The survey also showed that as many as 28 million people in the UK have a duration of not sleeping more than seven hours a day .
Professor Richard Wiseman , who conducted the study , said the findings " quite alarming . "
Of the 2,149 adults surveyed , 78 percent said they check their phone or tablet before bed .
This figure increased in the age group 18 to 24 years , 91 percent of them admitted to turning on the phone in the room at night .
" Blue light suppresses the production of these devices hormone melatonin which induces sleep , so it's important to avoid its use before bedtime , " said Professor Richard Wiseman , from the University of Hertfordshire .
Each person takes a different bed , but adults are generally considered to require a minimum of seven to eight hours each night . (see also: pakan burung kacer)
Adolescents recommended to sleep longer, about nine hours . " The results of ( survey ) is very worrying because less than seven hours of sleep is not recommended , and it can relate to a variety of problems , including an increased risk of weight gain , heart attack , diabetes and cancer , " said Prof . Wiseman .
Last week ophthalmologist said that too often using smart phones can increase the risk of eye damage .