Q&A: Why Is Blue Light before Bedtime Bad for Sleep?

In the modern age of technology it is not uncommon to come home after a long day at work or school and blow off steam by reading an e-book or watching television. Lately, however, scientists have been cautioning against using light-emitting devices before bed. Why? The light from our devices is “short-wavelength-enriched,” meaning it has a higher concentration of blue light than natural light—and blue light affects levels of the sleep-inducing hormone melatonin more than any other wavelength.Changes in sleep patterns can in turn shift the body’s natural clock, known as its circadian rhythm. Recent studies have shown that shifts in this clock can have devastating health effects because it controls not only our wakefulness but also individual clocks that dictate function in the body’s organs. In other words, stressors that affect our circadian clocks, such as blue-light exposure, can have much more serious consequences than originally thought.To discuss the growing concern Scientific American MIND consulted with Thomas Jefferson University neuroscientist George Brainard, who was among the first researchers to investigate how different wavelengths of light affect the release of melatonin, and Harvard University neuroscientist Anne-Marie Chang, who recently discovered that the effects of light-emitting devices on circadian systems extend beyond evening and into the following morning......READ MORE