For the last 50 years, the quality of sleep has been decreasing year after year. Recent studies performed by the University of Harvard clearly indicate that reading eBooks before sleeping causes health issues related to poor sleep at night. One can imagine why this might worry scientists because a lot of illnesses and terrible conditions, including most types of cancer have also been increasing for the same time so if there is any relation between being unable to rest at night and the possibility of getting such diseases, scientist must find it.
Scientists still haven't found the main cause for many of these undesirable conditions yet, so they are practically looking everywhere.
Without jumping to conclusions, reading eBooks before sleeping prevents sleeping and that alone may be linked to many other health issues. However, scientists have not been able to prove conclusively that an alteration in the sleeping process might cause a problem as serious as cancer, but they have certainly found some evidence that insomnia and poor sleep might be related to breast and prostate cancer (but more studies are needed to prove this conclusively).
Back to the main topic, scientists and researchers from Harvard University found out during an experiment that participants reading eBooks needed more time to fall asleep as opposed to those who read printed books.
The study showed that the first group: a) fell asleep after the second group, b) took longer the next day to reach alertness, reporting grogginess during the next day, c) their levels of melanin dropped, which is a sleep-inducing hormone that helps people fall asleep during the night and d) their REM cycle was drastically reduced in time, which means they actually had less hours of "effective sleep", that is, they did not have a good quality sleep like those who read printed books.
More studies are needed to understand what the long term effects of reading eBooks at night might be. Scientists are sure that reading eBooks for a long time will have negative effects, they just do not know how severe those negative effects can be.
