The dark night as a cardiovascular vital sign: personal light exposure, subclinical cardiac remodelling, and the urban exposome

“It is time for clinicians, particularly those managing patients with heart failure or atrial fibrillation, to start asking about the sleep environment: how dark the bedroom is, whether the patient works night shifts, and how much screen use occurs after sunset. The advice is simple and inexpensive: blackout curtains, warm-coloured bedside lighting, and covering the small standby LEDs on household electronics. From a public health perspective, the implications are larger still. Light pollution is one of the few environmental hazards that cities can control directly and affordably. Shielded fixtures, warm-spectrum bulbs, and dimming or motion-activated streetlights are already available, energy-efficient, and climate-friendly.”

Lu QiProfessor of epidemiology, Tulane University

“This is the first study of its kind, and it shows that exposure to higher levels of light at nighttime is linked to cardiac remodelling. This is where the structure and function of the heart changes and we typically see it in response to chronic stress or injury to the heart. It's our body's way of adapting to that stress, but ultimately it weakens the heart and can lead to heart failure.”

“Nothing here changes a prescription.”