What harm can occur if you sleep with the lights on

A recent study has indicated this

Looking at light for prolonged periods at night disrupts the body’s circadian rhythm, the internal “clock” that regulates sleep and wake cycles. This puts continuous stress on the heart because the brain interprets light exposure at night as daytime. As a result, falling asleep is delayed. For better sleep, researchers recommend keeping bedrooms dark at night. Doctors also suggest using thick curtains on windows to prevent outside light from entering.
 

People who are exposed to high levels of light at night may develop various heart problems. According to the study, the risk of heart failure increases by 45–56%, and irregular heartbeats rise by 28–32%. The researchers did not provide information about the sources of light but focused on the intensity of the light.
 

Daniel Windred, one of the researchers, said that this is the first large-scale study showing that nighttime light exposure can be a major and powerful risk factor for heart disease.
 

The study was recently published in the JAMA Network Open journal. A team of researchers from Flinders University, Australia, conducted the study on the presence of light before sleep. They collected and analyzed data from nearly 89,000 patients in England, tracking their heart health over 10 years. Light exposure data was collected using a special smart tracker.