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Daylight Saving Time: Saving light but endangering health
The American Academy of Sleep Medicine recently published its position statement reaffirming its support of utilizing permanent Standard Time (ST) as opposed to Daylight Saving Time (DST).1 DST usually occurs on the second Sunday in March when we “spring forward” by advancing the clock by 1 hour. The analogous “fall back” on the first Sunday in November refers to reversion back to the original ST, which is more synchronous with the sun’s natural pattern of rise and fall.
The earliest argument for DST practice dates back to the 1700s when Benjamin Franklin wrote a satirical piece in the Journal of Paris suggesting that advancing the clock to rise earlier in the summer would lead to economization in candle usage and save significant resources for Parisians. The modern version of this assertion infers that increased daylight in the evening will lead to increased consumer activity and work productivity with consequent economic benefits. Interestingly, the adoption of DST has demonstrated the opposite—a reduction in work productivity and economic losses.2 Another often-cited claim is that increased daylight in the evening could lead to fewer motor vehicle accidents. However, the reality is that DST is associated with more frequent car accidents in the morning.
The greatest drawback of DST is that, initially, it leads to sleep deprivation and chronically drives asynchronization between the circadian clock and the social clock. Humans synchronize their internal clock based on several factors, including light, temperature, feeding, and social habits. However, light is the strongest exogenous factor that regulates the internal clock. Light inhibits secretion of melatonin, an endogenous hormone that promotes sleep onset. While there is some individual variation in circadian patterns, exposure to bright light in the morning leads to increased physical, mental, and goal-directed activity.
Conversely, darkness or reduced light exposure in the evening hours promotes decreased activity and sleep onset via melatonin release. DST disrupts this natural process by promoting increased light exposure in the evening. This desynchronizes solar light from our internal clocks, causing a relative phase delay. Acutely, patients experience a form of imposed social jet lag. They lose an hour of sleep due to diminished sleep opportunity, as work and social obligations are typically not altered to allow for a later awakening. With recurrent delays, this lends to a pattern of chronic sleep deprivation which has significant health consequences.
Losing an hour of sleep opportunity as the clock advances in spring has dire consequences. The transition to DST is associated with increased cardiovascular events, including myocardial infarction, stroke, and admissions for acute atrial fibrillation.3 4 5 A large body of work has shown that acute reduction of sleep is associated with higher sympathetic tone, compromised immunity, and increased inflammation. Further, cognitive consequences can ensue in the form of altered situational awareness, increased risky behavior, and worse reaction time—which manifest as increased motor vehicle accidents, injuries, and fatalities.6 Emergency room visits and bounce-back admissions, medical errors and injuries, and missed appointments increase following the switch to DST.7 Psychiatric outcomes, including deaths due to suicide and overdose, are worse with the spring transition.8
Is the problem with DST merely limited to springtime, when we lose an hour of sleep? Not quite. During the “fall back” period, despite theoretically gaining an hour of sleep opportunity, people exhibit evidence of sleep disruption, psychiatric issues, traffic accidents, and inflammatory bowel disease exacerbations. These consequences likely stem from a discordance between circadian and social time, which leads to an earlier awakening based on circadian physiology as opposed to the clock time.
The acute impact of changing our sleep patterns during transitions in clock time may be appreciated more readily, but the damage is much more insidious. Chronic exposure to light in the late evening creates a state of enhanced arousal when the body should be winding down. The chronic incongruency between clock and solar time leads to dyssynchrony in our usual functions, such as food intake, social and physical activity, and basal temperature. Consequently, there is an impetus to fall asleep later. This leads to an accumulation of sleep debt and its associated negative consequences in the general, already chronically sleep-deprived population. This is especially impactful to adolescents and young adults who tend to have a delay in their sleep and wake patterns and, yet, are socially bound to early morning awakenings for school or work.
The scientific evidence behind the health risk and benefit profile of DST and ST is incontrovertible and in favor of ST. The hallmark of appropriate sleep habits involves consistency and appropriate duration. Changing timing forward or backward increases the likelihood of an alteration of the baseline established sleep and circadian consistency.
Unfortunately, despite multiple polls demonstrating the populace’s dislike of DST, repeat attempts to codify DST and negate ST persist. The latest initiative, the Sunshine Protection Act, which promised permanent DST, was passed by the US Senate but was thankfully foiled by Congress in 2022. The act of setting a time is not one that should be taken lightly or in isolation because there are significant, long-lasting health, safety, and socioeconomic consequences of this decision. Practically, this entails a concerted effort from all major economies since consistency is essential for trade and geopolitical relations. China, Japan, and India don’t practice DST. The European Parliament voted successfully to abolish DST in the European Union in 2019 with a plan to implement ST in 2021. Implementation has yet to be successful due to interruptions from the COVID-19 pandemic as well as the current economic and political climate in Europe. Political or theoretical political victories should not supersede the health and safety of an elected official’s constituents. As a medical community, we should continue to use our collective voice to encourage our representatives to vote in ways that positively affect our patients’ health outcomes.
References:
1. Rishi MA, et al. JCSM. 2024;20(1):121.
2. Gibson M, et al. Rev Econ Stat. 2018;100(5):783.
3. Jansky I, et al. N Engl J Med. 2008;359(18):1966.
4. Sipilia J, et al. Sleep Med. 2016;27-28:20.
5. Chudow JJ, et al. Sleep Med. 2020;69:155.
6. Fritz J, et al. Curr Biol. 2020;30(4):729.
7. Ferrazzi E, et al. J Biol Rhythms. 2018;33(5):555-564.
8. Berk M, et al. Sleep Biol Rhythms. 2008;6(1):22.
The American Academy of Sleep Medicine recently published its position statement reaffirming its support of utilizing permanent Standard Time (ST) as opposed to Daylight Saving Time (DST).1 DST usually occurs on the second Sunday in March when we “spring forward” by advancing the clock by 1 hour. The analogous “fall back” on the first Sunday in November refers to reversion back to the original ST, which is more synchronous with the sun’s natural pattern of rise and fall.
The earliest argument for DST practice dates back to the 1700s when Benjamin Franklin wrote a satirical piece in the Journal of Paris suggesting that advancing the clock to rise earlier in the summer would lead to economization in candle usage and save significant resources for Parisians. The modern version of this assertion infers that increased daylight in the evening will lead to increased consumer activity and work productivity with consequent economic benefits. Interestingly, the adoption of DST has demonstrated the opposite—a reduction in work productivity and economic losses.2 Another often-cited claim is that increased daylight in the evening could lead to fewer motor vehicle accidents. However, the reality is that DST is associated with more frequent car accidents in the morning.
The greatest drawback of DST is that, initially, it leads to sleep deprivation and chronically drives asynchronization between the circadian clock and the social clock. Humans synchronize their internal clock based on several factors, including light, temperature, feeding, and social habits. However, light is the strongest exogenous factor that regulates the internal clock. Light inhibits secretion of melatonin, an endogenous hormone that promotes sleep onset. While there is some individual variation in circadian patterns, exposure to bright light in the morning leads to increased physical, mental, and goal-directed activity.
Conversely, darkness or reduced light exposure in the evening hours promotes decreased activity and sleep onset via melatonin release. DST disrupts this natural process by promoting increased light exposure in the evening. This desynchronizes solar light from our internal clocks, causing a relative phase delay. Acutely, patients experience a form of imposed social jet lag. They lose an hour of sleep due to diminished sleep opportunity, as work and social obligations are typically not altered to allow for a later awakening. With recurrent delays, this lends to a pattern of chronic sleep deprivation which has significant health consequences.
Losing an hour of sleep opportunity as the clock advances in spring has dire consequences. The transition to DST is associated with increased cardiovascular events, including myocardial infarction, stroke, and admissions for acute atrial fibrillation.3 4 5 A large body of work has shown that acute reduction of sleep is associated with higher sympathetic tone, compromised immunity, and increased inflammation. Further, cognitive consequences can ensue in the form of altered situational awareness, increased risky behavior, and worse reaction time—which manifest as increased motor vehicle accidents, injuries, and fatalities.6 Emergency room visits and bounce-back admissions, medical errors and injuries, and missed appointments increase following the switch to DST.7 Psychiatric outcomes, including deaths due to suicide and overdose, are worse with the spring transition.8
Is the problem with DST merely limited to springtime, when we lose an hour of sleep? Not quite. During the “fall back” period, despite theoretically gaining an hour of sleep opportunity, people exhibit evidence of sleep disruption, psychiatric issues, traffic accidents, and inflammatory bowel disease exacerbations. These consequences likely stem from a discordance between circadian and social time, which leads to an earlier awakening based on circadian physiology as opposed to the clock time.
The acute impact of changing our sleep patterns during transitions in clock time may be appreciated more readily, but the damage is much more insidious. Chronic exposure to light in the late evening creates a state of enhanced arousal when the body should be winding down. The chronic incongruency between clock and solar time leads to dyssynchrony in our usual functions, such as food intake, social and physical activity, and basal temperature. Consequently, there is an impetus to fall asleep later. This leads to an accumulation of sleep debt and its associated negative consequences in the general, already chronically sleep-deprived population. This is especially impactful to adolescents and young adults who tend to have a delay in their sleep and wake patterns and, yet, are socially bound to early morning awakenings for school or work.
The scientific evidence behind the health risk and benefit profile of DST and ST is incontrovertible and in favor of ST. The hallmark of appropriate sleep habits involves consistency and appropriate duration. Changing timing forward or backward increases the likelihood of an alteration of the baseline established sleep and circadian consistency.
Unfortunately, despite multiple polls demonstrating the populace’s dislike of DST, repeat attempts to codify DST and negate ST persist. The latest initiative, the Sunshine Protection Act, which promised permanent DST, was passed by the US Senate but was thankfully foiled by Congress in 2022. The act of setting a time is not one that should be taken lightly or in isolation because there are significant, long-lasting health, safety, and socioeconomic consequences of this decision. Practically, this entails a concerted effort from all major economies since consistency is essential for trade and geopolitical relations. China, Japan, and India don’t practice DST. The European Parliament voted successfully to abolish DST in the European Union in 2019 with a plan to implement ST in 2021. Implementation has yet to be successful due to interruptions from the COVID-19 pandemic as well as the current economic and political climate in Europe. Political or theoretical political victories should not supersede the health and safety of an elected official’s constituents. As a medical community, we should continue to use our collective voice to encourage our representatives to vote in ways that positively affect our patients’ health outcomes.
References:
1. Rishi MA, et al. JCSM. 2024;20(1):121.
2. Gibson M, et al. Rev Econ Stat. 2018;100(5):783.
3. Jansky I, et al. N Engl J Med. 2008;359(18):1966.
4. Sipilia J, et al. Sleep Med. 2016;27-28:20.
5. Chudow JJ, et al. Sleep Med. 2020;69:155.
6. Fritz J, et al. Curr Biol. 2020;30(4):729.
7. Ferrazzi E, et al. J Biol Rhythms. 2018;33(5):555-564.
8. Berk M, et al. Sleep Biol Rhythms. 2008;6(1):22.
The American Academy of Sleep Medicine recently published its position statement reaffirming its support of utilizing permanent Standard Time (ST) as opposed to Daylight Saving Time (DST).1 DST usually occurs on the second Sunday in March when we “spring forward” by advancing the clock by 1 hour. The analogous “fall back” on the first Sunday in November refers to reversion back to the original ST, which is more synchronous with the sun’s natural pattern of rise and fall.
The earliest argument for DST practice dates back to the 1700s when Benjamin Franklin wrote a satirical piece in the Journal of Paris suggesting that advancing the clock to rise earlier in the summer would lead to economization in candle usage and save significant resources for Parisians. The modern version of this assertion infers that increased daylight in the evening will lead to increased consumer activity and work productivity with consequent economic benefits. Interestingly, the adoption of DST has demonstrated the opposite—a reduction in work productivity and economic losses.2 Another often-cited claim is that increased daylight in the evening could lead to fewer motor vehicle accidents. However, the reality is that DST is associated with more frequent car accidents in the morning.
The greatest drawback of DST is that, initially, it leads to sleep deprivation and chronically drives asynchronization between the circadian clock and the social clock. Humans synchronize their internal clock based on several factors, including light, temperature, feeding, and social habits. However, light is the strongest exogenous factor that regulates the internal clock. Light inhibits secretion of melatonin, an endogenous hormone that promotes sleep onset. While there is some individual variation in circadian patterns, exposure to bright light in the morning leads to increased physical, mental, and goal-directed activity.
Conversely, darkness or reduced light exposure in the evening hours promotes decreased activity and sleep onset via melatonin release. DST disrupts this natural process by promoting increased light exposure in the evening. This desynchronizes solar light from our internal clocks, causing a relative phase delay. Acutely, patients experience a form of imposed social jet lag. They lose an hour of sleep due to diminished sleep opportunity, as work and social obligations are typically not altered to allow for a later awakening. With recurrent delays, this lends to a pattern of chronic sleep deprivation which has significant health consequences.
Losing an hour of sleep opportunity as the clock advances in spring has dire consequences. The transition to DST is associated with increased cardiovascular events, including myocardial infarction, stroke, and admissions for acute atrial fibrillation.3 4 5 A large body of work has shown that acute reduction of sleep is associated with higher sympathetic tone, compromised immunity, and increased inflammation. Further, cognitive consequences can ensue in the form of altered situational awareness, increased risky behavior, and worse reaction time—which manifest as increased motor vehicle accidents, injuries, and fatalities.6 Emergency room visits and bounce-back admissions, medical errors and injuries, and missed appointments increase following the switch to DST.7 Psychiatric outcomes, including deaths due to suicide and overdose, are worse with the spring transition.8
Is the problem with DST merely limited to springtime, when we lose an hour of sleep? Not quite. During the “fall back” period, despite theoretically gaining an hour of sleep opportunity, people exhibit evidence of sleep disruption, psychiatric issues, traffic accidents, and inflammatory bowel disease exacerbations. These consequences likely stem from a discordance between circadian and social time, which leads to an earlier awakening based on circadian physiology as opposed to the clock time.
The acute impact of changing our sleep patterns during transitions in clock time may be appreciated more readily, but the damage is much more insidious. Chronic exposure to light in the late evening creates a state of enhanced arousal when the body should be winding down. The chronic incongruency between clock and solar time leads to dyssynchrony in our usual functions, such as food intake, social and physical activity, and basal temperature. Consequently, there is an impetus to fall asleep later. This leads to an accumulation of sleep debt and its associated negative consequences in the general, already chronically sleep-deprived population. This is especially impactful to adolescents and young adults who tend to have a delay in their sleep and wake patterns and, yet, are socially bound to early morning awakenings for school or work.
The scientific evidence behind the health risk and benefit profile of DST and ST is incontrovertible and in favor of ST. The hallmark of appropriate sleep habits involves consistency and appropriate duration. Changing timing forward or backward increases the likelihood of an alteration of the baseline established sleep and circadian consistency.
Unfortunately, despite multiple polls demonstrating the populace’s dislike of DST, repeat attempts to codify DST and negate ST persist. The latest initiative, the Sunshine Protection Act, which promised permanent DST, was passed by the US Senate but was thankfully foiled by Congress in 2022. The act of setting a time is not one that should be taken lightly or in isolation because there are significant, long-lasting health, safety, and socioeconomic consequences of this decision. Practically, this entails a concerted effort from all major economies since consistency is essential for trade and geopolitical relations. China, Japan, and India don’t practice DST. The European Parliament voted successfully to abolish DST in the European Union in 2019 with a plan to implement ST in 2021. Implementation has yet to be successful due to interruptions from the COVID-19 pandemic as well as the current economic and political climate in Europe. Political or theoretical political victories should not supersede the health and safety of an elected official’s constituents. As a medical community, we should continue to use our collective voice to encourage our representatives to vote in ways that positively affect our patients’ health outcomes.
References:
1. Rishi MA, et al. JCSM. 2024;20(1):121.
2. Gibson M, et al. Rev Econ Stat. 2018;100(5):783.
3. Jansky I, et al. N Engl J Med. 2008;359(18):1966.
4. Sipilia J, et al. Sleep Med. 2016;27-28:20.
5. Chudow JJ, et al. Sleep Med. 2020;69:155.
6. Fritz J, et al. Curr Biol. 2020;30(4):729.
7. Ferrazzi E, et al. J Biol Rhythms. 2018;33(5):555-564.
8. Berk M, et al. Sleep Biol Rhythms. 2008;6(1):22.