Norway's Svalbard archipelago is the northern-most inhabited region of Europe. There, the sun never sets during the summer, producing a midnight sun.

It makes you wonder: "How do those folks sleep?"

That's because you know instinctively that if it's daylight out, your body thinks, "Hey, time to do stuff."

But in lower latitudes — like the U.S. — there's a midnight sun indoors.

Just think about all the lights that are on from 6 p.m. to 6 a.m. inside your home. Those lights are just as disruptive to your young children as the midnight sun is to, well, everyone.

For a new study, researchers from the University of Colorado Boulder created a dimly lit environment in 10 preschoolers' homes.

They then measured the children's levels of melatonin, a hormone that signals the body it's time to sleep, after the children spent the day in the darkened environment.

The next day the researchers exposed the kids to bright light for one hour before their bedtime and then returned them to the low-light environment.

That one hour's worth of bright light suppressed the kids' melatonin levels by up to 88 percent compared to all-low-light levels.

That shines a light on just how damaging illumination at night can be to your preschoolers' sleep cycle.

So dim children's bedroom lights an hour before they hit the hay; remove digital screens, and use dimmed booklights to illuminate pages as you read them to sleep.

Then do it yourself. Another study found that the same is true for adults: More light, less melatonin.