Light in the bedroom at night may harm heart health, experts warn

Leaving a light on in the bedroom overnight may affect health more seriously than it appears at first glance. A study suggests that even a small amount of light exposure at night could be linked to a higher risk of heart problems.

Why light is a concern

Researchers found that light brighter than roughly 3 lux — about the intensity of moonlight — is associated with a greater risk of heart failure, atrial fibrillation, heart attack, stroke, and death from cardiovascular disease.

The explanation lies in the body's circadian rhythm. Light affects the production of melatonin, the hormone responsible for regulating sleep. When too much light reaches the eyes in the evening or at night, melatonin levels can drop, which in turn worsens sleep quality.

Blue light is especially harmful

Experts point out that blue light, emitted by smartphone, computer, and television screens, is the most problematic. Warm, dim light in orange or red tones, on the other hand, has a much smaller effect on sleep.

What experts recommend

Sleep specialists recommend several practical steps: dimming lights one to two hours before bedtime, avoiding smartphone and computer use for at least an hour before sleep, and using thick curtains or blinds to keep street lighting from entering the room.

Following these recommendations is especially important for people who suffer from insomnia or other chronic sleep disorders, since night-time light exposure can further disrupt their already impaired circadian rhythm.