E-books affect sleeping patterns

Higher blue light portion throttles release of the sleep hormone melatonin

23/12/2014

Reading brightly lit tablets can have a negative impact on sleep. According to a study, "four hours of reading time can result in a 1.5-hour shift in the sleep-wake cycle". This reports the journal Proceedings of the US Academy of Sciences (PNAS) in its latest issue. The trigger is "the high proportion of blue light suspected".

Comparison test with conventional books
"The use of electronic reading, communication and entertainment devices has increased dramatically in recent years," said researchers around Anne-Marie Chang of Harvard Medical School in Boston. Therefore, they would have wanted to see how this trend affects sleep. To investigate this, twelve tabloid women and men spent five days reading and reading tablets and books in controlled conditions under controlled conditions before comparing the results.

Melatonin secretion shifts
The measurements showed that the subjects who read tablets fell on average about 10 minutes later, that the REM phases were shortened by twelve minutes and that the subjects in the morning were not as fit as the subjects of the control group.

The most pronounced effects were the melatonin level, which fell by 55 percent. As a result, the sleep-wake rhythm in the tablet group shifted backwards by about 1.5 hours compared to the group with conventional reading. They were at 10:00 clock much wetter than the bedtime „bookworms“.

Blue light suspected as the cause
To explain the causes, the researchers referred to Chang on older studies, which blame high levels of blue light such as television equipment, computer monitors and tablets and Tablets also account for it.

However, the impact of e-books has not been separately explored in the study. As the Washington Post said, manufacturers of such e-books, such as Kindle or Amazon, have been using other light sources for their products, which would make them much more eye-friendly.

Increased cancer risk
Regarding the effects on health, Chang's researchers said that the study was particularly important, „because it raises the risk of colorectal cancer, prostate cancer and breast cancer that has already been identified in studies on shiftwork and recognized by the WHO as a carcinogen, due to exposure to melatonin at night exposure;“... confirm. "Our results show that the electrical light we experience between sunset and bedtime has profound biological effects," the researchers write. However, they limited the results of their study to suggest that the tablets were maximally lit while the light in book reading was heavily insulated. (Jp)