Lighten Up: Indoor lighting and health

It’s a few minutes before five on this January evening as I start writing this post, and the sun has just slipped behind Mount Shavano, one of the “fourteeners”–peaks taller than 14,000 foot elevation–that form the western wall of our valley. As I watch the natural light outside fade, I’m thinking about turning on the lights inside.

I haven’t lept up to hit the switch though for two reasons: One, the light outside is still really lovely, as the sun’s last rays lay golden and pink stripes on the high peaks. If I turn on the lights too soon, I might miss the few moments of really spectacular color that sometimes paint the sky after the sun sets.

Like the photo below, which I shot last night when I happened to look up at just the right moment. I grabbed my camera, rushed out the kitchen door, hopped up on the sitting-height raised beds in the kitchen garden, and snapped a couple of shots before the colors ebbed and the sky went dark.

(The building in the foreground of the photo with the downward-aiming lighting is Ploughboy, the local food grocery store in our ‘hood. It was cited in a Budget Travel story naming Salida as one of the 20 “coolest” small towns in the country, in part for our local food scene. What a hoot!)

Reason two for not turning on the lights too quickly is in this Science News story reporting on new research on indoor lighting and its effects on our health. It’s not good news. Earlier research showed a strong statistical correlation between people who work at night–indoors or under bright lights–and certain cancers, including breast cancer.

The new study extends that and may explain why: Spending evening and nighttime hours exposed to bright indoor lighting reduces production of melatonin, the hormone that sets your biological clock–and plays a role in  preventing certain cancers, as well as depression, cardiovascular disease, strokes, and type 2 diabetes. (Clearly, we’re sensitive to preventing cancer in our household with Richard’s brain cancer, but this isn’t just about cancer: the connection between melatonin levels and health applies to us all.)

Exposure to bright indoor lighting didn’t just reduce melatonin production a little. Study subjects who spent the evening in a room with light levels at 200 lux, about the light level in the average living room, produced an average of 71 percent less melatonin, and started producing it very late, less than half an hour before scheduled lights-out time. Which meant they were less likely to sleep deeply, since melatonin is involved in regulating sleep as well. Poor sleep in turn affects all sorts of other health issues, from weight gain to heart disease.

Those who stayed up all night in bright lighting fared just as badly to much worse: their melatonin production averaged less than half of normal, with some subjects producing barely any, at 92 percent less than normal.

Does this mean we should all sit in the dark, our evenings lit only by the glow of our big-screen TVs, computers, or by candlelight for those romantics among us? Not necessarily. But it does mean we might want to turn down the indoor lighting. What’s healthy for us is also healthier for the planet, saving electricity and money in the bargain.


It’s almost seven o’clock now. (Yes, it takes me two hours to write an average blog post–I’m not quick.) It’s dark out, and Richard and I are sitting side by side in the living room, laptops in our laps. Yup, we have the light on–that’s light, singular, one overhead ceiling fan light, not the two we’d normally use. One provides plenty of light, and the softer lighting is restful on the eyes.

Maybe tomorrow night we’ll try candlelight…

Blessings to you all, and good night!