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Literally Sick (and Tired) of Daylight Saving Time

Healthcare was at the top of many voters’ minds in last week’s election, with a range of health-related issues appearing on ballots across the country. Among other health-related measures, three states voted to expand Medicaid, Massachusetts rejected a ballot measure that would limit nurse-to-patient ratios, and Nevada exempted menstrual products from the state sales tax. But a California measure regarding daylight saving—less clearly health-related on its face—could also have some important implications for health.

Proposition 7 asked California voters whether they supported allowing the State Legislature to establish permanent, year-round daylight saving time (DST). It received about 60 percent of the votes. Following the vote, in order for California to actually end the tradition of turning clocks back in the fall and forward in the spring, the State Legislature would first have to approve this decision by a two-thirds majority. It would then need to be approved by Congress.

In support of year-round DST, State Democratic Assemblyman Kansen Chu, the bill’s sponsor, cited a 2011 study showing that the Monday and Tuesday after moving clocks forward in March is associated with a 10 percent rise in the risk of a heart attack. The research indicated the risk decreases by about 10 percent when clocks move back in the fall. A 2014 paper based on data from the Blue Cross Blue Shield of Michigan Cardiovascular Consortium database found a 24 percent increase in heart attacks on the Monday following the spring clock change, compared to other Mondays in the year, and a 21 percent decrease in heart attacks the Tuesday after the fall change.

The official argument in support of Proposition 7 that appeared in the state voter information guide also cited a study that demonstrated an 8 percent increase in stroke risk in the two days following a daylight saving time transition. The study showed that increased risk of stroke was much greater among cancer patients and people over 65 (with an increased risk of 25 percent and 20 percent, respectively) following a transition. (The study also found, however, that the frequency of stroke hospitalizations in the entire week after a DST transition wasn’t different from control weeks, indicating an effect on temporal patterns of strokes.)

Moving the clock forward in the spring has also been linked to an increase in workplace injuries, and research has demonstrated a connection between daylight saving transitions and traffic accidents.

A 2001 paper showed a significant increase in the number of fatal accidents on the Monday after moving clocks forward in the spring. While the study showed a non-significant decrease in the number of fatal accidents on the Monday following the fall change, there was a significant increase on Sunday. This supported the authors’ hypothesis that this might result from drivers anticipating the extra hour of sleep and staying out and driving later, and possibly drinking more on Saturday night. This could lead to more traffic fatalities early Sunday morning.

Other research has indicated negative effects of DST on moral decision-making and cognitive ability.

Opponents of Proposition 7 argued that year-round DST could result in more pedestrian deaths on dark winter mornings, it would put California out of sync with its neighbors, cause confusion, and reduce attention on more pressing substantive issues.

Currently, Arizona and Hawaii align with federal standard time throughout the entire year. But California isn’t alone in its efforts to impose year-round DST. Florida’s Sunshine Protection Act, which seeks to implement year-round DST, went into effect in July. However, because congressional approval is required for states to be able to impose year-round DST, and because this hasn’t happened, Florida’s still changing its clocks for now.

In March, Senator Marco Rubio introduced his own legislation (also called the Sunshine Protection Act) to make DST permanent nationwide. Greater physical fitness during DST, as well as greater physical activity among children, possibly reducing childhood obesity under permanent DST, were cited as potential benefits of the legislation.

New England has also been active in advocating to eliminate the biannual clock change. In November 2017, a Massachusetts commission released a report stating that they anticipate positive benefits from permanent DST. However, they stated that Massachusetts should only make this change if a majority of northeast states do so as well, possibly including New York. Other New England states have introduced bills as well, yet none have been enacted at this time. Time Zone Report provides information on DST-related legislation in other states.

But while most of us are likely stuck with this transition for the foreseeable future, there might be some ways to minimize the risk of dangerous DST effects. The National Sleep Foundation, for example, has suggested that sleeping in on Sunday of the spring change and taking a nap in the afternoon can be a good way to combat the transition’s effects.


Rebecca Friedman is a 2018-2019 Student Fellow at the Petrie-Flom Center.

Rebecca Friedman

Rebecca Friedman

Rebecca Friedman graduated from Harvard Law School in 2019. Prior to becoming a Student Fellow, she participated in the Health Law and Policy Clinic with HLS' Center for Health Law and Policy Innovation. At the time she completed her Fellowship, Rebecca planned to work at Charlotte Center for Legal Advocacy in Charlotte, North Carolina as an Equal Justice Works Fellow sponsored by Kilpatrick, Townsend & Stockton LLP. There, Rebecca will provide direct representation to Medicaid beneficiaries experiencing legal challenges as North Carolina transforms its Medicaid system to managed care, and will work to ensure that Medicaid beneficiaries facing legal issues as a result of social determinants of health receive appropriate support. As a Petrie Flom Center Student Fellow, Rebecca studied the potential for Medicaid to cover doula services and analyzed how racial and socioeconomic disparities in prenatal care and childbirth could be mitigated as a result. The current title of Rebecca’s paper is “The Feasibility and Potential Impact of Broader Medicaid Coverage of Doula Services on Racial and Socioeconomic Disparities in Birth Outcomes.”

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