why you should shun that e-book at night

Use of a light-emitting electronic device such as e-books in the hours before bedtime can adversely impact sleep, overall health, alertness and the circadian clock, a new study has found as reported in The Times Of India.

Researchers at Brigham and Women's Hospital (BWH) compared the biological effects of reading a light-emitting electronic device (LEeBook) compared to a printed book.

"We found the body's natural circadian rhythms were interrupted by the short-wavelength enriched light, otherwise known as blue light, from these electronic devices," said Anne-Marie Chang, corresponding author, and associate neuroscientist in BWH's Division of Sleep and Circadian Disorders.

"Participants reading an LE-eBook took longer to fall asleep and had reduced evening sleepiness, reduced melatonin secretion, later timing of their circadian clock and reduced next-morning alertness than when reading a printed book," Chang said.

Previous research has shown that blue light suppresses melatonin, impacts the circadian clock and increases alertness, but little was known about the effects of this popular technology on sleep. The iPad readers had reduced secretion of melatonin.

The use of light emitting devices immediately before bedtime is a concern because of the extremely powerful effect that light has on the body's natural sleepwake pattern, and may thereby play a role in perpetuating sleep deficiency. Although iPads were used in this study, researchers also measured laptops, cell phones, LED monitors, and other eReaders, all emitting blue light.