October 23, 2025

expert reaction to study looking at light exposure at night and cardiovascular disease incidence

A study published in JAMA Network Open looks at night time light exposure and cardiovascular disease incidence. 

Prof Tim Chico, Professor of Cardiovascular Medicine and Honorary Consultant Cardiologist, University of Sheffield, said:

“This study shows the value of investing in large research initiatives like UK Biobank that support thousands of different researchers.

“The study finds people who are exposed to more light at night have a higher chance of developing certain types of serious heart disease.  Although night-time sleep exposure is “correlated” with future heart disease, this research can’t confirm whether light exposure causes the risk.  This is why statisticians often remind us that “correlation is not causation”.  There may be other differences in people exposed to light at night that are responsible for the greater risk of heart disease, although the researchers took several possible differences into account and still found that light exposure was a risk-factor.

“There are many risk factors for heart disease, but some, like ageing, are impossible to prevent.  This study may point to simple ways that could prevent heart disease, but there is no single ‘magic bullet’ for the epidemic of heart diseases facing the NHS.  To address this epidemic we also need to tackle smoking, air quality, diet, physical inactivity, obesity, high blood pressure and high cholesterol.”

‘Light Exposure at Night and Cardiovascular Disease Incidence’ by Daniel P. Windred et al. was published in JAMA Network Open at 16:00 UK time on Thursday 23 October 2025. 

DOI: 10.1001/jamanetworkopen.2025.39031

Declared interests

Prof Tim Chico: “No conflicts.”