Night light and light from the corridor can harm the heart – what scientists have found

A study published in the European Heart Journal has shown that even weak night light (above 3 lux) during sleep is linked to changes in heart function. Participants with higher light exposure had thickening of the left ventricle and a 29% higher risk of heart failure. Cardiologists recommend minimizing unnecessary lighting in the bedroom.

A study published in the European Heart Journal has identified a link between nighttime lighting and heart health. Scientists analyzed data from over 11,000 UK residents who wore sensors for a week to record light levels during sleep. Three years later, MRI scans showed that participants exposed to light above 3 lux (e.g., from a phone screen or light from the corridor) had thickening of the left ventricle and signs of impaired heart stretching during contraction. During follow-up (8-10 years), this group had a 29% higher risk of heart failure. Cardiologist Chen-Han Chen noted that night light can disrupt circadian rhythms and sleep quality. Experts recommend minimizing unnecessary light sources in the bedroom but do not call for complete darkness.