Passage IV

Circadian Rhythm and Blues

People who have trouble falling asleep might potentially have the chance to benefit from a simple suggestion:turn off the light, especially if it's blue. Though scientists have long known that light levels influence our ability to fall asleep, recent studies suggest that certain kinds of light effect the body more than others. Light composed of blue wavelengths, which computers, televisions, and cellular phones emit, is especially effective at causing wakefulness.

The problem with blue light is a subject researchers have recently begun to study. One function is, vision—the eye receives the input necessary for sight. Additionally, the eye helps regulate the body, using sensors in the retina that detect variations in daylight. Based on the amount of light the retinas sense, the body sets its internal clock to a twenty-four-hour cycle called the circadian rhythm, which cues body functions, such as digestion and blood pressure.

Crucial to the functioning of the circadian rhythm is melatonin, a light-sensitive hormone secreted by the brain. Melatonin promotes sleep. When the retina detects bright light, the body suppresses melatonin to encourage wakefulness. Still, melatonin production increases when light levels drop, inducing drowsiness. Blue wavelengths of light are particularly adept at slowing melatonin release.

The widespread use of technology is another reason that blue light is problematic. For example, blue light-emitting diodes are replacing lightbulbs that emit other wavelengths of light. Also, many people are using high-tech devices these days. All its extra blue light can disrupt the circadian rhythm of technophiles.

Aware of the blue light problem, some technology designers are working to better control circadian rhythms. Hoping to invent lights and screens that can emit different wavelengths of light depending on the hour of the day. Meanwhile, experts suggest turning off technological devices an hour before bed to promote melatonin release and a healthy circadian rhythm. Melatonin is important to circadian rhythms.