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  • Researchers examined the relationship between spatially derived environmental exposures—including artificial light at night, noise, greenspace, and air pollution—and participant sleep outcomes. Among California Teachers Study participants, each of these exposures appeared to be associated with sleep. Artificial light at night and air pollution were associated with shorter sleep duration; noise was associated with longer sleep latency (the amount of time it takes to fall asleep); and greenspace was associated with increased sleep duration and decreased sleep latency.  Read more here.

  • Researchers found that compared to average sleepers (7-9 hrs/night), long sleepers (10+ hrs/night) had an increased risk of estrogen-mediated cancers. Read more here.

  • Chronotype refers to an individual's circadian typology, meaning one's natural inclination for the time of day they prefer to sleep. This study examined the association between endometrial cancer risk and chronotype within the California Teachers Study.  Researchers found that compared to morning types, women who were definite evening types had a statistically significantly elevated risk of endometrial cancer (OR=1.44). The association between evening type and risk of endometrial cancer was stronger among obese women than among non-obese women.  Read more here.

  • This 2023 study investigated whether self-reported measures of sleep were associated with risk of breast cancer among postmenopausal California Teachers Study participants. The team looked at sleep quality, latency, duration, disturbance, sleep medication use, and chronotype (meaning preference for morning or evening activity). In this study, measures of sleep quality were not associated with risk of breast cancer. However, participants with a preference for evening activity did have a slightly elevated risk of breast cancer. Read more here.

  • This 2020 study evaluated the risk of breast cancer associated with sleep deficiency among postmenopausal women in the California Teachers Study. Using CTS questionnaire data to ascertain several components of sleep deficiency, including quality, latency, duration, disturbance and use of sleep medications, researchers found that sleep deficiency may be a risk factor for breast cancer. Read more here.

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