Contemporary nonstop digital connectivity means that most of us are exposed to more blue light—the color of light emitted by our cell phones, computers, and other devices—than ever before in human history. Is this a problem?

Blue light is visible light with a relatively short wavelength of 400-450 nanometers. The shorter wavelength means that blue light, along with violet and indigo light, is of higher energy intensity than other lights on the visible spectrum. This is potentially a cause for concern because, at high enough doses, blue light is more likely to cause cell damage.

Although we have come to associate blue light with LED lights, it is actually everywhere. When light from the sun travels to Earth, the shorter, high-energy blue wavelengths collide with gas molecules in the atmosphere, causing blue light to scatter in all directions. This is what makes the sky look blue.

Our bodies use blue light from the sun to regulate our natural sleep and wake cycles. Blue light can also boost alertness, improve reaction times, elevate moods, and increase our sense of wellbeing. Before the advent of artificial lighting, humans were exposed to blue light during daylight hours, but then got a break at night. In modern times, however, we are often exposed to blue light at all hours from electronic devices such as cell phones and laptop computers, as well as energy-efficient fluorescent bulbs and LED lights. (Incandescent light, like sunlight, is broad spectrum, with lower concentrations of blue.)

While most researchers do not believe that blue light exposures from cell phones and computers are enough to damage the retina (despite the claims of blue light-protective eyeglass manufacturers), they are enough to disturb our sleep cycles. This is why we shouldn’t sleep with our cell phone near our bed. Even small bursts of blue light can disrupt the sleep cycle. Over time, this can have cumulative negative effects on our body’s rest, restore, and repair functions, which, over time, accelerate the effects of aging.

Getting enough sleep is as important for your body as a healthy diet, regular exercise, and effective stress management. We all know how haggard we look—and feel!—after a sleepless night. We’ve literally robbed our body of the time it needs to repair and restore our health at the cellular level. And, over time, lack of sleep is also linked to all kinds of health problems — from diabetes to hypertension to weight gain to lowered immune function.

So do yourself a favor and put your cell phone in a drawer or turn it off at night. And make it a habit to reduce your screen time as you approach bedtime. You’ll sleep better—and wake up better—for it!