The “secret” to alert, energetic days and restful nights is not just morning light; we also need darkness at night. Even low levels of light before (or during) sleep will delay and reduce the melatonin rise that tells our bodies it’s bedtime. (Of course, too much darkness can also be a problem, resulting in city’s putting mirrors on top of mountains – more on that in a separate blog post.)

Dark nights began to disappear from the world when we started to electrify it. But a real knockout punch came from the glow of our screens. Our computers, tablets, and smartphones all deliver a dose of blue light that’s just about the perfect wavelength to stimulate the receptors in our eyes that tell us it’s time to wake up. And most of us can’t keep away from those essential machines during the hours before we head to bed.

Here’s a solution that we often recommend to our patients: a program/app called f.lux (and others like it) will adjust the color of your screen to the time of day, reducing the blue glow as you get ready for sleep. Not great if you’re a graphic artist on a deadline but a pretty good fix for the rest of us.