difficult for children's bodies to adapt to, disrupting sleep.
• Reduced Sleep & Mood: The extended evening light can make it harder to fall asleep, reducing overall sleep duration.
• Irritability & Dysregulation: The chronic disruption of sleep patterns can lead to increased meltdowns, less patience, and general irritability in young children.

• Later Light/Darkness: Those on the western edge of a time zone experience sunrises and sunsets later than those in the east. This means children often wake and travel to school in pitch darkness, especially during winter months.
• Chronic Sleep Loss: Residents on the western edge consistently get less sleep, which can lead to higher rates of health issues over time.

DST Erodes Coherence

Question: DST creates a personal sense of constant confusion. For a human brain highly tuned to accuracy, not to be able to look out the window and tell the time is disorienting. Can you elaborate on this and its wider impact on humans in general?

ChatGPT Responded: Yes. What you’re describing touches something deeper than mere inconvenience: humans use environmental cues to orient themselves, and DST weakens one of the oldest and most reliable cues we have — the relationship between sun position and clock time.

The brain expects coherence

For most of human history, people could estimate time by looking outside:

• low morning sun = early day
• high sun = midday
• sunset glow = evening
• darkness = night/rest

Even after mechanical clocks were invented, our brains still relied on this alignment. We unconsciously compare:

• what the clock says
• how bright it is
• our internal alertness level
• what others are doing

When these signals roughly agree, life feels coherent.

DST deliberately breaks that agreement for months at a time.

Why this feels disorienting

When the clock says 7:00 AM but your senses say 6:00 AM, the brain must constantly compensate.

That creates subtle friction:

• “Why am I so tired at this hour?”
• “Why is it still dark if it’s already morning?”
• “Why does evening feel late but the clock says early?”
• “Why am I hungry/sleepy at the wrong times?”

This can produce a persistent sense of temporal mismatch — not dramatic confusion, but a low-grade cognitive burden.

The brain is constantly predicting what should happen next. DST disrupts those predictions:

• Morning light arrives later than expected
• Evening light persists later than expected
• Social schedules stay fixed while biology shifts

When prediction errors repeat daily, people often feel:

• mentally foggy
• irritable
• rushed
• less grounded
• oddly “off”

Many describe DST not as one bad day, but as weeks of feeling slightly misaligned.

Wider human impacts

1. Reduced trust in bodily signals

People may begin overriding natural cues:

• ignoring sleepiness at night because it’s still bright
• waking before the body is ready because the clock demands it
• eating by schedule instead of appetite

Over time this weakens intuitive self-regulation.

2. Chronic stress load

Small daily mismatches accumulate:

• rushed mornings in darkness
• sleep debt
• more alarm-clock dependence
• social jet lag on weekdays [Desynchronization]

Even mild chronic stress can affect mood, patience, and health.

3. Lower cognitive efficiency

Morning alertness is strongly tied to light exposure. Darker mornings can mean:

• slower wake-up
• poorer concentration
• reduced motivation
• more mistakes

4. Social fragmentation

People vary in how strongly they feel DST:

• early risers may suffer more in dark mornings
• night owls may stay up even later
• parents managing children often feel the disruption intensely

So one policy creates unequal burdens.

Why “constant confusion” is a fair phrase

It may not be conscious confusion like forgetting appointments. It is more like: a continuous mismatch between natural time, social time, and internal time. That mismatch taxes attention and well-being.

Why Standard Time often feels better

Standard Time usually restores closer alignment between:

• sunrise and morning schedules
• darkness and bedtime
• noon and solar midday
• internal rhythms and external expectations

When signals line up again, many people simply feel more normal without always knowing why.

Bottom line

DST’s largest cost may not be a single dramatic harm. It may be the daily erosion of temporal coherence — making people live by a clock that contradicts the sky and, to some extent, their biology. Humans generally function best when environmental, social, and internal time cues reinforce one another rather than compete.

Along the same lines, to the question: ”Does DST erode coherence?” Google AI Overview responded:

Yes, DST disrupts cognitive and operational coherence in several ways, particularly during the transition in the spring.

Impact on Cognitive and Biological Coherence

The one-hour shift throws off internal circadian rhythms, leading to a state of temporary "social jetlag" [Desynchronization].

• Reduced Focus: Sleep loss and disruption cause lower alertness, reduced concentration, and slower reaction times.
• Fatigue and Mental Load: The shift causes fatigue and increases the "background hum" of disorientation, reducing overall cognitive bandwidth.
• Routine Disruption: Abrupt changes break habitual, automatic behaviors (e.g., routines that keep us safe or organized), leading to lapses in judgment. …

1. Spring normally unfolds as a smooth, daily gain of morning light [shown in the graph]

• Earlier light reaching the eyes shortly after waking
• Gradual improvement in morning alertness
• A felt sense that “days are opening up”
• Emotional cues tied to renewal and momentum

2. DST abruptly erases ~60 days of progress overnight

• Darkness again
• Cold-feeling mornings
• Heavier grogginess
• A sense that spring has “stalled” or gone backward

3. The mind interprets this as seasonal disruption, not just sleep loss

• “Spring doesn’t feel real yet”
• “It still feels like winter mornings”
• “The days aren’t improving like they should”

4. Emotional and motivational effects follow the light, not the calendar

• Mood regulation
• Energy
• Motivation
• Seasonal affective symptoms

• Blunts the psychological lift of early spring
• Prolongs winter-like lethargy
• Delays the sense of renewal people expect in March

5. Western time zones feel this most strongly

• Sunrise is already late by the clock
• DST pushes usable morning light even later
• The seasonal setback is amplified

6. Evening light cannot replace the lost signal

• Advances circadian timing
• Signals seasonal progression
• Improves morning alertness

• Delays sleep
• Blurs seasonal cues
• Extends fatigue

[Word for word, the above is ChatGPT's response to the question. Separately, the graph is derived from NOAA spreadsheet. In the spring, without DST, there is a substantially linear reduction in seasonal mortality from January 28 to June 14 (138 days). More on Human Seasonal Mood here.]

DST is an impediment to commerce.

Success exists at low Dark Mornings (DM).

As shown in the graph, top cities' high population densities come with low DMs (y-axis).

In direct opposition, DST creates high DMs.

For the nation's top business locations (measured by population density, x-axis), low DMs have brought success.

Eliminating DST and improper time zones removes high DMs and gives businesses a great boost by always staying in the proven healthy, productive, success-creating region beneath the 37% DM threshold — the region that is pST's natural home, as pointed out in this graph.

Computation elementary.

Plainly put, low DMs lubricate the wheels of commerce. DST's high DMs places a drag on them.

To the question: “In the United States is population density an indicator of economic success?” Google AI Overview responds, in part:

In the United States, high population density is generally a strong indicator of economic success, acting as a catalyst for productivity, innovation, and high-quality labor. Denser, urbanized areas, such as major cities, typically exhibit higher economic growth and efficiency, attracting businesses through concentrated labor pools and knowledge spillovers.

Key aspects of this relationship include:

• Economic Drivers: High-density areas, such as metropolitan statistical areas (MSAs), often show strong associations with higher regional income and, consequently, better quality of life.
• Productivity Gains: Denser areas are generally more productive than sparsely populated ones, allowing businesses to share infrastructure and labor.
• Industry Concentration: Urban agglomerations often correlate with faster economic growth due to the concentration of jobs and industry.

…

Along the same lines with a different focus:

Population density—the number of people per unit area—functions as a measure of appeal by indicating demand for: desirable locations, economic activity, health services, education, cultural institutions, and superior access to services.

Case #1 Permanent Standard Time, % Sunrises after 7:00 AM were 28% (This corresponds to a desirability value of 114 on the index, 14 points higher than at the base value.)
Case #4 2007 Current DST, % Sunrises after 7:00 AM were 51% (This corresponds to a desirability value of 92, an Index #, 8 points lower than at the base value.)

 

Latest Winter Sunrises Vastly Later with Permanent DST
Percentile:	2.5%	10%	25%	50%	75%	90%	97.5%
Permanent DST	7:55	8:05	8:20	8:35	8:50	9:05	9:20
Current DST & Time Zones	7:05	7:20	7:30	7:45	8:00	8:10	8:20
Permanent Standard Time	6:55	7:05	7:20	7:35	7:50	8:05	8:20
Permanent Standard Time & Fixed Time Zones	6:35	6:45	7:00	7:20	7:35	7:45	8:00

• Disrupts Circadian Rhythm: DST shifts our sleep-wake cycle away from the natural sunrise and sunset, impacting our body's internal clock. This can lead to sleep disturbances, including difficulty falling asleep and waking up, which can have cascading effects on overall health.
• Increased Cardiovascular Risks: Studies have linked the transition to DST to increased cardiovascular morbidity, including a higher risk of heart attacks and strokes, and an increase in hospital admissions for irregular heartbeats.
• Sleep Deprivation and Cognitive Impairment: The misalignment with our natural sleep-wake cycle can lead to chronic sleep deprivation, which is associated with cognitive impairment, reduced productivity, and increased risk of accidents, particularly traffic accidents.
• Safety Concerns: Dark mornings, especially during winter months, pose safety risks for commuters and children going to school.
• Negative Impact on Children: Permanent DST can lead to children having to wake up in the dark for school, potentially increasing safety risks and impacting their sleep patterns and academic performance.
• Expert Consensus: Major medical and sleep organizations, such as the American Medical Association and the American Academy of Sleep Medicine, advocate for pST, citing its alignment with human circadian biology and its benefits for health and safety.

• Aligns with Circadian Rhythm: Standard Time allows for more natural light exposure in the morning, which helps regulate our sleep-wake cycle and promotes better sleep.
• Reduces Cardiovascular Risk: By promoting better sleep and reducing circadian disruption, pST may help reduce the risk of cardiovascular problems.
• Improves Cognitive Function: Adequate sleep, which is facilitated by standard time, is crucial for cognitive function, concentration, and overall well-being.
• Enhances Safety: Standard Time ensures more light in the morning, improving visibility for commuters and children going to school.

Given the question, "Excluding fatalities and excluding the transition periods, do humans have an adverse reaction to DST?" Google's AI Overview summarized:

Yes, humans can have an adverse reaction to DST even outside of the transition periods, due to the misalignment it creates between the body's internal clock and the social clock. The shift to DST in the spring pushes more daylight to the evening and reduces it in the morning, which disrupts the body's natural circadian rhythms.

How circadian misalignment affects the body

• Waking up in darkness: The lack of morning sunlight delays the signal for your body to wake up and produce cortisol, the "stress hormone" that helps you feel alert. This can lead to increased grogginess and sleepiness.
• Later melatonin release: The increased evening light from DST pushes back the production of the sleep-regulating hormone melatonin, making it harder for many people to fall asleep at their usual bedtime.
• Chronic sleep deprivation: This combination of later melatonin production and fixed social schedules (work, school) can lead to chronic sleep loss throughout the DST period.
• "Social jet lag" [Desynchronization]: Sleep experts call this ongoing misalignment between the body's internal clock and social schedules "social jet lag." It can lead to long-term health problems.

Adverse health effects linked to DST
Research shows that chronic circadian misalignment during DST is linked to a variety of long-term health issues:

• Cardiovascular disease: Studies have linked the chronic effects of DST to an increased risk of heart disease.
• Metabolic disorders: Problems like obesity and diabetes are associated with ongoing disruption to circadian rhythms.
• Mental and cognitive health: Chronic sleep loss can contribute to mood disturbances like depression and anxiety. A Stanford study found that year-round standard time would prevent more cases of depression and suicide than year-round DST.
• Digestive issues: Some studies show a link between DST and immune-related digestive problems, such as colitis.
• Lowered immunity: Insufficient and poor-quality sleep, a common side effect of DST, can weaken the immune system.
• [This PubMed abstract, shows that research also indicates that circadian disruption impacts on immunity are not merely caused by sleep deprivation, but specifically by the misalignment of the internal body clock with external time.]

Who is most affected?
The impact of DST is not uniform across the population. Some individuals, and particularly specific groups, are more vulnerable to its effects:

• "Night owls": People who naturally prefer to go to bed and wake up later often struggle more with the shift to DST.
• Western edge of a time zone: Residents on the western side of a time zone, who experience a later sunrise and sunset, may have greater circadian misalignment and higher rates of obesity, diabetes, and cardiovascular disease.
• Adolescents: Teenagers' biological clocks naturally shift toward a later sleep-wake cycle. When DST forces them to wake up even earlier for school, their sleep deprivation is significantly worsened.

Key DST Desynchronization Studies

• Circadian Mismatch & Health (Weed et al., 2025): A major Stanford Medicine analysis in the Proceedings of the National Academy of Sciences found that changing clocks twice a year disrupts circadian rhythms, leading to higher rates of stroke and obesity. It suggests that pST is healthier than either annual switching or permanent DST.
• The "Western Edge" Effect (Roenneberg et al., 2019): Studies indicate that people living on the western edge of a time zone (where the sun rises/sets up to an hour later than the center) have higher rates of cancer, obesity, diabetes, and heart attacks. This is because their social schedule is effectively forced to start earlier in the day than their biological clock prefers.
• DST and Circadian Entrainment (Kantermann et al., 2007/2008): Research, including a study of 55,000 subjects, showed that while humans adjust to the east-west progression of dawn, the human circadian system does not adapt to the artificial time change of DST in spring.
• Impact on Adolescents (Malitz, 2024; Gaski & Sagarin, 2011): Studies on DST and scholastic performance show that the 1-hour shift negatively impacts students, particularly in the western regions of time zones, with increased rates of delayed sleep phases.
• Geographical Discrepancies (Arguelles-Prieto et al., 2024): A study using wearable devices found that transitioning to DST disrupts circadian markers more than transitioning back, corroborating that the spring shift causes a 1-hour discrepancy that persists for weeks.

1. Sleep Research Society & AASM: The American Academy of Sleep Medicine (AASM) has published position papers (e.g., 2020, 2024) advocating for the elimination of DST in favor of pST, citing evidence that the latter better aligns with human biology.
2. Chronobiology Studies (Roenneberg, 2019): Work by Till Roenneberg and colleagues on "social jetlag" is fundamental to understanding how time zones that are too broad (e.g., China's single zone, or UTC+1 in Spain) create chronic, long-term desynchronization.
3. Cancer Epidemiology & Longitude (Surveillance, Epidemiology, and End Results Program data): Studies using this data show a correlation between increasing distance from the eastern border of a time zone to the western border and higher cancer rates.
4. Math/Circadian Modeling (Jewett-Forger-Kronauer model): Researchers use this model to simulate human circadian rhythms in response to light, confirming that the spring transition causes prolonged desynchronization.

• Social Jet Lag: [Desynchronization] The chronic misalignment between biological time and social time.
• Light as a Cue (Zeitgeber): The disruption of natural light cues in the morning during DST causes the body clock to remain out of sync.
• Western Edge vs. Eastern Edge: Living in the west of a time zone creates a "permanent" 1-hour delay in the biological clock compared to the east.

Google AI Overview points out that: Based on the criteria of minimizing disruptions to morning light and sleep patterns—which are critical for health and safety—the DST starting May 20 (Case 1) is generally preferable to starting on March 8 (Case 2).

• Case 1 (May 20): With sunrise occurring 8 minutes earlier over 30 days, this indicates that the natural sun clock has already advanced significantly. Starting DST now means the shift to later morning light is minor, resulting in safer morning commutes and fewer disruptions to circadian rhythms.
• Case 2 (March 8): A 42.7-minute earlier sunrise over 30 days indicates the sun is rising much later in early March relative to the clock. Starting DST this early "springs forward" too soon, causing sunrises to occur in the dark (often after 7:30 or 8:00 AM). This is associated with increased accidents and health issues.

While a May 20 start provides fewer total days of evening light, it provides a much smoother transition that aligns better with natural circadian rhythms, reducing the "jet lag" [Desynchronization] effect commonly reported with earlier March start times.

• Accelerated Aging: Misaligned rhythms, often caused by indoor lifestyles and artificial light, are associated with a roughly 30% higher mortality rate.
• Immune System Failure: Chronic misalignment weakens the immune system, causing immune senescence (early aging) and increasing vulnerability to disease.
• Molecular Impact: Solar misalignment, such as that caused by constant artificial light or shift work, damages the molecular clock and increases oxidative stress in tissues, which reduces longevity, notes NIH.
• Chronic Diseases: Disruptions to this system are tied to neurodegenerative diseases like Alzheimer's, metabolic disorders, and cancer.
  …

Yes, CDC-related health conditions and behaviors like obesity, smoking, depression, and physical activity significantly influence voting, often showing that better health and engagement in healthy habits (like activity) correlate with higher voter turnout, while poor health, depression, and smoking are linked to lower participation, impacting who votes and potentially shifting policy focus, notes research from the American Heart Association.

Key Influences on Voting Behavior:

• Obesity: Studies suggest links, with some finding higher conservative voting in areas with higher obesity rates, though the relationship is complex and varies.
   
• Smoking: Daily smokers are significantly less likely to vote, potentially due to lower political trust, affecting public health policy outcomes.
   
• Depression: Individuals with depressive symptoms have lower voting probabilities; the impact of mental health on participation is strong.
   
• Physical Activity & Overall Health: Better physical health, more physical activity, and higher self-rated health are linked to higher voter turnout, while poor health reduces it.
   
• Cognition: Health factors, including cognitive well-being, have a powerful effect on voting, similar to education levels.

Why the Connection?

• Reduced Capacity: Physical or mental limitations can make getting to polls difficult.
   
• Lower Civic Efficacy: Poor health might decrease trust in government or belief in one's ability to make a difference.
   
• Health-Driven Priorities: Ill individuals might focus more on immediate health concerns than politics, or conversely, feel their health issues need political attention, influencing their vote.
   
• Socioeconomic Factors: Health, education, income, and age are intertwined and all affect participation.

In essence, healthier individuals, especially those engaged in positive behaviors, tend to vote more, making health a significant predictor of political engagement, notes American Heart Association.

" 'Lark' and 'owl' are terms used to describe people's chronotypes, or their typical bedtime and wake-up times. Larks are people who go to bed before 11 PM and wake up before 8 AM, while owls are people who go to bed at or after 11 PM and wake up at or after 8 AM. …"

• Health: Poor. The "Spring Forward" transition is linked to immediate spikes in heart attacks, strokes, and traffic accidents. The extended duration (8 months) causes chronic sleep deprivation for many by delaying the body's release of melatonin.
• Practicality: Moderate. While it is the status quo, the biannual clock change is increasingly unpopular and costly due to lost productivity and scheduling errors.

• Health: Optimal. Medical organizations (e.g., American Academy of Sleep Medicine) favor this. It aligns the social clock with the solar clock, where solar noon is closest to 12:00. This promotes better sleep quality and metabolic health.
• Practicality: High. It eliminates the biannual shift. However, it is often resisted by the retail and tourism industries because of the loss of one hour of evening daylight in the summer.

• Health: Worst. It forces the body to stay out of sync with the sun year-round. In winter, many would commute and start school hours before sunrise, which is linked to seasonal affective disorder and cognitive impairment.
• Practicality: High. It eliminates clock changes and is popular for evening leisure. Historically, however, it fails; the U.S. tried this in 1974 but reverted within months due to public outcry over dark winter mornings.

• No Net Increase: A 2025 analysis found no evidence that DST amplifies total physical activity, with most activity simply being reallocated.
• Shift in Timing: While evening light increases, morning activity often decreases correspondingly, resulting in no net gain in active minutes.
• Declining Habits: Studies, including data from NC State News, have linked the "spring forward" transition to fewer gym visits and an increase in sedentary activities like watching television.
• Health Risks: The sleep disruption caused by the transition can lead to a decrease in energy, potentially reducing motivation for exercise.
• Mixed Results: While some studies suggest a potential increase in outdoor recreational activities, overall evidence suggests that as a public health intervention for promoting exercise, the impact is minimal or nonexistent.

• Modest Benefits for Children: Research on over 23,000 children found that longer evening daylight was associated with a "small" increase in daily physical activity, averaging roughly two additional minutes of moderate-to-vigorous exercise (a ~5% increase).
• Limited/No Impact on Adults: Studies focusing on adults have shown that while DST shifts activity from mornings to evenings, it does not necessarily increase the overall number of sessions. In some cases, adults reported fewer exercise sessions or no significant change in activity levels.
• Geographic Variability: The increased activity effect is not universal. Studies in the United States and some other regions did not find the same correlation between DST and increased exercise in children that was observed in Europe and Australia.
• Mixed Results: Analysis of Americans in the Southwest found that DST did not impact moderate-to-vigorous physical activity (MVPA).

• Circadian Disruption: The clock change causes "social jet lag," [Desynchronization] leading to decreased endurance and strength for several days, alongside increased fatigue.
• Cardiovascular and Safety Risks: Evidence indicates a rise in heart attacks, traffic accidents, and workplace injuries, particularly in the days immediately following the "spring forward" change.
• Obesity Link: Some research suggests that long-term DST is associated with increased risks of obesity and diabetes, countering the argument that it promotes a healthier, more active lifestyle.

• Medical & Scientific Organizations: The American Academy of Sleep Medicine (AASM), American Medical Association (AMA), World Sleep Society, National Sleep Foundation, and the Society for Research on Biological Rhythms.
• Advocacy Groups: The Coalition for Permanent Standard Time, which includes groups like the National PTA and National Safety Council, and Save Standard Time.
• Key Arguments: Proponents argue that standard time reduces risks to physical/mental health, improves morning commute safety, and aligns better with the sun’s position compared to DST.

Download NOAA Sunrise.xls Spreadsheet.

Download excel spreadsheet (FIPS_Delay_DST_Time_Zone_Dark_Mornings.xlsx V2.0) for delays and percentage of dark mornings for all counties in the continental United States. See formulas for delay & for estimating percentage of dark mornings.

Download fixdst.com_Interactive_maps_DM_percentages_V3.4.csv. At a FIPS specific level, this file provides primary-source, uninterpreted information, giving raw data for researchers to draw their own conclusions and to do simulations in a wide variety of fields influenced by percentage of dark mornings. This data was used to create the interactive maps and population density graphs on this page.

Download CDC Places 2024 database.

Download Lookup Table, DM & Chronic disease rates.csv.