Daylight Saving Time Impacts Risk of Retinal Vascular Disease

For the first time, Northwestern Medicine scientists have detailed how autumn and spring daylight savings time transitions impact a person’s risk of developing retinal vascular disease, according to a recent study published in Scientific Reports.

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 patients had an up to 30 percent higher risk of developing retinal vascular disease in the month following the transition to daylight savings time in the spring, and a 20 percent lower risk of disease in the month following the transition to daylight savings time in autumn.

“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 impact a patient’s health and perhaps patients who are reporting new symptoms in the period after a change in time, specifically in the spring, may warrant closer evaluation.”

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, to increased risk of acute cardiovascular events, including ischemic stroke.

“We have seen how daylight savings 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 if these similar effects would be happening 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.

To better understand how circadian disruption impacts retinal vascular health, Mirza’s team performed a retrospective analysis of health insurance claims data from more than 18 million patients aged 18 to 64 years 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 autumn 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 daylight saving time transition.

From their analysis, the investigators found that with a summer control period, there was a roughly 20 percent lower risk of RVO and PDR in the month following the autumn daylight saving time transition.

However, there was a nearly 30 percent increased risk of 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. There’s been literature showing that losing an hour’s sleep and circadian misalignment can cause inflammatory responses and metabolic derangements, and there’s also been some literature suggesting that getting an hour’s sleep in the context of daylight savings might be protective,” said Kyle Chan, ‘23 MD, a resident physician in the Department of Ophthalmology and co-first author of the study.

Chan also noted limitations of their study include having access to only three years’ worth of patient data but that he hopes future work will replicate their 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 savings transitions and sleep disturbances on a more patient level.

“I think this really opens up new opportunities for collaboration between ophthalmology, neurology, sleep medicine, cardiovascular medicine… really exciting possibilities to understand the whole person,” Mirza said.

Brian Cheng, ‘22 MD, a former medical student and a vitreoretinal surgery fellow at John Hopkins University, was co-first author of the study.

Co-authors of the study include Margaret Banker, PhD, assistant professor of Preventive Medicine in the Division of Biostatistics and Informatics, and Phyllis Zee, MD, PhD, ‘87 GME, the Benjamin and Virginia T. Boshes Professor of Neurology and director of the Center for Circadian and Sleep Medicine.

This study was supported by an unrestricted departmental grant from Research to Prevent Blindness and Merative MarketScan Dissertation Support Program by access to the MarketScan research database.