Credit: health.harvard.edu
Blue light — one of the seven colors in a rainbow’s visible spectrum — is produced by the sun. We need daylight’s natural blue rays for at least 20 minutes every day to enhance our alertness, support our mood and regulate our circadian rhythm. But studies have shown that nighttime exposure to artificial blue light emitted from smartphones, computer monitors, tablets and laptops can lead to serious health problems.
At least 80% of American adults use the internet every day — four in 10 report being online constantly. The average daily screen time is a stunning 7 hours and 3 minutes. Even seniors rack up over five hours every day and nearly 60% of users scroll on a device an hour or less before bedtime.
After sundown, the brain releases the sleep hormone melatonin to promote drowsiness. Evening exposure to electronic blue light suppresses melatonin production and interrupts our circadian rhythm. Our bodies compensate by secreting stress hormones like cortisol, and depleting mood stabilizers like serotonin. As a consequence, we don’t sleep as long or as deeply. Worse, studies have linked long-term blue light exposure to an increased risk of depression, obesity, type 2 diabetes, heart disease and even cancer.
Credit: wikihow.com
The best way to avoid these health risks is to stop using your digital devices at least two hours before bedtime. After sunset, turn down the brightness of your screen and switch to an evening setting, like Night Mode for PCs or Night Shift for Macs. Computer applications that filter out your device’s blue light can help. Experts recommend limiting computer and phone use outside work to a daily total of two hours, which may sound hard to do. Start with a modest goal, like shutting off your device 30 minutes early, and go from there.
For those who can’t or won’t reduce nighttime screen use, wearing blue light-blocking glasses may help, but the most effective brands can be somewhat costly. Eyewear with orange-tinted lenses block blue light and other colors too, making it difficult to see at night: They are not recommended.
Blue light-blocking glasses do not prevent eye strain. Blue light has not been shown to damage the eye, but eye strain from excessive screen time is common. We blink half as often when staring at our digital devices — only seven times a minute — making eyes dry and irritated. Try the 20-20-20 rule: Every 20 minutes, look at an object 20 feet away for at least 20 seconds.
Dr. Mary Jenkins, a contributor to the Herald and member of its board of directors, retired after nearly 40 years as a family practice physician in New York state.