SerpApi.Org
For the first time, Northwestern Medicine scientists have detailed how fall and spring daylight saving time transitions affect a person's risk of developing retinal vascular disease. The study is published in Scientific Reports.
Subscribe to our newsletter for the latest sci-tech news updates.
The nationwide cohort analysis, led by Rukhsana Mirza, MD, the Ryan-Pusateri Professor of Ophthalmology and vice chair of Faculty Affairs in the Department of Ophthalmology, found that patients had up to a 30% higher risk of developing retinal vascular disease in the month following the transition to daylight saving time in the spring and a 20% lower risk of disease in the month following the transition to daylight saving time in the fall.
"Our study suggests gaining an hour of sleep may be protective against disease risk," said Mirza, who is also a professor of medical education. "Even one hour of change can affect a patient's health, and perhaps patients who are reporting new symptoms after a time change, specifically in the spring, may warrant closer evaluation."
The retina's link to body clocks
Transitions to daylight saving time have been shown to cause disruptions in circadian rhythm, the body's 24-hour internal clock that regulates the sleep-wake cycle, hormone production and body temperature, among other essential bodily functions.
The retina—the innermost, light-sensitive layer of tissue in the eye—provides a "window to the body" and plays an important role in circadian rhythm, Mirza said.
Recent studies have shown an association between transitions to daylight saving time, which can result in disrupted sleep, and an increased risk of acute cardiovascular events, including ischemic stroke.
"We have seen how daylight saving time transitions, particularly the spring transition when we lose an hour of sleep, are associated with increased rates of heart attack and stroke. This led us to ask whether similar effects would occur in the retina, which is one of the most metabolically active tissues in the body and contains some of the body's most complex microvascular networks," Mirza said.
How the team measured risk
To better understand how circadian disruption affects retinal vascular health, Mirza's team performed a retrospective analysis of health insurance claims data from more than 18 million patients ages 18–64 who were newly diagnosed with retinal vascular disease. Patients were enrolled in the Merative MarketScan Commercial Database between 2012 and 2014.
The incidence of newly diagnosed retinal artery occlusion (RAO), retinal vein occlusion (RVO), proliferative diabetic retinopathy (PDR) and neovascular age-related macular degeneration (nvAMD) was determined after the fall daylight saving time transition, spring daylight saving time transition and a summer (July) or winter (January) control period.
Survival analysis was then used to determine the effect of variables of interest on new-onset retinal vascular disease during one-week and one-month periods following the daylight saving time transition.
Spring and fall moved differently
From their analysis, the investigators found that, with a summer control period, there was a roughly 20% lower risk of RVO and PDR in the month following the fall daylight saving time transition.
However, there was a nearly 30% increased risk of a new diagnosis of PDR and nvAMD in the month following the spring daylight saving time transition.
"I think that relationship was pretty interesting, and it makes a lot of sense. Studies have shown that losing an hour of sleep and circadian misalignment can cause inflammatory responses and metabolic derangements, and there's also been some literature suggesting that getting an hour of sleep in the context of daylight saving might be protective," said Kyle Chan, '23 MD, a resident physician in the Department of Ophthalmology and co-first author of the study.
Replication is the next test
Chan also noted limitations of the study, including access to only three years of patient data, but said he hopes future work will replicate the findings using other, larger databases.
"In the future, we'd love to see if other groups can replicate our findings in non-overlapping databases, for example those in the academic setting, or look at more years of data as well to see if these findings hold true," Chan said.
The investigators also hope the findings will prompt future studies to investigate the impact of daylight saving time transitions and sleep disturbances on a more patient-level basis.
"I think this really opens up new opportunities for collaboration among ophthalmology, neurology, sleep medicine and cardiovascular medicine—really exciting possibilities to understand the whole person," Mirza said.
More information: Kyle S. Chan et al, Daylight saving time transition and new-onset retinal vascular disease: a nationwide cohort study, Scientific Reports (2026). DOI: 10.1038/s41598-026-55281-7
Provided by Northwestern University
This story was originally published on Medical Xpress.
