There are many reasons you might feel tired, irritable, and headachy when you wake up in the morning – illness, allergies, noisy neighbors. But you might also blame it on too much light – especially blue light. Looking at your phone or TV before bedtime can mess with your natural sleep cycle.

Another source of trouble is outdoor lighting. Streetlamps, billboards, car headlights, and other sources fill the night with light. That creates a dome of light over most cities and towns – a dome of “sky glow.” In fact, 99 percent of all Americans live beneath such a dome.

The glow creates all kinds of problems. It prevents us from seeing the wonders of the universe. It can endanger wildlife. And many studies have shown that it can endanger our health as well.

That’s especially true with bluer light. Those wavelengths activate the receptors in the eye that we use most during the day. So they’re telling your body that it’s daytime, not night.

Exposure to bright outdoor lighting can suppress the body’s production of melatonin. That’s a hormone that plays an important role in the immune system, the health of several major organs, and the body’s natural rhythm. In particular, it can cause you to lose sleep, or to have a poor night’s sleep.

Experts recommend reducing the amount of outdoor light pollution, and making sure that streetlamps have a warmer glow – helping everyone to get a good night’s sleep.

More tomorrow.

Script by Damond Benningfield