From the Mail Online in the UK,
Children who text and email late at night may be damaging their health. Teenagers and children who send electronic messages after they have been sent to bed may have poorer quality sleep and become moody, a study found. Those who were unable to put their phones or laptops to one side were also more likely to be anxious and depressed or suffer learning difficulties. The U.S. researchers said that unlike watching TV, which is a largely passive activity, sending emails and texts involved more interaction so kept the brain busy at the time when it should be shutting down. The pilot research team from the JFK Sleep Centre in Edison, New Jersey, gave questionnaires to 40 people aged between eight and 22, asking about their sleep habits and use of texts and emails.