Blue light at night disrupts circadian rhythms and thus the natural sleep cycle.
Blue light (short wavelength) is a natural part of sunlight during the day, but exposure to it at night, for example from digital device screens or through indoor or night-time LED street lighting containing short wavelengths, can seriously disrupt circadian rhythms and thus sleep quality. Receptors in the retina of the eye (ganglion cells), which are sensitive to blue light, affect the biological clock by suppressing the production of melatonin, a hormone that readies the body for sleep. The brighter the light, the more melatonin production is reduced. Scientists at the Steven Lockley Laboratory at Brigham and Womenâs Hospital in Boston recommend night time use of red light, which minimally disrupts the biological clock and alertness.
Lack of sleep and its poor quality, caused by disruption of circadian rhythms, threatens human health.
The common lifestyle of todayâs society, including the frequent use of electronic devices before bedtime, significantly disrupts the natural alternation of light and dark that governs human biological rhythms. As a result, people are sleeping an average of two hours less than they did a century ago, not only affecting their ability to get a good nightâs sleep but also their overall well-being and health. Sleep plays a key role in strengthening memory, regulating the immune system and maintaining proper blood pressure. In addition, lack of sleep can lead to an increased risk of serious health problems including obesity, diabetes, heart disease and dementia. Research from New Yorkâs Rochester University has shown that quality sleep can reduce the risk of Alzheimerâs disease. At the same time, doctors agree that poor sleep in children is linked to the incidence of diabetes, obesity and learning disabilities.
