E-Readers Before Bed Kills Good Night's Sleep

Contrary to popular belief, e-reading before going to sleep harms the quality of sleep instead of helping one sleep at night.

Scientists at the Pennsylvania State University in University Park, Pennsylvania discovered that exposure to light during evening and early nighttime hours suppresses release of the sleep-facilitating hormone melatonin and shifts the circadian clock, making it harder to fall asleep at bedtime, reports American Live Wire.

Anne-Marie Chang, assistant professor of bio-behavioral health at Penn State, said in a statement reported by Wall Street Hedge, "Electronic devices emit light that is short-wavelength-enriched light. These lights have a higher concentration of blue light - with a peak around 450 nm - compared to natural light. They are completely different in composition from natural light and hence, can have a greater impact on sleep and circadian rhythms."

The team of researchers monitored the electronic devices usage pattern and sleep disorder of 12 adults for two weeks. They compared when the subjects used iPads as e-readers to when the same participants read from an actual print book prior to bedtime. The subjects' sleep, melatonin levels, alertness the following morning and other sleep-related factors were also analyzed.

Results showed that participants who used the e-readers before bedtime took 10 minutes longer to fall asleep while they were found falling into deep sleep in shorter periods of time when they didn't use any electronic device before bedtime.

"Our most surprising finding was that individuals using the e-reader would be more tired and take longer to become alert the next morning. This has real consequences for daytime functioning, and these effects might be worse in the real world as opposed to the controlled environment we used," said Chang.

The researchers also measured the amount of brightness coming from several devices including an iPad, iPhone, Kindle, Kindle Fire and Nook Color. The Kindle e-reader does not emit light, while the iPad, Kindle Fire and Nook Color emit similar amounts of light. However, the iPad is the brightest of the devices measured, according to DNA.

The study is published in the Proceedings of the National Academy of Science.