E-books have become increasingly popular over the past few years.
They have backlit screens, which make them ideal for reading before bed in a dark room. However, this could negatively affect sleep.
One study gave young adults a printed book and an e-book to read before bed. The researchers found that when using the e-book, the participants took longer to fall asleep.
They were also more alert during the evenings and less alert in the morning compared with when they read the printed book. Such results suggest that e-books could have a negative impact on sleep.