Many people lie in bed texting and checking their social media accounts on their smartphone or tablet before going to sleep each night - but the habit could play havoc with a good night’s rest.
More than nine out of ten young people expose themselves to the blue light emitted from these devices, causing problems with sleep, a new survey has found.
The survey also showed that smartphone users regularly get no more than seven hours sleep a night, BBC Newsbeat reported.
Professor Richard Wiseman, who commissioned the YouGov poll described the findings as “extremely worrying”.
More than three-quarters (78 per cent) of the 2,149 adults questioned said they used electronic devices before going to bed.
This rose to 91 per cent among the 18 to 24-year-olds questioned in the survey.
The University of Hertfordshire academic told BBC Newsbeat: “The blue light from these devices suppresses the production of the sleep-inducing hormone melatonin, so it's important to avoid them before bed time.”
Adults are generally thought to require a minimum of seven to eight hours of sleep a night, while guidelines recommend about nine hours a night for teenagers.
The proportion of people thought to be getting too little sleep had risen by a fifth since a ”bedroom poll“ conducted last year by the National Sleep Foundation.
"This is a huge rise, and the results are extremely worrying because getting less than seven hours sleep a night is below the recommended guidelines, and is associated with a range of problems, including an increased risk of weight gain, heart attacks, diabetes and cancer," Professor Wiseman said.
In the survey, people were asked if they used a computer, tablet or smartphone during the two hours before they went to bed. They were also asked about their dreams – just one in ten agreed with the statement: “I would describe my dreams as pleasant.”
The findings come as a survey of 2,000 people suggested that under-25s check their phones 32 times a day.