The debate over whether to keep daylight savings time has gained attention in recent years, with interest in understanding how the length of exposure to sunlight may affect health outcomes. In this study, we analyzed cancer incidence rates in counties located in different longitudinal positions within time zones and across time zone borders in the contiguous United States. Using both linear and spatial regression models, we found that differences in cancer rates are not significant within time zones or near time zone borders, which challenges previous research. Furthermore, we examined breast, liver, lung, and prostate cancer rates and found that only breast and liver cancers show an increase in incidence from the eastern border to the west within a time zone, while prostate cancer shows the opposite trend. Our study provides insights into the potential difference on human health incurred by an additional hour of sunlight in the morning versus in the evening, which could inform the ongoing discussions about daylight savings time.

翻译：关于是否保留夏令时的争议近年来备受关注，人们日益关注日光暴露时长对健康结果的影响。本研究分析了美国本土各时区不同经度位置及跨时区边界的县级癌症发病率。通过使用线性和空间回归模型，我们发现时区内部及边界附近的癌症发病率差异并不显著，这挑战了先前的研究结论。进一步分析乳腺癌、肝癌、肺癌和前列腺癌发病率后发现，仅乳腺癌和肝癌在时区东部边界至西部边界呈现上升趋势，而前列腺癌则呈现相反趋势。本研究揭示了早晨与傍晚额外一小时日照对人类健康的潜在差异影响，可为当前关于夏令时的讨论提供参考依据。