The Centers for Disease Control reports that nearly one-third of the American workforce is sleep-deprived and getting less than 6 hours of sleep a night (for most people 7-9 hours is best). The resulting drowsiness is responsible for fatal accidents and serious injuries, and chronic sleep deprivation has been linked to obesity, heart disease, diabetes, cancer, ADHD in adults, cognitive impairment, decreased immunity and premature aging.

If you’re finding it hard to get a good night’s sleep, it could be related to working late at your computer, bedtime reading on your Kindle, watching late-night TV, or making late-night calls on your smartphone. All these electronic devices have one thing in common: they emit blue light. And blue light is known to interfere with sleep.

Although blue light is the worst, light in general interferes with sleep. Our circadian rhythms are governed by light alternating with darkness. The neurotransmitter serotonin, secreted in response to light, keeps us awake and stimulated during the day, while melatonin, a hormone secreted in response to darkness, makes us sleepy. Light suppresses melatonin, and blue light suppresses it the most. Blue light is emitted by LED screens found in most computers, tablets (such as iPad and Kindle Fire), smartphones and many flatscreen TVs.

The more stimulating the activity and the brighter the screen on these devices, the more likely you’re going to have problems going to sleep and getting good quality sleep. Amber-tinted eyeglasses block blue light, but there’s no clinical evidence showing they lead to improved sleep.

What to do? According to the University of California at Berkeley Wellness Newsletter, simply turn off these devices an hour or more before bedtime. Although melatonin is available as a supplement it doesn’t help everyone, and it isn’t recommended for regular use.