Study links bedroom light exposure to changes in heart structure
Research finds that sleeping with as little as 3 lux of light may thicken the heart's left ventricle and impair its function, raising cardiovascular risk.
A recent study indicates that exposure to low levels of light while sleeping can alter heart muscle thickness and reduce pumping efficiency. Participants who slept in rooms with three lux or more – roughly the illumination of moonlight – showed thicker walls in the left ventricle compared with those who slept in near darkness. The condition, known as left-ventricular hypertrophy, is associated with higher chances of heart failure, arrhythmias and other cardiovascular problems.
"These changes are typically seen in response to chronic stress or injury to the heart," said Lu Qi of Tulane University, adding that the adaptation ultimately weakens the heart.
"It is time for clinicians, particularly those managing patients with heart failure or atrial fibrillation, to start asking about the sleep environment," said Thomas Münzel of University Medical Center Mainz. He recommended simple measures such as blackout curtains, warm-colored bedside lights, covering standby LEDs on electronics, or using a sleep mask.
The researchers suggest that light may disrupt circadian rhythms, which could explain the observed cardiac effects. Münzel also noted that reducing light pollution through shielded fixtures and dimmable or motion-activated streetlights is a feasible public-health strategy.