Health and legal time

Poor sleep is becoming increasingly prevalent and is associated with adverse health outcomes. Sunlight exposure may improve sleep by regulating circadian rhythms, increasing vitamin D, and influencing melatonin production. However, research on the sunlight-sleep association is li…

Poor sleep is becoming increasingly prevalent and is associated with adverse health outcomes. Sunlight exposure may improve sleep by regulating circadian rhythms, increasing vitamin D, and influencing melatonin production. However, research on the sunlight-sleep association is limited, especially outside of cross-sectional designs. This study examined associations between daily self-reported sunlight exposure and next-night sleep quality in 103 adults for up to 70 days. The timing of sunlight exposure predicted next-night sleep quality. Specifically, morning sunlight exposure, relative to no sunlight, predicted better sleep quality based on responses to the brief Pittsburg Sleep Quality Index. Duration of sunlight exposure was generally not associated with sleep quality. Morning sunlight may regulate circadian rhythms, subsequently improving sleep. Findings have potential implications for sleep interventions and daylight savings time policies. Future research should test whether morning sunlight exposure can enhance the effectiveness of sleep interventions.

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The study’s findings about the potential importance of sunlight exposure raise questions about the already controversial practice of daylight savings—carried out mostly in Western/Northern countries—which involves shifting clocks forward 1 hour during the warmer months so that darkness falls at a later time in the evenings (Rishi et al., 2020). Most concerns about daylight savings relate to its negative impacts on shifts in sleep timing and health, ranging from increased heart attacks to car accidents (Fritz et al., 2020; Roenneberg et al., 2019). Depending on the latitude, daylight savings might make obtaining sunlight exposure in the morning during warmer months more difficult because the sun rises later. The present findings may provide additional support for eliminating daylight savings (Roenneberg et al., 2019).

Daylight Saving Time (DST) is the practice of setting the clocks one hour forward from Standard Time (ST) in the spring and back again to ST in the fall. This commentary discusses the impact of bi-annual time changes on sleep and circadian rhythms and suggests avenues to minimize…

Daylight Saving Time (DST) is the practice of setting the clocks one hour forward from Standard Time (ST) in the spring and back again to ST in the fall. This commentary discusses the impact of bi-annual time changes on sleep and circadian rhythms and suggests avenues to minimize negative outcomes on the well-being of Canadian citizens. Ideally, ST should be close to solar time, meaning that daylight is equally distributed before and after noon time, i.e., when the sun is at its highest point in the sky. In Canada, some provinces are proposing to opt out of DST to either return to constant ST throughout the year or to implement permanent DST. National and international associations of clinicians and researchers on sleep and biological rhythms and in health sciences have positioned themselves in favour of permanent ST. In Canada, the Canadian Sleep Society and the Canadian Society for Chronobiology have also issued such a position. This commentary focuses on the implications of previous research findings for sleep and health in Canada given its northern geographical location. It concludes with a research agenda focusing on the Canadian context.

The Uniform Time Act of 1966 in the United States requires local clocks to change between standard time (ST) and daylight saving time (DST) in the spring and fall. This biannual clock change is unpopular. According to the 2021 Sleep in America Poll, a nationally representative po…

The Uniform Time Act of 1966 in the United States requires local clocks to change between standard time (ST) and daylight saving time (DST) in the spring and fall. This biannual clock change is unpopular. According to the 2021 Sleep in America Poll, a nationally representative poll administered by the National Sleep Foundation, approximately 75% of Americans reported a preference for doing away with the biannual switching in favor of year-round consistent time.1 While many agree that the clock changes should end, the question of whether to adopt permanent ST (pST) or permanent DST (pDST) remains controversial.
Scientific evidence demonstrates that the spring transition to DST wreaks havoc on human biology, resulting in more heart at- tacks,2 strokes,3 and motor vehicle crashes.4 pDST is the equivalent of moving clocks one-time zone to the east without changing the timing of sunlight, pushing self-selected bedtimes later while waking times for work/school schedules are fixed, resulting in sleep loss and its associated negative effects on health.2,3,6,7 There is also evidence of negative safety, economic, and energy effects.8,9
These pDST-associated risks led the American Academy of Sleep Medicine, National Sleep Foundation,11 American Medical Association and multiple other scientific organizations, to advocate for pST. On March 9, 2022, the US House of Representatives Energy and Commerce subcommittee held hearings about the issue and decided more information was required before a vote. In contrast, the Sunshine Protection Act (SPA, bill #S.623) that would institute pDST, quickly passed the Senate on March 15, 2022, after several senators spoke, but without any debate or dissenting vote.
We used qualitative methods to analyze the arguments made by senators about the SPA to explore the extent to which arguments were research-related or non-research-related, and within each domain, the nature of supporting arguments for pDST made by senators. We obtained transcripts from the Senate session during which the SPA (bill #S.623) passed on March 15, 2022. Transcripts were obtained from the Cable-Satellite Public Affairs Network.14 We used qualitative thematic analysis in accordance with the constant comparative method of qualitative inquiry.15 Our aim was to identify the key arguments relating to the SPA. Specifically, we analyzed the transcripts using the constant comparative method with the aim of identifying the most common research and non-research-related arguments for or against the SPA, and the nature of those arguments. We defined research-related arguments as arguments using evidence from studies about outcomes, such as mood disturbances or car crashes. All other arguments were defined as non-research-related (eg, enjoying a barbeque). Once arguments were coded within the two broad themes of research- related arguments and non-research-related, codes were administered to uncover the categories of arguments within research- and non- research-related arguments.
Each round of coding aimed to achieve a smaller set of overall codes until saturation was achieved. Coding proceeded in several iterative rounds. In the first round of coding, transcripts were read from start to finish without assigning codes. In the second round, codes were assigned in a manner that was purposefully descriptive in nature. In the subsequent rounds of coding, the code list was reviewed, then utterances re-coded with the aim of achieving a smaller list of overall codes. The final set of codes and quotes were reviewed and approved by all authors.
During the Senate session March 15, 2022, 4 senators spoke (1 Republican, 3 Democrat). There were 46 comments relating to arguments for or against pDST. Senator Markey (Democrat) made the most comments (37%), followed by Senator Murray (Democrat, 26%), Senator Rubio (Republican, 23%), and Senator Whitehouse (Democrat, 13%). Non-research-related arguments were pervasive (85%, Fig. 1); only 15% were research-related. All of the non-research-related arguments were in support of the SPA, with the most common emphasizing access to “sunshine” (21%) and the inconvenience of the clock change (21%), followed by arguments relating to evening activities (eg, little league games, 15%) and statements emphasizing widespread preference for later sunset (13%). All of the research-related arguments were against the SPA, with car crashes and heart attacks (25%) the most commonly mentioned followed by seasonal affective disorder (25%, Table 1). None mentioned other potential effects of pDST, such as safety, academic, economic, or energy usage outcomes. There was no discussion among senators or testimony by experts.
Policymakers often must make decisions with imperfect information, leading them to rely on a combination of rational arguments (eg, clear goals and sound sources) and irrational arguments (focused on emotions and feelings).16 The passing of the SPA is a clear example of the latter. Our analysis demonstrates that the arguments in the Senate SPA session emphasized non-research-related issues, such as access to sunshine ("So daylight saving time brings sunshine, smiles and savings to every place in the country – person in the country"). There was a paucity of research evidence that was cited during the Senate SPA session. The policymakers ignored a large body of evidence that demonstrates moving clock time for the entire United States one time zone eastward permanently would be hazardous to health, public safety, and learning, and be detrimental to multiple economic and energy usage outcomes.2–4,6,8,9 Since public health will be only one of multiple factors in policymakers’ decision-making, advocates should seek to support bipartisan policies that are aligned with optimal population health outcomes. It is critical that policymakers be informed about relevant scientific evidence when making decisions that affect the health of our nation and the scientific community must pursue all available channels to ensure that scientific evidence is considered in decisions that are translated into public policies.

Academic achievement in the first year of college is critical for setting students on a pathway toward long-term academic and life success, yet little is known about the factors that shape early college academic achievement. Given the important role sleep plays in learning and me…

Academic achievement in the first year of college is critical for setting students on a pathway toward long-term academic and life success, yet little is known about the factors that shape early college academic achievement. Given the important role sleep plays in learning and memory, here we extend this work to evaluate whether nightly sleep duration predicts change in end-of-semester grade point average (GPA). First-year college students from three independent universities provided sleep actigraphy for a month early in their winter/spring academic term across five studies. Findings showed that greater early-term total nightly sleep duration predicted higher end-of-term GPA, an effect that persisted even after controlling for previous-term GPA and daytime sleep. Specifically, every additional hour of average nightly sleep duration early in the semester was associated with an 0.07 increase in end-of-term GPA. Sensitivity analyses using sleep thresholds also indicated that sleeping less than 6 h each night was a period where sleep shifted from helpful to harmful for end-of-term GPA, relative to previous-term GPA. Notably, predictive relationships with GPA were specific to total nightly sleep duration, and not other markers of sleep, such as the midpoint of a student's nightly sleep window or bedtime timing variability. These findings across five studies establish nightly sleep duration as an important factor in academic success and highlight the potential value of testing early academic term total sleep time interventions during the formative first year of college.

Previous studies have linked exposure to light at night (LAN) with various health outcomes, but evidence is limited for the LAN-obesity association. Thestudy analysed data from 24,845 participants of the 33 Communities Chinese Health Study and obesity (BMI ≥28 kg/m(2)) was define…

Previous studies have linked exposure to light at night (LAN) with various health outcomes, but evidence is limited for the LAN-obesity association. Thestudy analysed data from 24,845 participants of the 33 Communities Chinese Health Study and obesity (BMI ≥28 kg/m(2)) was defined according to the Working Group on Obesity in China. The Global Radiance Calibrated Nighttime Lights data were used to estimate participants' LAN exposure. The mixed-effect regression models examined the LAN-BMI and LAN-obesity association. We found that higher LAN exposure was significantly associated with greater BMI and higher risk of obesity. Changes of BMI and the odds ratios (ORs) of obesity and 95% confidence intervals (CIs) for 2(nd), 3(rd), and 4(th) against the 1(st) quartile of LAN exposure were 0.363 (0.208, 0.519), 0.364 (0.211, 0.516) and 0.217 (0.051, 0.383); 1.228 (1.099, 1.371), 1.356 (1.196, 1.538) and 1.269 (1.124, 1.433), respectively. Age and regular exercise showed significant modification effects on the LAN-obesity association.